compiling teaching content of automotive electrical and electronic system

MINISTRY OF EDUCATION AND TRAINING HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION GRADUATION THESIS AUTOMOTIVE ENGINEERING TECHNOLOGY Ho Chi Minh City, May 2024COMPILING TEACHI

INTRODUCTION

Reasons for choosing the topic

Because the old curriculum has not been updated for a long time and lacks visual figure for students and the evolution of vehicle electrical systems, including batteries, starting and charging systems, immobilizers, and anti-theft mechanisms, has been well- documented in automotive research This literature review provides a concise overview of these systems, highlighting key studies and advancements that inform the development of comprehensive lecture materials for university students.

Topic’s ojective

- Compiling Practical Teaching Content Of Automotive Electrical and Electronic systems

- Repair for all training models

- Build practice sheets for all models

- Build the review question for after class

Object and study range

- Structure and function of the automotive electrical and electronic system

- Circuit diagram of automotive electrical systems

- Operating principle of automotive electrical systems

- Field: Basic Automotive Electrical systems (Electrical and electronic device, Starting system, Charging system, Immobilizer system, Anti-theft alarm)

Research method

Base on the existing theories, analysizing additional research from books, and reference materials from automotive manufacturers.

Literature review

Teaching electrical concepts, particularly in automotive contexts, necessitates a comprehensive approach that encompasses both theoretical foundations and practical applications In compiling teaching content for electrical systems, educators draw from

2 a diverse body of literature encompassing various disciplines such as electrical engineering, automotive technology, and pedagogy This literature review aims to explore key considerations and best practices in compiling electrical teaching content, focusing on the automotive domain

THEORETICAL BASIS

The electrical devices are used in many systems of the car and have different functions

Heat is generated when electricity passes through conductors, the greater the current, the greater the heat generation capacity of electricity Part of the loss in the transmission process is in the heat dissipation process

Figure 2.2 Cigarate lighter on vehicle

Light is emitted when electricity passes through certain types of special conductors like filament wires It heats up these conductor types to the temperature of illumination

Electrical and electronic device used in automobiles

Overview about electricity

The electrical devices are used in many systems of the car and have different functions

Heat is generated when electricity passes through conductors, the greater the current, the greater the heat generation capacity of electricity Part of the loss in the transmission process is in the heat dissipation process

Figure 2.2 Cigarate lighter on vehicle

Light is emitted when electricity passes through certain types of special conductors like filament wires It heats up these conductor types to the temperature of illumination

A magnetic force is created when electricity passes through a conductor or coil of wire, with the strength of the magnetic field increasing with the number of turns of wire, such as in ignition coils, generators, and fuel injectors Every substance consists of atoms, which include a nucleus and electrons A metallic atom has free electrons These free electrons are electrons that can move freely from atom to atom The transmission of these free electrons within metallic atoms creates electricity Therefore, electricity running through an electric circuit is the movement of electrons within a conductor When a voltage is applied across both ends of a metallic conductor, electrons flow from the negative terminal to the positive terminal The direction of electron flow is opposite to the direction of the current flow

Electricity is the directed movement of free electrons within a conductor

Electricity consists of three fundamental elements:

Current intensity (I): It represents the strength of the current The greater the current intensity, the larger the amount of charge passing through the conductor per unit time Unit: A (Ampere)

Figure 2.5 Xenon headlight Figure 2.4 Filament bulb Figure 2.3 LED

Voltage measures the electrical force driving current flow in a circuit Its magnitude directly affects the current's strength, such that higher voltage corresponds to a greater current The unit of measurement for voltage is the Volt (V).

This is the quantity that expresses the resistance to the flow of current in a circuit Unit: Ω (Ohm)

The relationship between current, voltage, and resistance can be expressed by Ohm's Law

Electrical power is expressed by the amount of work done by an electrical device in one second

Power is measured in Watts (W), and 1W is the amount of work received when a voltage of 1V is applied to a load, resulting in a current of 1A flowing through it in one second

Power is calculated by the following formula:

If 5A of current is applied for one second with a voltage of 12V, then the electrical device accomplishes a power of 60W (5 x 12 = 60).

Direct Current and Alternating Current

A current with a constant direction and a constant amplitude is called direct current (DC) On the other hand, a current that changes direction and has a varying amplitude is called alternating current (AC)

This is a type of current with a constant direction, from positive to negative poles, such as in car batteries or dry cells

Alternating current (AC) is an electrical current that periodically reverses its direction It is commonly used in household power outlets and industrial applications AC generators produce alternating voltage, which is often used to power electrical devices.

Figure 2.7 Direct current and alteranating current

Electronic components

There are various types of resistors used in automobiles One commonly used resistor in both electronic engineering and automotive applications is the carbon resistor Carbon resistors consist of a mixture of carbon powder and other substances blended in different proportions, resulting in different resistance values The resistor is coated with an insulating layer on the outside The resistance value of the resistor is indicated by colored bands

The appearance of a carbon resistor and the colored bands is shown in Figure 2.9

In some cases where it is necessary to maintain a high current, power resistors are used These resistors allow operation at high power because a metal plate is added to the body to dissipate heat for the resistor

In special cases, if there is no fourth band (for 3-band resistors), the tolerance is 20% Reading method:

Read from left to right The first and second bands represent the actual value of the resistor, the third band represents the multiplier (10^x, where x is the value corresponding to the color), and the fourth band is the tolerance of the resistor

If the resistor bands are red - violet - orange - silver from left to right, then the value of the resistor will be:

Resistor production does not involve creating components with every conceivable resistance value Instead, manufacturers adhere to standardized values, denoted by the first and second color bands on the resistor This standardization simplifies the manufacturing process and ensures consistency in resistor performance.

Conventional table of color bands of resistors:

Figure 2.9 Conventional table of color bands of resitors

For resistors with 5 color bands, the reading method is similar to that of resistors with

4 color bands, except that the first 3 color bands represent 3 digits, the 4th band represents the multiplier, and the 5th band represents the tolerance

A type of resistor whose resistance value changes with temperature Thermistors are commonly used to protect power amplifiers or serve as sensors in temperature- controlled automatic control systems

9 There are two kind of thermistor:

A negative temperature coefficient thermistor is a type of thermistor where the resistance decreases as the temperature increases, and decrease when the temperature increase

A positive temperature coefficient thermistor is a type of thermistor where the resistance increases as the temperature increases, increase when the temperature decrease

A negative temperature coefficient thermistor is a type of semiconductor with a resistance that varies with changes in temperature In other words, a thermistor can determine temperature by sensing resistance

In automobiles, thermistors are used in coolant temperature sensors and intake air temperature sensors, etc

A piezoelectric element will generate a voltage when subjected to pressure causing it to deform (usually quartz) or will deform if subjected to voltage It operates as a device that converts electrical energy into mechanical energy

It is commonly used for pressure sensors or for knock sensors mounted on the engine block

Figure 2.10 Thermistor symbol and value

Magnetic resistance element will change when the direction of the magnetic field applied to it changes

Because the changes in resistance in these elements are small, they are amplified by ICs (integrated circuits) Then this resistance is converted into pulses or analog signals to use them as vehicle speed sensor signals

A capacitor comprises electrodes, typically consisting of metal plates or foils, positioned opposite each other Separating these electrodes is a dielectric material, acting as an electrical insulator This material can vary in composition and can include air, as seen in the provided diagram, where air serves as the dielectric medium.

When applying voltage to both electrodes by connecting the positive and negative terminals of a battery, the electrodes will accumulate positive and negative charges

11 When the electrodes of a capacitor with stored charge are short-circuited, there will be an immediate current flowing from the positive terminal (+) to the negative terminal (-) neutralizing the capacitor Thus, this capacitor discharges Besides the charge storing function described above, a significant characteristic of a capacitor is that it blocks the flow of direct current Some electrical circuits utilizing the charge-storing function of capacitors include: voltage regulation circuits, backup power for microprocessors, timing circuits for charging and discharging capacitors, circuits using capacitors to block direct current, filters to extract or eliminate specific frequency components By utilizing these characteristics, capacitors are used in automotive electrical circuits for various purposes, such as noise suppression or replacement for power sources or switches

When a direct current voltage is applied to a fully discharged capacitor, the current will start flowing at a fast rate As the capacitor begins to charge, the current will decrease Eventually, when the static capacitance (charge-storing capacity of the capacitor) is reached, the current will stop flowing The voltage across the capacitor at this point equals the applied voltage

There are 2 types of capacitors classified by their properties:

Polarized capacitors: Capacitors with clear positive (+) and negative (-) polarities, thus cannot be reversed

Non-polarized capacitors: Capacitors without distinct polarities, can be connected in either direction in the circuit

There are 2 most commonly used effects:

When an alternating current flows through a capacitor, it will not be blocked like direct current because the capacitor does not react to low frequencies However, at high frequencies, the capacitor will have the ability to block the current Therefore, capacitors can be used as a filter, removing unwanted high-frequency components and passing through desired frequency signals

The voltage stabilizing effect of a capacitor is to keep the voltage across a circuit stable and not subject to sudden changes When a circuit receives a large voltage peak or rapid oscillations, the capacitor can absorb some of this energy and supply it back to the circuit when needed This helps reduce unwanted voltage fluctuations and protects the devices in the circuit from damage

Figure 2.14 Charge and discharge graph of capacitor

A switch is a device for making or breaking the connection in an electric circuit It can be manually operated by a person or can be automatically controlled

• Push-button switch, toggle switch

Figure 2.16 Push-button swich diagram

• Lever switch, temperature detection switch

A lever switch is used for combination control levers in vehicle lights, windshield wiper switches It is constructed like a multi-contact switch

A temperature switch utilizes a thermal sensor to detect temperature, and if the temperature reaches a certain level, the switch will automatically disconnect

Figure 2.18 Level switch on combination switch control

• Current sensing switch, oil level sensing switch

A current sensing switch is a safety device used in electrical systems to detect and interrupt leakage currents outside the circuit

An oil level sensing switch is a type of switch that will automatically disconnect if the oil level in the reservoir reaches a certain level

Figure 2.20 Oil level sensing switch

In addition, there are many other types of switches used to interrupt automatic control circuits

A fuse is a device designed to protect an electrical circuit It typically consists of a metal strip or wire placed between two metal terminals When the current exceeds the allowable threshold of the fuse, the metal strip or wire will automatically break to protect the electrical circuit

Figure 2.21 Some kind of fuse

High-current fuse is a thick wire placed in high-current electrical circuits that can burn out when overloaded, thereby protecting the electrical circuit

Because fuses are circuit protection devices, selecting the appropriate power rating and current intensity is crucial

Relays, analogous to switches in electrical circuits, utilize a coil of wire to manipulate switch contacts This unique mechanism reduces the strain on the contacts, enabling control through a low-current coil This action initiates the pulling in of contacts, thereby permitting a high-current flow.

The diagram in Figure 2.23 illustrates the working mechanism of a relay When the switch is closed, the current flows between points 1 and 2 Between points 1 and 2 is a coil of wire, which makes the coil act as an electromagnet The magnetic force of the coil pulls in the movable contact between points 3 and 4 Therefore, points 3 and 4 are closed, allowing the current to flow to the light bulb Thus, by using a relay and a coil, a switch with low power can be achieved

Relays are classified into various types based on how they open or close These types are depicted in Figure 2.24:

This type is normally open and only closes when the coil is energized (A) and (B) in this diagram

This type is normally closed and only opens when the coil is energized (C) in this diagram

This type switches between two contacts, one normally closed and one normally open, which will close when the coil is energized (D) in this diagram

Electricity generation principle

Electromagnetic induction возникает, когда происходит изменение магнитного потока через замкнутый контур проводника Это изменение создает силу, которая заставляет электроны в катушке двигаться, и этот ток называется индуцированным током.

A conductor is placed between the N and S poles of a magnet as shown in Figure

2.25 Then, a galvanometer is connected to the conductor to form a closed circuit When the position of the wire loop between the magnetic poles changes as shown in the diagram, the needle of the galvanometer will deflect

Thus, when the conductor is moved between the magnetic poles, the conductor passes through a change in area and generates a variation of magnetic flux, which in turn generates a current Therefore, if the movement of the wire coil with respect to the magnetic poles remains constant, there will be no change in magnetic flux and no current can be induced

This phenomenon of generating current is called electromagnetic induction, and the current flowing through the conductor is called induced current

Figure 2.25 Electromagnetic induction and right-hand rule

This induced current is generated by the electromotive force resulting from electromagnetic induction Therefore, this electromotive force is called induced electromotive force

Figure 2.25 illustrates the relationship between the direction of the magnetic field, the direction of the induced current, and the direction of movement of the conductor This relationship is known as Fleming's right-hand rule

The principle of a generator is based on the concept of electromagnetic induction

By placing a coil connected to a brush assembly between the poles of a magnet, and then rotating the coil, the contact area of the coil with the magnet's poles will continuously change, thereby generating an induced current inside the coil

The magnitude and direction of the induced electromotive force generated by rotating a coil will change according to the position of the coil Each time the coil rotates halfway, the direction of the current changes because the position of the coil between the poles has been reversed compared to the initial position, thus changing the direction of the current This can be determined using Fleming's right-hand rule

In diagram (1) in Figure 2.26, the current runs from brush A to the light bulb In diagram (2), the power of the current stops In diagram (3), the current runs from brush

Therefore, the current generated by this device is an alternating current Hence, this device is called an alternating current generator

When the switch in diagram (1) is closed or opened, the magnetic flux in the coil will change When this happens, an electromotive force is generated in the coil for a short period To observe this phenomenon more closely, we can move a magnet in and out of a coil as shown in diagram (2)

23 The movement of a magnet into and out of the coil will result in a change in magnetic flux passing through the coil As the magnet approaches, more magnetic lines of force pass through the coil This can be observed by placing an ammeter in the circuit When the magnet moves in, a current flows out of the coil, and when the magnet stops, the current disappears Therefore, changes in magnetic flux induce a current in or interrupt the current through this coil, causing the coil to generate an electromotive force This phenomenon is called self-induction

Applications of this phenomenon can be found in various types of speed sensors, position sensors, and other devices

Two coils are arranged as shown in the diagram When current flows through one coil (primary coil) is changed, an electromotive force will be induced in the other coil (secondary coil) to oppose the change in magnetic flux in the primary coil The greater the rate of change of current, the larger the induced electromotive force This phenomenon is called mutual inductance

An ignition coil utilizes this effect The coil contains the ignition coil of the car to generate high voltage applied to the spark plug When a constant current flows through the primary coil, no electromotive force is induced in the secondary coil When the primary current is interrupted by turning the switch from the ON position to the OFF position, the magnetic flux created by the primary current is suddenly interrupted Therefore, an electromotive force will be induced in the secondary coil to prevent the magnetic flux from decaying However, to achieve a sufficiently large voltage for the ignition process, it must meet the following requirements:

- Rate of change of magnetic flux:

A rapid change occurring over a short period of time will produce a larger electromotive force

- The greater the change in magnetic flux, the larger the electromotive force

The number of turns in the secondary coil significantly influences the electromotive force (EMF) generated For the same magnetic flux change, a greater number of turns in the secondary coil compared to the primary coil (typically by a factor of 100) results in a higher EMF.

Therefore, to generate a high secondary voltage, the current flowing into the primary coil should be as large as possible, and then this current needs to be abruptly interrupted within a short period of time, usually by a transistor.

Multimeter

Multimeter is a common electronic measuring device used to measure basic electrical parameters in a circuit A multimeter typically can measure the following parameters: Current (Ampere): Measures the current flowing in the circuit, often measured across different ranges to match the current in the circuit

25 Voltage (Volt): Measures the voltage between two points in the circuit, providing information about the voltage of the source or components in the circuit

Resistance (Ohm): Measures the resistance of components or the circuit Resistance can be measured across different ranges to match the resistance of the component

Continuity Test: A multimeter can also be used to check whether a circuit is continuous or not, meaning it checks whether there is conductivity between two points

When measuring a specific quantity such as resistance, alternating current voltage, direct current, etc., it is necessary to select the appropriate measurement range to ensure accurate measurement and prevent damage to the multimeter

5.2 Measure the voltage of alternating current

To measure the voltage of power supply lines in households or factories, circuits with alternating current, and output voltages of power transformers

Set the function selector switch to the voltage measurement range of alternating current and connect the test leads The test lead terminals can be interchanged

Because the characteristic of alternating current is it have a 3 phrase so when the multimeter is at the directed current, it can read exactly the voltage, it will change continously

Figure 2.30 Measure the voltage of alternating current

5.3 Measure the voltage of directed current

To measure the voltage of various batteries, electrical devices, and transistor circuits, as well as voltage levels and voltage drops in circuits

Figure 2.31 Measure the voltage of the battery

Set the function selector switch to the DC voltage measurement range Place the negative probe, black in color, to the negative terminal, and the positive probe, red in

27 color, to the area being tested, then read the measurement value Note on reading values: The displayed value will be the voltage difference between the red and black terminals, rather than the voltage at the red probe measurement point This can be easily confused when measuring voltage The multimeter will indicate the voltage difference between the two terminals, not the voltage at the red probe measurement point

To measure the resistance of a resistor, continuity in a circuit, short circuits (0 Ω), and open circuits(∞)

Set the function selector switch to the resistance/continuity measurement position Then place the test leads on each end of a resistor or coil to measure resistance Select the appropriate range for the resistance being measured to obtain an accurate reading Ensure that no voltage is applied to the resistor at this time Diodes cannot be measured in this range In the case of continuity measurements, ensure that the resistance value is within the allowable range specified by the electrical device manufacturer Depending on the device, the resistance value may range from 0 to less than 1 Ω

To check the diode for the good function of blocking 1 direction of the current

Apply a small test voltage (2mA) across the two terminals of the diode, then measure the two terminals of the diode If the diode is forward biased, the voltage difference between the Anode and Cathode terminals should be in the range of 0.5-0.8V for silicon diodes and 0.2-0.3V for germanium diodes, and there should be no value when swapping the test leads This indicates that the diode is functioning normally

If the diode has a value beyond 0 in both directions, it is short-circuited If it has no value in either direction, it is open-circuited

To measure the current consumption of devices operating with direct current

Set the function selector switch to the current measurement range To measure the current of a circuit, connect the ammeter in series with this circuit Therefore, isolate a section of the circuit to connect these test leads Connect the positive test lead to the side with higher voltage and the negative test lead to the side with lower voltage, and read the measured value

Electrical device

Electronics is the science and technology related to the study and application of electronic devices and circuits It involves understanding how electrons move and interact within different materials and components, as well as how they are used to create and control electronic devices

Electronic devices typically include transistors, diodes, integrated circuits (ICs), and microprocessors These devices are widely used in everyday applications such as computers, mobile phones, telecommunications systems, and many other consumer electronic devices Electronics not only focuses on fundamental theories but also on developing new technologies and applications to improve the performance, reduce size, and enhance the functionality of electronic devices

A semiconductor is a type of material with electrical resistance higher than that of good conductors like copper or iron, but lower than that of insulators like rubber or glass The two most commonly used semiconductor materials are Germanium (Ge) and Silicon (Si) However, in their pure state, these materials are not suitable for practical semiconductor applications For this reason, they must be doped with impurities a small amount of additional substances to enhance their practical utility

• When their temperature increases, their resistance decreases

• Their electrical conductivity increases when mixed with other substances

• Their resistance changes when exposed to light, magnetism, or mechanical stress

• They emit light when a voltage is applied, etc

Semiconductors can be divided into two types: N-type and P-type

Figure 2.36 Electrical device Figure 2.35 Resistance of material

An N-type semiconductor consists of a base material, such as silicon (Si) or germanium (Ge), that has been doped with a small amount of arsenic (As) or phosphorus (P), both of which have a valence of 5 These atoms form covalent bonds with the base material atoms (one P atom bonds with four Si atoms), leaving one extra negatively charged free electron This free electron can move easily through the silicon or germanium The "n" in N-type semiconductor stands for "negative," indicating the presence of these free negative charges

On the other hand, a P-type semiconductor consists of a base material, such as silicon (Si) or germanium (Ge), that has been doped with gallium (Ga) or indium (In), both of which have a valence of 3 These atoms form covalent bonds with the base material atoms (one Si atom bonds with four In atoms), creating "holes," which can be considered as "missing" electrons These holes act as positive charge carriers and move in the opposite direction to the free electrons The "p" in P-type semiconductor stands for

"positive," indicating the presence of these positive charge carriers.

Diodes

Semiconductor diodes consist of an N-type and a P-type semiconductor joined together

Figure 2.39 shows how current flows through a diode

- Forward Bias: When the positive terminal (+) of the battery is connected to the P- side and the negative terminal (-) is connected to the N-side, the positive charge carriers (holes) in the P-type semiconductor and the positive terminal of the battery repel each other Similarly, the negative charge carriers (free electrons) in the N-type semiconductor and the negative terminal of the battery repel each other, pushing them towards the p-n junction As a result, the free electrons and holes attract each other, allowing current to flow through the p-n junction

- Reverse Bias: When the battery terminals are reversed, the positive holes in the P- type semiconductor and the negative terminal of the battery attract each other, and the free electrons in the N-type semiconductor and the positive terminal of the battery attract each other, pulling them away from the p-n junction This creates a depletion region at the p-n junction, preventing current from flowing through

Standard diodes allow current to flow in only one direction: from the P-side to the N- side A minimum voltage is required for current to flow from the P-side to the N-side

This current will not flow if a voltage is applied in the reverse direction (from the N- side to the P-side) Although a very small current, called reverse leakage current, does flow, it is treated as negligible because it does not affect the circuit's operation However, if this reverse voltage is increased sufficiently, the current flowing through the diode will suddenly increase This phenomenon is called diode breakdown, and the voltage at which this occurs is called the breakdown voltage

When AC voltage is applied to a diode:

During the positive half-cycle (segment (a) to (b)), the voltage is applied in the forward direction, allowing current to flow through the diode

During the negative half-cycle (segment (b) to (c)), the voltage is applied in the reverse direction, preventing current from flowing through the diode

As a result, only half of the AC current generated by the generator is allowed to pass through the diode

When the polarity of the generator terminals (A and B) changes, the direction of current flow also changes This results in the output current flowing consistently in one direction across the resistor R.

Rectifier diodes are commonly used as rectifiers in AC generators

34 These diodes allow the conversion of alternating current (AC) into direct current (DC), which is essential for powering many types of electronic devices and for charging batteries The full-wave rectification process ensures that the entire input waveform, both positive and negative halves, is used to produce a consistent DC output

Zener diodes allow current to flow in the forward direction, similar to regular diodes However, they can also conduct reverse current in the case of a reverse voltage within the specified Zener voltage threshold for the diode

Forward current flows from the positive side to the negative side through a Zener diode just like a regular diode Reverse current flows when the voltage applied across the Zener diode exceeds its breakdown voltage and is within the diode's limit This is known as the Zener voltage, which remains constant in practice, regardless of the current's intensity A Zener diode can be specified with different breakdown voltages to serve as a voltage regulator according to its purpose

Zener diodes find application in various scenarios, with one of the most significant being their use in voltage regulators for alternating current generators The output voltage is regulated consistently by incorporating Zener diodes into an electrical circuit

LEDs are P-N junction diodes just like regular diodes They emit light when a current passes through them in the forward direction LEDs can emit light in various colors such as red, yellow, and green

LEDs possess the following characteristics:

• They generate less heat and have a longer lifespan compared to conventional incandescent bulbs

• They produce light efficiently with low power consumption

• They respond to low voltage (fast response time)

LEDs are used in various high-mounted brake lights and indicators, etc

An optical diode is a p-n junction diode consisting of a semiconductor material and a lens Optical diodes operate on the principle that when light shines on the P-N junction layer, it generates charges, resulting in a current flow If a reverse voltage is applied to the optically illuminated diode, a reverse current will flow The intensity of this current will vary proportionally with the energy of the photons absorbed in the junction region

In other words, an optical diode can determine the intensity of light by detecting the intensity of the reverse current when a reverse voltage is applied

Optical diodes are used in light sensors for solar panels in air conditioning units, etc

Figure 2.47 Application of optical diode

Transitor

A transistor is a fundamental electronic component comprising three layers of semiconductor material—a P-type layer sandwiched between two N-type layers, or vice versa Each layer is connected to an electrode, designated as Base (B), Emitter (E), and Collector (C) Transistors are categorized into two types, NPN and PNP, based on the arrangement of their semiconductor layers These devices fulfill crucial functions in electronic circuits.

In an NPN transistor, when the current IB flows from the Base (B) to the Emitter (E), the current IC flows from the Collector (C) to the Emitter (E)

In a PNP transistor, when the current IB flows from the Emitter (E) to the Base (B), the current IC flows from the Emitter (E) to the Collector (C)

The IB current is called the base current, and the IC current is called the collector current Therefore, the IC current flows when IB current flows

38 NPN transistors are commonly used for control signals due to their reverse biasing characteristics, such as in ignition systems and fuel injection

PNP transistors are typically used for amplification circuits due to their forward biasing characteristics, similar to amplifiers Transistors used in amplification circuits are often equipped with heat sinks because amplification circuits usually have very high power

Transistors operate similarly to relays but with superior switching frequencies and better reliability because they don't have physical contacts

In a transistor, the relationship between the collector current (IC) and the base current (IB) is depicted in this diagram Transistors typically serve two basic functions: As shown in Figure line "A", it can describe the ability to amplify signals, and line "B" describes the ability to function as a switch

In line "A" of this graph, the collector current is typically 10 to 1000 times larger than the base current Therefore, using the base as the input signal (IB), the output signal at the collector (IC) is amplified

In a transistor, the collector current (IC) will flow when there is base current (IB) Therefore, base current can be turned "ON" and "OFF" by turning the base current (IB) on and off This characteristic of the transistor can be used as a switch

Transistors are used in numerous circuits such as fuel injection systems, ignition systems, and logic circuits within ECUs (Engine Control Units)

Both NPN and PNP transistors perform the same functions; they can both be used as amplifiers or switches in logic circuits However, for convenience and suitability in circuit installation, NPN transistors are typically connected closer to the ground (negative supply), while PNP transistors are usually installed near the positive supply

Figure 2.50 Injector circuit and vehicle speed sensor

When an optical transistor receives light while voltage is applied to its collector and its emitter is grounded, a current will flow through the circuit The intensity of the current passing through the circuit will vary according to the photons absorbed by the collector in the optical transistor Therefore, the light shining on this transistor functions similarly to the base current in a regular transistor

In automobiles, optical transistors are used in deceleration sensors, among other applications, ect

Figure 2.52 Appication of optical transistor

Op-Amp

A comparator compares the voltage of the positive input (+) with the negative input (-) If the voltage of the positive input A is higher than the voltage of the negative input

B, the output Y will be 1 If the voltage of the positive input A is lower than the voltage of the negative input B, the output Y will be 0

IC (Integrated Circuit)

An integrated circuit (IC) is a compact assembly of numerous electrical circuits composed of transistors, resistors, capacitors, and diodes fabricated onto a small silicon chip, offering advantages over discrete circuits ICs exhibit versatile capabilities and specialized functions, including the ability to compare logic signals, amplify input voltages, and perform various other tasks The integration of multiple circuits within a single IC package reduces size, enhances efficiency, and improves reliability, making them widely employed in electronic systems ranging from complex microprocessors to simple digital watches.

• Since many components can be mounted on a single silicon chip, the number of contact connections can be significantly reduced, leading to fewer failures

• They are much smaller and lighter

• Production costs are much lower

An IC containing a large number of components, from 1,000 to 100,000, is called an LSI (Large Scale Integration) An IC containing more than 100,000 components is called VLSI (Very Large Scale Integration)

Digital and analog signal

Understanding digital and analog signals will help us use measuring devices effectively and accurately, which is beneficial for calibration and repair purposes Every circuit in vehicle need 2 signal to operate: INPUT and OUTPUT

INPUT: is a signal to provide the information about the operating condition (usualy is switch and sensor)

OUTPUT: is a signal to make a electric and electrical device operate (lamps, LEDs, relay, motor, )

Electronic Signals can be divided into 2 types: digital and analog

Both INPUT and OUTPUT can be a digital or analog signal depend on its operation

Analog signals change continuously and smoothly over time Therefore, the common characteristic of analog signals is that their output changes proportionally to their input

Figure 2.55 Waveform of analog signals

A throttle position sensor or temperature sensor

• Using 1 continous variable resistance to change the internal resistance

• Change the internal resistance make the voltage change relatively and create the analog signal

• This signal can be any value from 0 to the battery voltage (0-12V) or ECU voltage (0-5V)

• These voltage values will be converted into actual values according to look-up tables in the ECU

Figure 2.56 Application for analog signal

Digital signals is the signal that just have 2 voltage levels This two level represent for two states This signal is not continous and can be express in these ways

In automotive circuits, digital signal usually express as 0V for OFF and 5V (some circuit is 12V) for ON

Usually digital signal have a level to distinguish the ON/OFF state, for 5V circuit it is 3.3V, if the signal over this value the ECU will read it is ON state (5V) and if it below ECU will read it at OFF state (0V)

ECU can receive and provide the the voltage follow the characteristic of the digital signal:

• Signal frequency from the times per second that signal change

• Signal duration (from the time signal at ON state or OFF state)

• Duty circle (percent of ON state time over OFF state time)

Power steering pressure switch and vehicle speed sensor

Figure 2.58 Application of digital signal

Logic Circuits

Digital integrated circuits (ICs) contain various elements The circuits within a digital

IC are called logic circuits or digital circuits and consist of a combination of different types such as NOT, OR, NOR, AND, and NAND gates Because these gates have special capabilities to process logic of two or more signals, they are also referred to as logic gates A logical relationship is established between the inputs and outputs of digital signals A truth table presents the relationship between the inputs and outputs of digital signals

Figure 2.59 Logic circiut on IC

A NOT gate has an output that is the inverse of the input signal When a voltage is applied to input terminal A, no voltage is transmitted at output terminal Y

A circuit with a similar function to a NOT gate is as follows: When switch A is closed (ON), it opens (OFF) the contacts within the relay, causing the light to turn off

Figure 2.61 Diagram and circuit for NOT gate

In an OR gate, the output signal will be 1 when at least one of the input signals is 1 When a voltage is applied to either or both of the input terminals A and B, there will be a voltage at the output terminal Y

A circuit with a similar function to an OR gate is as follows: When either or both switches A and B are closed (ON), the light will illuminate

Figure 2.63 Diagram and circuit of OR gate

A NOR gate is a combination of an OR gate and a NOT gate The output signal at output terminal Y will be 1 only when both input terminals A and B are 0 The output signal at output terminal Y will be 0 if either or both input terminals A and B are 1

For an AND gate, the output becomes "1" (logic HIGH) only when both input signals are "1" (logic HIGH) In this configuration, when voltage is applied simultaneously to input terminals A and B, a voltage is produced at the output terminal labeled Y.

Figure 2.66 Diagram and circuit of AND gate

A circuit with a similar function to an AND gate is as follows: The light will not illuminate unless both switches A and B are closed (ON)

A NAND gate is a combination of an AND gate and a NOT gate The output signal at output terminal Y will be 1 if either or both input terminals A and B are 0 The output signal at output terminal Y will be 0 if both input terminals A and B are 1

ECU

The ECU receives signals from input devices, processes these signals by converting them from analog or voltage forms into predefined converted values to display on screens or control output devices

INPUT: from switch and sensor and send to ECU

• These signal to announce with ECU the status of the system that is under the control

• Provide information about the operating condition and the command of the driver OUTPUT: from ECU and control many systems in the vehicle

An ECU consists of a CPU (central processing unit), various types of memory, and an I/O interface (input/output)

Memory includes circuits to store operating programs or exchanged data There are two types of memory: ROM (read-only memory) and RAM (random-access memory) ROM cannot be altered or erased Therefore, data stored in ROM will not be lost even when power is cut off ROM memory is used to store programs that do not need to be changed or erased, these instructions are programmed and stored from the manufacturer and programmed in a map format to accurately control actuators RAM is a type of memory where data can be changed or erased Any data stored in RAM will be lost when the power is cut off RAM memory is used to store data that can be changed or erased through calculations performed by the CPU

This CPU is the processing center of the ECU, consisting of control mechanisms and parts for calculation, comparison, and execution of logical operations It can also transmit data to other parts of the vehicle It executes commands based on pre- programmed signals from input devices and controls output devices

An I/O interface converts data from input devices into signals recognizable by the CPU and memory Additionally, it transforms data processed by the CPU into signals recognizable by output devices As data transmission speeds vary between I/O devices, the CPU, and different memory components, one of the functions of the I/O interface is to regulate these speeds

Example: 1 kind of ECU is ECM (Engine Control Module)

ECU controll the engine by these INPUT

The ECM receive these signal to control OUTPUT is:

Figure 2.70 ECU input and output signals

Overview question

Use the diagram in Figure 1.71 to complete these activities:

• Write the names of the symbols in the blank spaces provided on the diagram

• Identify whether switch and relay contacts are open or closed Write your answer on the diagram

• Fill in the correct term for the question about transistor current

• Determine whether the crossing wires are connected or not connected Write your answer on the diagram

In the back-up lights circuit above:

• Use a red pen or pink highlighter to trace current in the positive (source) side of the circuit

• Use a green pen or highlighter to trace current in the negative (ground) side of the circuit

Analyze the circuit to predict available voltage at the back-up lights switch and at the right back-uplamp Write those values on the wiring diagram

In the Horn circuit above:

• Use a red pen or pink highlighter to trace current in the positive (source) side of the circuit

• Use a green pen or highlighter to trace current in the negative (ground) side of the circuit

Analyze the circuit to predict available voltage at the horn relay connector and at the low horn lamp Write those values on the wiring diagram

In the fog lights circuit on the previous page:

• Use a red pen or pink highlighter to trace current in the positive (source) side of the circuit

• Use a green pen or highlighter to trace current in the negative (ground) side of the circuit

56 Analyze the circuit to predict available voltage at the fog light relay and at the right hand fog lamp Write those values on the wiring diagram

Exercise 5: Input and Output Signals

Complete the following statements by filling in the blanks:

1 signals provide information about operating conditions

2 _ signals cause an electrical or electronic device to operate

3 Electronic control units (ECUs) typically receive both signals and signals

4 An analog signal is a continuously variable _

5 A throttle position sensor is a resistor and produces an

6 In a typical automotive electronic circuit, a digital signal is either _ or

List the characteristics of a digital signal that can be used to convey information:

List four sensors in the engine control system:

List four devices controlled by output signals from an ECU:

Battery

Battery Classification

In automobiles, two types of batteries can be used for starting: acid batteries and alkaline batteries However, acid batteries have been the most common and widely used Compared to alkaline batteries, acid batteries have higher electromotive force for each cell, lower internal resistance, and provide better starting performance, although alkaline batteries do offer several advantages

Acid batteries come in different types:

➢ Ventilated Batteries: These batteries have vents for checking the battery's status

➢ Low-Maintenance Batteries: These types allow for the addition of electrolyte

➢ Maintenance-Free Batteries: These are sealed batteries where adding electrolyte is not possible

➢ Sealed Batteries: These do not have vent caps, making it impossible to check the condition or add electrolyte Some models feature an indicator to check the battery’s charge level

Battery Construction

Automotive batteries comprise battery cases housing compartments filled with sulfuric acid and positive and negative plates Typically, lead-acid batteries utilize lead or lead-based materials for their plates The battery consists of multiple cells (typically six), each containing numerous plates submerged in the electrolyte solution.

The battery case is designed to hold and protect the internal components of the battery and to contain the electrolyte Typically, the case is divided into six compartments, each with support ridges to prevent the plates from short-circuiting if any material falls

Figure 2.78 Construction inside the case

The basis for the operation of a battery is its cells Each cell comprises negative and positive plates immersed in an electrolyte solution These groups of negative and positive plates are interleaved and separated by separator plates Combined, the plates and separators form a cell of the battery Each cell outputs a voltage of approximately 2.1V, regardless of size

The battery capacity is usually 12.6V, which requires connecting six cells in series to achieve this voltage level

The negative and positive plates are connected to each other and to the battery terminals

Positive Plate: The positive plate is made from antimony coated with a layer of active lead dioxide (PbO2)

Negative Plate: The negative plate is made from lead coated with a layer of active spongy lead (Pb)

The separator is a metal plate used to separate the negative plate from the positive plate to prevent short circuits

The electrolyte in a battery is a mixture of sulfuric acid (H2SO4) and distilled water (H2O) The electrolyte reacts with the materials on the plates to generate voltage The electrolyte solution in modern batteries has a specific gravity of 1.270 (at 20°C) when fully charged Specific gravity is the weight of a volume of liquid compared to the

62 weight of the same volume of water The higher the specific gravity, the denser the liquid

A hydrometer is used to measure the specific gravity of the electrolyte solution The electrolyte in a charged battery is stronger and heavier than the electrolyte in a discharged battery

Figure 2.82 Electrolyte Precautions When Using Batteries:

Handle batteries with caution due to the corrosive sulfuric acid electrolyte Wear protective gear to prevent skin and eye injuries In case of contact, rinse with water and seek medical attention for eye exposure During charging, hydrogen gas release poses fire and explosion risks; keep the battery away from flames and sparks.

Most modern batteries are designed with a row of vent caps that can cover multiple cells The vent cap row is designed to allow acid vapors to condense and fall back into the battery while allowing hydrogen gas to evaporate during the charging process, whether charging with an onboard charger or an external charger

Battery terminals are the points of contact between the battery and external devices They are typically made of metal to ensure good conductivity The battery in a vehicle is responsible for providing power to the starting system with a very large current Therefore, battery terminals need to be robust, capable of handling high currents, providing good conductivity, and securely connecting even in cases of vehicle vibration

Markings on battery terminals indicate positive or negative polarity Typically, "+" denotes the positive terminal, and "-" denotes the negative terminal Sometimes, the markings "POS" and "NEG" are also used to signify positive and negative terminals Markings are meant to ensure proper connection, preventing reverse polarity which could adversely affect the operation of devices and potentially lead to fire or explosion hazards

Battery clamp heads can be made of steel or lead depending on the manufacturer

The specific gravity viewing port utilizes a float that can measure the specific gravity of the electrolyte solution in a cell

Figure 2.85 Status of battery follwing the color of the viewing port

Operation of battery

• Electrochemical Reaction in Battery Cells

When two dissimilar metals are placed in sulfuric acid solution, they generate an electromotive force between the two electrodes The positive electrode (anode) is made of lead oxide (PbO2), while the negative electrode (cathode) is made of lead (Pb) The electrolyte solution is a mixture of sulfuric acid and water Together, these components form one cell of the battery

Batteries serve as energy storage devices, converting chemical energy into electrical energy to power devices This process involves chemical reactions that generate electricity As batteries discharge, they undergo a loss of chemical energy and require recharging This is achieved by reversing the chemical process through the application of a reverse current, restoring the battery's energy capacity The continuous repetition of this charging and discharging process is known as the battery cycle.

Each cell produces an approximate voltage of 2.1V, regardless of the size and number of electrodes An automotive battery typically consists of six cells connected in series, resulting in a total voltage of 12.6V

In batteries, two characteristic chemical processes typically occur in reverse during charging and discharging, and are represented by the following equation:

During discharge, the electrodes from PbO 2 and Pb transform into PbSO 4 Thus, during discharge, sulfuric acid is consumed to form lead sulfate (PbSO 4 ), while water is produced Consequently, the concentration of H 2 SO 4 solution decreases

Changes in the concentration of the electrolyte solution during charging and discharging are one of the indicators used to determine the battery's state of charge during use

There are four stages in the discharge-charge cycle:

• The positive plate is coated with lead dioxide (PbO2)

• The negative plate is coated with spongy lead (Pb)

• The electrolyte contains water (H2O) and sulfuric acid (H2SO4)

• Current flows through the cell from the negative plate to the positive plate

• The electrolyte separates into hydrogen (H2) and sulfate (SO4) ions

• Sulfate ions combine with lead (both lead dioxide and spongy lead) to form lead sulfate (PbSO4)

• Hydrogen and oxygen combine to form additional water, diluting the electrolyte

• Both plates are fully sulfated

• The electrolyte is primarily diluted into water

• The chemical reaction during discharge is reversed

• Sulfate ions (SO4) leave the positive and negative plates and combine with hydrogen (H2) to form sulfuric acid (H2SO4)

• Hydrogen bubbles form at the negative plates; oxygen appears at the positive plates

• Free oxygen (O2) combines with lead (Pb) at the positive plate to form lead dioxide (PbO2).

Lead-Acid Battery Specifications

The electromotive force (EMF) of a battery primarily depends on the potential difference between the two electrode plates when no external current is flowing

The electromotive force also depends on the electrolyte concentration, which can be determined experimentally by the formula:

• E 0 : Static electromotive force of a single battery (in volts)

• ρ: Electrolyte concentration (in g/cm³) at 25 o C

• 𝑡: Temperature of the solution at the time of measurement

•  measure : Electrolyte concentration at the time of measurement

The starting battery for a car must be capable of starting the engine and providing reserve power to operate other systems in the vehicle during startup

• The amount of electrical energy that a battery can provide when fully charged

• It is determined by the size and number of electrodes as well as the volume and concentration of the electrolyte

Each vehicle will have another specification we can find it in the manufacturer’s manual for each particular car

Cold Cranking Amps (CCA) is an important metric to consider when selecting a battery for cars, primarily for starting purposes

During a vehicle's startup, the battery must deliver a substantial current The measurement of its capacity to provide this current is known as Cold Cranking Amps

The Cold Cranking Amps value (measured in Amps) indicates the battery's ability to discharge current when fully charged:

• While maintaining at least 1.2V per cell (12V for battery's six cells)

Batteries designed for typical vehicles usually have Cold Cranking Amps ratings ranging from 350 to 560 Amps, depending on the vehicle type or engine size

Reserve Capacity (RC) denotes the capability of providing electricity to ignition and lighting systems, as well as other vital systems, in the event of a malfunction in the charging system

The rated Reserve Capacity (measured in minutes) gauges how long a fully charged battery can:

• Discharge at a 25 Amp rate while keeping a minimum voltage of 1.75V per cell (and 10.6V collectively for 6 cells in a 12V battery)

Typically, batteries for standard vehicles have rated Reserve Capacities spanning from 55 to 115 minutes, depending on the vehicle type

Battery voltage, expressed in volts, represents the potential difference between its positive and negative terminals While commonly specified in round numbers like 6V, 12V, and 24V, batteries often produce a voltage output higher than their nominal voltage Moreover, the battery's voltage is directly related to its capacity.

This voltage conversion table applies specifically when the battery is at rest, i.e., not under load, indicating it is not actively supplying current Hence, if a 12V battery is rated at a voltage equal to or higher than 12.7V, it indicates a fully charged status A battery is considered depleted when its voltage drops to 10.5V, yet manufacturers typically set a higher voltage threshold to halt operation to prevent rapid plate damage, a consequence of complete battery depletion

Figure 2.88 Capacity bar voltage conversion table

Battery capacity, measured in Ampere-hours (AH), signifies the battery's capability to discharge electricity

The AH rating reflects the discharge capacity of a fully charged battery over a 20- hour duration

• Maintaining a voltage of 1.75V per cell (10.5V for a 12V battery's 6 cells) For exxample: If a battery can deliver 5A over 20 hours, its rated capacity is 80 Ampere-hours

70 Typically, car batteries have capacities ranging from 40 to 80 Ampere-hours, varying based on the vehicle type.

Battery Inspection and Maintenance

• The battery warning light illuminates

These are the most obvious signs that your car battery is experiencing issues It's important to take your vehicle to maintenance and repair centers to check the battery's condition before it becomes inoperable

• Engine Doesn't Turn Over, No Lights on Dashboard:

If you turn the key to start the engine but there's no response, and none of the dashboard lights come on, it's likely that the battery is completely dead, or there could be a problem with the alternator or electrical system

• Weak Starting of the Engine:

A feeble engine start or a complete failure to start can be a strong indication of a weak battery Should you experience difficulty starting your vehicle, consider checking the battery's condition as it is a common root cause of such issues.

1 Check for cracks in the battery casing and broken terminals This could lead to electrolyte leakage If found, replace the battery

2 Inspect for frayed cables or loose connections and replace them if necessary

3 Examine for corrosion on the battery terminals, dirt, and acid on the battery surface If the terminals are severely corroded, use a wire brush

4 Check the battery hold-down bracket and tighten if necessary

5 Check the electrolyte level in the battery Inspect from the outside or remove the caps Add distilled water as needed, but do not overfill

6 Inspect the electrolyte for cloudiness or discoloration, which could be caused by overcharging and sulfation Replace the battery if this is the case

The charging status of the battery can be easily checked using one of the following methods:

Specific gravity refers to the exact density A hydrometer can be used to compare the precise density of the electrolyte solution with water The electrolyte solution with a higher concentration in a charged battery will weigh more than the electrolyte solution

72 with a lower concentration in a discharged battery The electrolyte solution is a mixture of acid and water with a specific gravity of 1.27

By measuring the specific gravity of the electrolyte solution, we can determine whether the battery is fully charged, needs recharging, or requires replacement

Table 1 Specific gravity of the electrolyte depending on charged percentage

• The Specific Gravity Variation between Cells:

The specific gravity difference between cells should not exceed 0.05 This difference is compared between the highest and lowest cell A battery should be replaced if the variation exceeds 0.05 In the example below, the specific gravity difference between the electrolyte solution in the first cell and the fifth cell is 0.07 Therefore, the battery needs to be replaced The fifth cell is defective

Cell No.1 Cell No.2 Cell No.3 Cell No.4 Cell No.5 Cell No.6

Several factors can contribute to variations between cells For example, when initially filling the cells with water, it may dilute the electrolyte solution, resulting in a lower specific gravity reading Charging the battery before taking measurements will provide accurate results

• Procedure for Checking Specific Gravity

3 Squeeze the bulb of the hydrometer and insert the suction end into the cell closest to the positive terminal

4 Slowly release the bulb, drawing up enough electrolyte solution to float the hydrometer inside

5 Read the specific gravity value on the hydrometer Ensure the hydrometer floats completely

6 Record the value and repeat the process for the remaining cells

Observation Procedure at the Observation Window:

2 Observe the hydrometer installed inside the battery

• Green observation point: the battery is fully charged

• Dark green observation point: the battery needs charging

• Light yellow observation point: the battery is defective and needs replacement

Using a voltmeter to check the battery voltage when it's open-circuited is recommended Analog voltmeters are not accurate and should not be used for this purpose

Figure 2.92 Checking Open Circuit Voltage

• To check the open circuit voltage of the battery

1 Ensure the vehicle is turned off and all electrical loads are switched off

2 Use a digital voltmeter to measure the voltage across the battery terminals

3 Place the positive (red) probe on the positive terminal of the battery and the negative (black) probe on the negative terminal

4 Read the voltage displayed on the voltmeter

5 Compare the voltage reading with the manufacturer's specifications to determine the battery's state of charge

A fully charged 12V battery typically reads between 12.6 and 12.8 volts Deviations from this range, particularly lower readings, can signify the need for recharging or indicate the battery's impending end of life.

If your vehicle suddenly stops running, turn off the engine to conserve battery power Initially, the battery voltage may be higher than normal due to the sudden stop To regulate the voltage, turn on the headlights for a few minutes, allowing the battery to discharge and return to its normal operating voltage.

• Checking the battery's high load capacity

When checking the battery's charge status, it does not provide information about the battery's ability to deliver current when starting the engine Testing the battery's load capacity reveals its ability to supply electrical current.

Checking for electrical leaks

Parasitic load, also called parasitic current, is the small amount of electrical current that continues to drain from the vehicle’s battery even when the engine and all

75 accessories are turned off This current is necessary to maintain essential functions like the clock, computer memory, and security systems, which need to stay active even when the car is not running

However, if the parasitic current is too high, it can gradually deplete the battery, causing starting issues or a dead battery A normal parasitic draw is usually less than 35 milliamps (mA) If it exceeds this level, it could indicate an electrical problem that needs to be fixed to avoid draining the battery

• Ensure the vehicle is off and all accessories are turned off

• Disconnect the negative battery cable

• Connect a digital multimeter (set to measure current) between the negative battery terminal and the disconnected cable

• Observe the reading A normal parasitic current is typically less than 35mA If the reading is higher, identify and address the source of the excessive draw

Surface discharge can occur when the surface of the battery is moist or dirty, creating a conductive path between the battery terminals Below are the steps to check and remedy surface discharge

• Place one probe of a digital multimeter (set to measure voltage) on the positive terminal of the battery

• Place the other probe on the surface of the battery, near the negative terminal

• If the measured voltage is greater than 0.5V, there may be surface discharge

Figure 2.93 Check the parasitic current

Figure 2.94 Check the surface discharged Note:

When disconnecting the vehicle battery, an initial surge in parasitic current can occur as the onboard computers and electrical circuits are briefly activated This temporary increase in current consumption typically lasts from a few seconds to 30 minutes, allowing the systems to perform necessary functions before entering a deactivated state During this activation period, it is crucial to exercise caution to avoid electrical hazards or damage to sensitive components.

To efficiently test the battery, refrain from disconnecting it if feasible Place one ammeter probe on a battery post and the other on the battery cable's end Proceed to disconnect the battery cable at this juncture.

To assess battery self-discharge, utilize a digital voltmeter Connect its negative probe to the battery's negative terminal and its positive probe to the battery case's surface If the voltage exceeds 0.5V, clean the case with a baking soda and water solution, followed by a water rinse.

6.3 Check voltage drop at the battery terminals

The resistance between the battery terminals and the battery clamps is also a concern with batteries Despite appearing normal, metal oxidation and minor corrosion can create significant resistance at the connection points, leading to voltage drops and reduced current flow to the starter motor The battery terminals and clamps should be cleaned regularly during battery checks

➢ To check for voltage drop at the battery terminals:

1 Connect the positive (red) probe of the multimeter to the positive terminal of the battery

2 Connect the negative (black) probe of the multimeter to the positive clamp of the battery cable

3 With the vehicle in the OFF position and no loads active, measure the voltage

4 A normal voltage drop should be minimal, typically below 0.2 volts

5 If the voltage drop exceeds 0.2 volts, there may be resistance or corrosion in the positive battery cable, clamps, or connections

6 Check the connections for corrosion, looseness, or damage and repair or replace as necessary

Figure 2.95 Check the voltage drop at terminal

Battery maintenance

Over time, sulfuric acid will corrode the battery terminals, clamps, and hold-downs This corrosion creates resistance and impedes the flow of current to and from the battery Remove the clamps from the terminals and clean them You can use a battery terminal cleaning brush with both a rounded and flat head, ideal for cleaning terminals and clamps

• Adding water to the battery:

It is rare that we add water to the battery, but when we do, we only use distilled water Minerals and chemicals commonly found in regular drinking water can react with the battery's electrode materials and reduce its lifespan Under normal conditions, water is not necessary, but it becomes essential in cases of overcharging, causing water to evaporate from the electrolyte solution

All battery chargers operate on the principle of supplying a current to the battery to facilitate chemical conversion within its cells Avoid connecting or disconnecting the charger when it is turned on Follow the manufacturer's instructions when charging Do not attempt to charge a frozen battery electrolyte When using a charger, always disconnect the battery ground cable This minimizes the risk of damage to the alternator and electronic components in the vehicle A battery can be considered fully charged when all cells release gas and the specific gravity of the electrolyte remains constant for over an hour Slow charging is typically 5 to 10A, while fast charging is 15A or higher Slow charging is preferred

➢ General guidelines for battery charging:

• Always keep the caps open during the charging process

• Always follow the manufacturer's instructions

• Always charge the battery in well-ventilated areas, wearing eye protection and gloves

• Always avoid exposure to sparks and flames (Avoid smoking nearby)

• Charge rate should match the discharge rate Fast discharge requires fast charging, slow discharge requires slow charging (If in doubt, opt for slow charging)

• Never charge while the battery is installed in the vehicle Remove the battery before charging Excessive charging voltage can damage electrical devices in the vehicle

• Check the specific gravity of the electrolyte periodically

• Check the battery temperature during charging by touching the side surface If it's too hot, stop charging and let it cool down

Before removing or installing the battery:

For optimal safety during battery removal, it is crucial to park the vehicle on a flat surface Additionally, donning gloves and safety glasses is mandatory prior to initiating the process.

79 Remember the PIN codes of electronic devices before removing the battery This helps facilitate reprogramming after installing the new battery more conveniently

Step 1: Completely turn off the ignition system to prevent any risk of fire or explosion Wear gloves and safety glasses to ensure safety for your hands and eyes

Figure 2.97 Turn off the key

Step 2: Identify the location of the car battery Ensure that the positive terminal is covered before removing the negative (-) cable Then proceed to remove the positive (+) cable

Figure 2.98 Loosen the bolts or nuts securing the battery terminals

Step 3: Remove the battery hold-down clamp or bracket, and then carefully lift the battery out of the vehicle

Figure 2.99 Remove the battery hold-down bracket Note:

Removing the positive terminal of the battery first may cause the vehicle's electrical system to short circuit When removing the battery, ensure that all battery connection components are detached from the battery tray on the vehicle The weight of the battery can range from 15 to 20 kg for some product models

Step 1: Use a clean cloth to wipe the battery terminals and battery tray Clean the battery terminals thoroughly, and then reinstall the battery back into its original position

Figure 2.100 Fix the battery position

Step 2: Gently place the new battery into the battery tray of the vehicle Use a wrench to connect the battery terminals to the new car battery The sequence for connecting the terminals is: Positive terminal first, followed by the negative terminal

Figure 2.101 Attach the terminal and install the fixing bar

Step 3: Spray anti-corrosion solution onto the battery terminals to prevent corrosion buildup

Figure 2.102 Spray battery anti-corrosion solution

Step 4: Close the hood securely and start the vehicle to ensure that all components are functioning properly.

Testing the Battery with Hantek Battery Test

The Hantek Battery Test device is specifically designed for testing various types of batteries, including activated lead-acid batteries This device can assess the battery's condition through the testing process, charging, and discharging, and then accurately analyze the battery's status, displaying the results on the screen for mechanics to understand the battery's condition Hantek supports the testing of dynamos, starters, and batteries for the maintenance process conducted by Toyota technicians

8.2 Operation of Hantek Battery Test Device

Turn off the engine and set the system to the OFF state

If your car battery is reading higher than normal after recent use, it's advisable to turn on the headlights for a couple of minutes This will allow the battery to discharge and stabilize its voltage By doing so before testing the battery, you can ensure an accurate reading, as the initial high voltage reading can be misleading.

Connect the red cable to the positive terminal and the black cable to the negative terminal of the car battery

• Checking the starting ability of the battery:

Press to select the function

Select “Start ability” to check the starting ability of the battery

Then select the battery value standard according to the specifications on the battery and adjust the settings to match the manufacturer's values

Figure 2.104 Setting for battery testing

＞80% Good Good condition: Battery is in optimal working state

＞60% Common Usable condition: Battery is functional but not in peak condition

＞45% Attention Warning condition: Battery shows signs of potential issues and may soon need attention

＜45% Replace Replacement needed: Battery is in poor condition and should be replaced

Table 2 Result status of the battery measuring by the Hantek device

Cold Cranking Amps (CCA): This value is used to determine the state of the battery and represents the amount of current the battery can provide The higher the CCA, the lower the internal resistance of the battery The closer this number is to the manufacturer's specified value, the better the battery's condition

State of Health (SOH): This metric indicates the battery's health and overall performance SOH is a crucial specification for evaluating the battery's condition An SOH of 100% means the battery's health and performance are at their peak, typically seen in newly manufactured batteries Over time, the SOH will gradually decrease

In the initial selection menu, choose “Start Load,” then press Enter and start the vehicle

The tester will then display the results of the starting process

Starting voltage Battery discharge efficiency Solution

Above 10.7V Good No replacement required

9.6~10.2V Bad Needs to be replaced

Below 9.6V Very Bad Needs immediate replacement

Table 3 Starting load result measuring by the Hantek device

Review question

Exercise 1: Identifying and Naming the Components of a Battery

Refer to the drawing of a battery in Figure 2.32 Match the numbers on the drawing to the correct component names below:

Exercise 2: Associating Battery Component and Function

Refer to the list you made in Exercise 1 Match each of these functions with the associated component Write the component’s number in front of the function statement:

Allows checking of the battery’s electrolyte level and state of charge Provides a connection point for the battery cable

Separates and insulates battery plates from each other

Is a mixture of sulfuric acid and water

Houses and protects all the internal components and electrolyte

Can be removed to add water to the electrolyte

Is made of lead and takes part in the chemical reaction that produces electricity

Starting System

Functions of starter

Since internal combustion engines cannot start on their own, an external force is required to initiate their operation To start the engine, the starter motor rotates the crankshaft via the flywheel ring gear The starter motor must generate a large torque

86 from the limited electrical power of the battery while remaining compact and lightweight For this reason, a direct current (DC) electric motor is used in the starter

Starting an engine requires crankshaft rotation exceeding a minimum rotational speed, which varies by engine design and operating conditions Gasoline engines typically necessitate 40 to 60 RPM (revolutions per minute), while diesel engines require 80 to 100 RPM Establishing these minimum rotational speeds ensures successful engine startup.

Types of Starter

Automotive starter motors come in diverse types with varying designs and efficiencies Gear-reduction, conventional, planetary gear, and planetary reduction segment conductor starters each serve specific vehicle requirements Their unique advantages and disadvantages dictate their suitability for different applications, ensuring optimal engine starting and economic efficiency for manufacturers.

Principle of Starter

Figure 2.111 Forces are created between the magnets

Based on the interaction of magnetic forces between magnets, a starter motor is created When a freely rotating magnet is placed between two continuously changing

89 magnetic poles, the attraction and repulsion of the magnetic poles cause the magnet in the middle to rotate continuously around its axis (as shown in Figure 3.6)

In real engine, the magnet in the middle is replaced by a wire coil supplied with electricity Suppose we have a wire coil wound as shown in Figure 3.6 When the wire coil is supplied with electricity, an electromagnetic field is generated, and this electromagnetic field is considered as a magnet

The direction of the magnetic lines of force which are generated in the wire coil is determined by the right-hand rule (corkscrew rule)

Figure 2.112 Wire Coil in a Magnetic Field

Place the wire coil on a pivot so that it can rotate However, it can only continue to rotate if the force generated is in the same direction Therefore, by attaching a commutator and brushes to the wire coil, we can change the direction of the current in the wire coil, thereby altering the magnetic force which are generated in the wire coil

Figure 2.113 Magnetic Lines of Force of the Wire Coil and Magnet

By attaching a commutator and brushes to the wire coil, the current runs from right to left and changes direction from left to right, causing the wire coil to become an electromagnet with reversible poles This action causes the magnet to continue rotating

Figure 2.114 The electromagnetic force generated on the wire coil

Applying this theory in practice, one must first wind multiple wire coils to increase the magnetic flux and thereby generate a larger torque Next, a steel core is placed inside the wire coils to magnetize the core and transform it into an electromagnet

Instead of using permanent magnets, electromagnets can serve as the field component The relationship between the electromagnet's poles and the current flowing through it can be explained using the right-hand rule Curl the fingers of the right hand in the direction of the current Then, the four remaining fingers touching the palm will indicate the electromagnet's South pole

To achieve high-speed and smooth motor rotation, multiple wire coils are employed

The armature coil is wound as Figure 11, with the two ends of the adjacent wire coils soldered to the same copper segment on the commutator The current flows from the positive brush to the negative through the wire coils connected in series

When viewed from the Bendix gear, the direction of the current aligns as Figure 12

The direction of the current passing through the wire coils within the same quadrant of the rotor remains consistent Consequently, the direction of the magnetic field generated in each coil remains unchanged as the commutator rotates

Figure 2.117 Current Flow in Rotor

The arrangement of wire coils in the field and armature sections generates electromagnetic force that rotates the armature Direct current motors are categorized into three types based on their winding configurations:

• Series-wound type: This type produces the highest torque at startup and is primarily utilized in starter motors due to its ability to deliver substantial initial torque

• Parallel-wound type: Exhibiting minimal speed fluctuations, similar to permanent magnet motors, this type is known for its stable operation

• Compounding-wound type: Combining characteristics of both series and parallel winding configurations, this type is commonly employed for starting large engines, offering a balance between torque and speed regulation

Figure 2.118 Types of winding configurations

2.4 Relationship between speed, torque and current intensity

Fundamentally, the electrical circuit of a motor consists primarily of wire coils The resistance value within the circuit is minimal due to the resistance of the wire coils

According to Ohm's law, the current value will significantly increase when the battery voltage (12 V) remains constant and the circuit's resistance is very low Consequently, a large current is directed to the starter motor, generating maximum torque as soon as the starter begins operate

93 Since the structure of a motor and a alternator are similar, a counter-electromotive force (back EMF) is generated when the motor rotates, which reduces the amperage This induced EMF increases as the speed of the starter motor rises, thereby decreasing the current passing through the motor and subsequently reducing both the torque and the current

- The gear ratio between the drive gear and the ring gear is approximately between 1:10 and 1:15

- The output power of the starter motor is initially very low when it begins operation due to high torque and low speed However, this power increases to its maximum value as the torque and speed of the starter motor change, and then it decreases The starter motor's power is represented by a curve in Figure 14, plotted against the variations in torque and speed of the starter motor

2.5 Relationship between current and voltage

When the starter begins operate, the voltage at the battery terminals decreases due to the increased current in the circuit With a high current in the circuit, a voltage drop will occur across the internal resistance of the battery According to Ohm's law, this voltage drop increases as the current in the circuit rises Conversely, the voltage drop decreases as the current in the circuit diminishes, allowing the battery voltage to return to its normal value.

Structure of starter

A reduction gear starter motor comprises the following components:

1 Bendix Gear and Helical Splines

3.2.1 Bendix Gear and Helical Splines

The Bendix gear enables rotational force transmission from the starter motor to the engine via the fly-wheel's ring gear Its beveled design allows smooth meshing, while the helical spline converts rotational force into thrust force This thrust assists in the effortless engagement and disengagement of the Bendix gear with the ring gear.

Figure 2.121 Bendix Gear and Helical Splines

95 The reduction gear transmits the rotational force of the motor to the Bendix gear and increases torque by reducing the motor's speed The reduction gear decreases the motor's rotational speed with a ratio of 1/3 to 1/4 and contains over-running clutch within it

The armature generates the force that rotates the motor, and the ball bearing supports the armature core, allowing it to rotate at high speeds

Figure 2.123 Armature and ball bearing

96 The starter’s yoke generates the necessary magnetic field for the motor to operate It also has a function as a protective cover for the field coils and pole core, enclosing the magnetic flux lines The field coils are connected in series with the armature

This component generates the necessary magnetic field for the starter This type of starter uses an electromagnet as the field component by winding excitation coils (are wrapped by the isulation layer) around the pole core This type of field component is commonly used in reduction gear and conventional starter For PS-type starter, permanent magnets are used as the field component

Springs press brushes against the armature's commutator, ensuring current flow from coils to the armature in a specific direction These brushes are composed of copper-carbon composites, combining high electrical conductivity and wear resistance The brush springs' pressure against the commutator halts armature rotation upon starter motor disengagement.

If the brush springs weaken or the brushes wear down, the electrical contact between the brushes and the commutator may become insufficient This increases the resistance at the contact point, reducing the current supplied to the motor and consequently decreasing the torque

Figure 2.125 Brush and Brush Holder

The solenoid switch functions as the main contact, controlling the flow of current from the battery to the motor and managing the Bendix gear by pushing it into engagement with the flywheel at startup and retracting it afterward The pull-in coil is wound with thicker wire than the hold-in coil, resulting in a greater electromagnetic force compared to that generated by the hold-in coil The solenoid switch serves two primary functions:

- It acts as a wire, allowing direct current from the battery to flow into the motor

- It enables the Bendix gear to engage with and disengage from the flywheel

- If there is an open circuit in the pull-in coil, it will not be able to attract the piston, preventing the starter motor from starting (no audible activation of the solenoid switch)

- If the main contact has poor contact, the current flow to the field coil and armature will be restricted, reducing the starter motor's speed

- If there is an open circuit in the hold-in coil, it will not be able to hold the plunger in place, potentially causing the piston to engage and disengage continuously

An over-running clutch is employed in the starter assembly to transmit motion from the motor to the flywheel through the Bendix gear This one-way clutch, featuring wedged rollers, safeguards the starter from damage during high rotational speeds once the engine starts As the Bendix gear shaft accelerates beyond the clutch's outer ring's speed, the rollers and springs disengage the shaft from the clutch's outer casing, protecting the starter from excessive stress.

The engagement and disengagement mechanism

The engagement and disengagement mechanism is crucial for starting and running an engine Firstly, it engages the Bendix gear to drive the flywheel and initiate engine startup Once the engine starts, this mechanism disengages the Bendix gear to prevent the flywheel from rotating the starter in reverse This is essential because the engine speed after startup exceeds the starter's capacity, potentially damaging the starter motor.

The Bendix gear and the ring gear mesh together due to the attracting force of the solenoid, compressing the return spring and driving the armature to rotate slowly as current flows from the pull-in coil Subsequently, the main contact is engaged, and the rotational force of the armature increases Part of this rotational force is converted into a pushing force on the Bendix gear due to the torsional action of the shaft Both the Bendix gear and the ring gear are chamfered to facilitate smooth engagement

After the engine started, the rotational speed of the engine (flywheel) becomes higher than that of the Bendix gear during engine startup, causing the flywheel to drive in the opposite direction to the Bendix gear Part of this rotational force is converted into a thrust force along the axis by torsional action to disengage the meshing between the Bendix gear and the flywheel gear

The over-running clutch mechanism prevents the flywheel's rotational force from driving the starter in the opposite direction Once the engine has started, the magnetic switch is turned off, causing the magnetic attraction of the magnetic switch to be lost

As a result, the compressed return spring will push the Bendix gear back to its original position, disengaging the meshing between the two gears Consequently, the Bendix gear is easily pulled out of engagement.

Operation of starter

When the ignition switch is turned to the START position, the battery current flows into the hold-in coil and the pull-in coil Subsequently, the current passes from the pull- in coil to the field coil, then to the armature, and finally to ground, causing the armature to rotate at a low speed due to the limited current passing through the pull-in coil The electromagnetic force generated in the hold-in and pull-in coils magnetizes the pole cores, causing the plunger of the magnetic switch to be attracted to the pole cores of the electromagnet This attraction pushes the Bendix gear outwards, engaging it with the flywheel ring gear while simultaneously activating the main switch via the contact disc

To maintain the voltage required to activate the magnetic switch, some vehicles employ a starter relay positioned between the ignition switch and the solenoid switch

When the main switch is activated, no current flows through the pull-in coil because both ends of the pull-in coil are at equal potential The field coil and the armature receive direct current from the battery The armature begins to rotate at high speed, starting the engine At this point, the plunger remains in position solely due to the electromagnetic force of the hold-in coil, as no current flows through the pull-in coil

103 When the ignition switch is turned from the START to the ON position, the main contact remains closed At this moment, the current flows from the main switch to the pull-in coil and then through the hold-in coil The pull-in and hold-in coils are designed with the same number of windings and are wound in the same direction At this point, the current flowing through the pull-in coil is reversed, causing the electromagnetic forces generated by the pull-in and hold-in coils to cancel each other out, thereby failing to hold the piston Consequently, the piston is pushed back by the return spring, and the main switch is disengaged, stopping the starter motor

Figure 2.134 Structure of Over-running clutch

When starting, the armature and the clutch housing rotate together with the inner shaft This causes the wedged rollers to be pushed into the narrow part of the groove, thereby transmitting the rotational force of the armature to the inner shaft

Figure 2.135 Operation of Over-running clutch (Engine Starting)

As the inner shaft surpasses the rotational speed of both the armature and clutch housing, wedged rollers are impelled into the wider portion of the groove This action triggers the Bendix gear and inner shaft to disengage from each other, allowing for free rotation.

Figure 2.136 Operation of Over-running clutch (Engine Started)

Detailed information of various types of starter

106 The construction of the magnetic switch in conventional starter is fundamentally similar to the gear-reduction starter However, in this type, the magnetic switch pulls the plunger to engage the bendix gear through a shift lever and disengages it, whereas in reduction gear starters, the plunger is pushed to perform this action

The function of the shift lever is to transmit the motion of the magnetic switch to the bendix gear Through this motion, the bendix gear is engaged and disengaged with the ring gear of the flywheel

The return spring is positioned within the shift lever or within the magnetic switch The return spring of the conventional starter operates similarly to the return spring of the gear-reduction starter

The conventional starter employs a large armature to generate ample torque, eliminating the need for a reduction mechanism Consequently, the armature is directly coupled to the Bendix gear, enabling the starter to engage the flywheel and initiate engine rotation without any intermediate gear reduction.

Conventional starters are often outfitted with a braking mechanism that prevents motor operation in the event of an engine failure Additionally, this mechanism serves to regulate the motor's high speed upon engine startup.

Some conventioal and gear-reduction starter do not have a braking mechanism for the following reasons:

- The armature has a small mass and low inertia

- The brush pressure is large

- The reduction mechanism generates frictional force

The brake spring and brake disc push the armature bar into the end frame to create braking force

6.2.1 Engagement and Disengagement of the Drive Gear

The return spring is located within the magnetic switch This spring functions similarly to the return spring in both the gear-reduction starter and the conventional

107 starter The magnetic switch and the shift lever operate in the same manner as those found in the conventional starter

The drive carrier of the planetary gear set contains three planetary gears These planetary gears mesh with the sun gear (driven by the armature) on the inside and with the ring gear on the outside Typically, the ring gear is fixed

The planetary gear set boasts an impressive reduction ratio of 1:5, leading to a more compact and high-speed armature compared to traditional starter motors To maintain seamless performance, the ring gear is typically crafted from specialized plastic Furthermore, the design incorporates a clever mechanism that effectively absorbs surplus torque, safeguarding the ring gear from potential damage.

When the sun gear is driven by the armature, the planetary gears rotate around the fixed ring gear, causing the carrier to turn As a result, the speed of the carrier and the planetary gears decreases, increasing the torque transmitted to the Bendix gear

By rotating the ring gear, the clutch disc engages with the ring gear, which then slips and absorbs the excess torque

6.3 Planetary Reduction Segment Conductor (PS)

Figure 2.143 Field componet of PS Starter

109 The PS starter uses permanent magnets instead of field coils like the conventional and reduction types To generate the maximum total magnetic flux while shortening the length of the motor housing, both main magnets and interpolar magnets are utilized to complement each other Additionally, this arrangement helps to reduce the overall length of the motor yoke

Instead of using round-shaped conductors like in the case of conventional starter, PS- type starter employ square-shaped conductors In this configuration, square-shaped conductors can achieve similar conditions as round-shaped conductors but in a more compact manner As a result, the torque is increased while the winding coil becomes more compact Due to the square-shaped conductors, the commutator is also the armature Consequently, the overall length of the PS-type starter motor casing is shortened

Figure 2.144 Armature of PS Starter

Inspection and repair

• Ground test the armature coil

Using a circuit tester to check for the insulation between the commutator piece and the armature core Placing the iron piece (a saw-like one) on the armature fitted to the layer short tester and turn the armature by hand If the iron piece vibrates, it implies a short circuit, it means the isulation layer peel off, causing the wire loops contact to each other This results in the closed circuit

Within a rotor, wire loops envelop its exterior Due to the tester's design, the number of magnetic flux lines entering the rotor's core equals those exiting it This equilibrium results in the generation of electromotive forces (emf) and back electromotive forces (back emf), effectively canceling each other and preventing current flow through the windings However, when wire loops become shorted, a closed circuit is established, disrupting this balance and allowing current to flow The subsequent magnetic field generated by this current attracts the saw blade, causing it to adhere to the rotor's surface.

• Continuity Testing of Rotor Coils

Measure the resistance according to the value(s) in the table below:

Tester Connection Condition Specified Condition

Segment - Coil Core Always 10 kΩ or higher

Figure 2.149 Continuity Testing of Rotor

113 Use a vernier caliper to measure the outer diameter of the commutator Grinding the outer surface of the commutator if there are any irregularities

Place the commutator on V-blocks, using a dial indicator, measure the circle runout

Manually rotate the bearing, listen for any unusual noises, and feel for any irregular movement

Figure 2.152 Inspeting the ball bearing

• Inspecting the continuity of the yoke

Measuring the resistance between the lead wire and brush

Figure 2.153 Inspecting the continuity of the yoke

Tester Connection Condition Specified Condition

Lead wire - Brush Always Below 1 Ω

Table 4 Measuring the resistance between the lead wire and brush

• Inspecting the isulation of the yoke

115 Measuring the resistance between the yoke and brush

Figure 2.154 Inspecting the isulation of the yoke

Tester Connection Condition Specified Condition

Table 5 Measuring the resistance between the yoke and brush

Using a vernier caliper, measure the brush length

• Inspect the insulation of brush holder:

Measure the resistance according to the value(s) in the table below:

Negative (-) Brush Holder Always 10 KΩ or higher

Table 6 Measure the resistance between the Positive and Negative brush holder

Figure 2.156 Inspect the insulation of brush holder

• Inspecting the brush spring load:

Take a pull scale reading immediately after the brush spring separates from the brush

Figure 2.157 Inspecting the brush spring load

• Inspecting the over-running clutch

117 Rotate the Bendix gear clockwise and check that it turns freely Try to rotate the Bendix gear counterclockwise and check that it locks If the result is not as specified, replace the over-running clutch

To determine the condition of the over-running clutch, manually rotate the Bendix gear while applying inward force Observe the movement of the bearing If resistance is encountered or the bearing becomes stuck, it indicates a faulty over-running clutch In such circumstances, replace the over-running clutch to ensure proper starter engagement and prevent any further issues.

Figure 2.158 Inspecting the over-running clutch

• Inspecting the holding and pull-in coil

Figure 2.159 Inspecting the holding (left) and pull-in coil (right)

Measure the resistance according to the value(s) in the table below:

Terminal 50 - Switch Body Always Below 2 Ω

Table 7 Measure the resistance between Terminal 50 and Terminal C / Switch body

If the result is not as specified, replace the magnet starter switch assembly

Applying grease points and tightening torque value of starter

Checking the voltage

8.1 Checking the voltage of battery

When the starter is in operation, the voltage at the battery terminals decreases due to the high current intensity within the circuit Even if the battery voltage is normal before starting the engine, the starter may not function properly unless a certain voltage level is maintained when the starter begins to operate

Therefore, it is necessary to measure the battery terminal voltage while the engine is starting

- Turn the ignition key to the START position and measure the voltage of the battery

- If the measured voltage is lower than 9.6 V, the battery must be replaced

If the starter is malfunctioning, it's crucial to inspect the battery's condition Normal battery voltage readings alone are insufficient, as corrosion or rust on the terminals can hinder starting This increased resistance diminishes the voltage reaching the starter upon ignition, impeding its operation.

8.2 Checking the voltage of terminal 30

Turn the ignition key to the START position and measure the voltage between terminal 30 and the ground point

If the voltage is lower than 8.0 V, the starter cable must be repaired or replaced

The location and configuration of terminal

30 may vary depending on the type of starter motor, so it is necessary to check and correctly identify this terminal according to the repair manual

Figure 2.161 Checking the voltage of battery

Figure 2.162 Checking the voltage of terminal 30

8.3 Checking the voltage of terminal 50

Turn the ignition key to the START position and measure the voltage between terminal 50 of the starter motor and the ground point

If the voltage is lower than 8.0 V, inspect the fuse, ignition switch, neutral / parking switch, starter relay, etc., at the moment Refer to the circuit diagram, repair, or replace any faulty components:

- The clutch switch of the starter in the vehicle does not engage unless the clutch pedal is fully depressed

Anti-theft systems in automobiles prevent the starter from engaging when activated The starter relay remains deactivated, rendering the ignition key ineffective in the START position, thus deterring unauthorized vehicle operation.

Starting by the smartkey system

9.1 Introduction to the Smartkey start system

The Smartkey start system is an anti-theft engine immobilizer device that possesses numerous useful features and is gradually replacing traditional keys

• Start/Stop Button and Smartkey: Instead of starting the vehicle with a key, users utilize an electronic authentication device called a Smartkey When brought near the vehicle within a certain range, the Smartkey sends a signal to the internal antenna assembly, and the Smartkey system analyzes and decodes this signal The encrypted chip connects to the engine through the ECU to confirm the key code If the code is correct, the ECU allows the vehicle to start when the user presses the Start/Stop button

• High security: When a vehicle is equipped with a start/stop button and Smartkey system, only the Smartkey containing the programmed code can unlock the vehicle If an incorrect key is used, the system prevents the engine from starting even when the Start/Stop button is pressed The ignition and fuel injection processes will not be executed Compared to using traditional key, using the Smartkey system provides much higher security

• Engine start/stop via button: In addition to high security, the Smartkey start system also offers many convenient features When using the Smartkey start system, you don't

Figure 2.163 Checking the voltage of terminal 50

121 need to insert the key into the ignition switch each time you start the vehicle The Smartkey automatically sends a signal to the ECU If the key encryption is correct, you simply need to press the Start/Stop button to start the vehicle Similarly, turning off the engine only requires pressing the Start/Stop button

• Remotely door lock and unlock: Using the buttons on the Smartkey, you can remotely lock or unlock the doors, and open or close the windows Some Smartkey systems also have a feature to automatically unlock the doors when the Smartkey is near the vehicle within a radius of 1-5 meters Similarly, when the Smartkey moves away from the vehicle beyond 1-5 meters, the system automatically activates the door locks

• Alarm when detecting forced entry: The Smartkey system has a steering wheel lock function and can detect abnormal external forces acting on the vehicle when the doors are locked

9.2 Main components of the Smartkey system

Figure 2.164 Main components of the Smartkey system

10 ESCL (Electrical Steering Column Lock)

This is a module within the Smartkey (SMK) system Its components include two pairs of normally open contacts that convey the driver's intentions to the Power Distribution Module (PDM) The presence of two pairs of contacts serves to enhance the reliability of the button; if one pair encounters a failure, the other pair will continue to function In such cases, the system must be started using the "double start" mode

The Start/Stop button functions similarly to Key Fob Holder when starting in LimpHome mode (or Engine Failsafe Mode) Additionally, it provides signals 1 and 2 for the 12V activation process from the SMK unit When the button is pressed, the signal grounds, and the SMK unit interprets the signal sequentially as ACC/ON

To start the engine, besides the engine switch is pressed , the following condistions must be satisifed:

- The gear lever is in the N (Neutral) or P (Park) position

- The brake switch is ON (the brake pedal is pressed)

When the engine switch is pressed, the ignition switch position will change in the following sequence: OFF→ START

If the brake is not pressed, the ignition switch position will be: OFF → ACC → ON

No Ignition conditions Start/Stop Button LED status

2 IG ACC Amber color LED ON

3 IG ON (Engine OFF) Blue color LED ON

4 Starting Maintain LED status before cranking

Table 8 Start/Stop Button LED status

The SMK key includes the following main components:

- The mechanical key is used to open the door, trunk, and glove compartment

- The RF (Radio Frequency - 315, 433, 447 MHz) signal transmitter serves to send signals for locking/unlocking the door and trunk

- The LF (Low Frequency - 125 KHz) signal transmitter is used for key localization and identification

- The transponder (CHIP) is used to operate in LimpHome mode when the key is run out of battery or when a system error occurs

The SMK control unit receives signals from the Smarykey, which can be LF (Low Frequency) signals from the localization antennas or signals from the CHIP via the antenna integrated within the LimpHome module

124 After receiving the key signal, the SMK unit will share the identification signals with other control units to verify the conditions for allowing the engine to start

Functions of the SMK Control Unit:

- Activate Antennas to Locate the Smart Key

- Send Lock/Unlock Requests to the ESCL (Electronic Steering Column Lock)

- Recognize the Smart Key Within Antenna Range

- Alert for Smart Key System Errors

The PDM (Power Distribution Module) is a pivotal component that governs power distribution across different vehicle systems It eliminates the traditional ignition key mechanism prevalent in conventional vehicles This module houses relays that allocate power to specific systems, designated as ACC, IG1, IG2, and START, ensuring the smooth operation of various electrical components.

125 During engine starting, the ACC and IG2 power sources are interrupted by relays to concentrate power for engine starting, similar to traditional ignition keys The difference lies in the PDM's ability to store security information from the key

The PDM receives security information from the smart key provided by the SMK unit to jointly determine whether to allow engine starts

This unit serves to receive radio frequency (RF) signals from the Smartkey and transmit them to the SMK module If the data analysis matches the Smarkey code, the SMK module will execute commands such as locking/unlocking doors, opening/closing the trunk, sounding the horn, and activating the lights for the vehicle locating function

The RF receiver has only three electrical wires in its connection to the unit: B+ power supply, ground (GND), and the signal transmission line to the SMK or PDM module

An antenna is a device used for the vehicle to communicate with the Smartkey

It is utilized to both receive and transmit signals to the SMK module for the purpose of locating the Smart Key

The construction of the antenna includes coils of wire for receiving LF (low- frequency) signals and has two wires connected to the SMK module for signal transmission

The location of the antennas:

- Door handle antennas: Locate and identify the keys outside the vehicle to lock/unlock the car doors

- Trunk antenna: Locate and identify keys inside the trunk of the car

- Rear bumper antenna: Locate and identify to allow the owner to open the trunk with a button

- Antennas in the center console and rear seat area: Locate and identify keys inside the vehicle for starting

The Brake Switch plays a crucial role in vehicle safety, ensuring that the SMK module only authorizes engine starting when brake pedal depression is detected Without a functional Brake Switch signal, the control box prohibits starting the vehicle to prevent accidental movement and potential hazards.

Neutral Safety Switch: This switch signals the P or N gear position information to the SMK module as a safety signal for engine starting

The exterior door handle consists of:

- Door Electrical Key Oscillator: Receives request signals from the SMK module, controls the antenna for signal transmission

128 -Touch Sensor: Confirms the action of opening the door, sends signals to the SMK module

- Door Lock Switch: Receives door lock signals, sends signals to the SMK module

The Key FOB Holder is only available in vehicles equipped with the SMK version 2.5 system or earlier It is used for storing keys for starting the vehicle in LimpHome mode and for key registration purposes

The Key FOB Holder, or Limphome Module, consists of a single coil antenna similar to the coil in the Immo system, a key-in switch inside the lock, and a warning light

The Electronic Steering Column Lock (ESCL) is a steering lock module that uses an electric motor to extend or retract a locking bolt, locking or unlocking the steering column based on system status This eliminates manual mechanical operations and enhances safety and security The ESCL holds registered key information in its memory and can connect with other modules via the vehicle's network.

9.3 The operational principle of different Smartkey systems

Figure 2.177 The diagram of the operating principle of Smartkey

To initiate the vehicle's starting sequence, the gear shift must be in P or N and the brake pedal depressed The SMK module verifies key presence by powering the Antenna, which locates the key via signals and transmits them to the RF Receiver The RF Receiver transmits the key code to the SMK module for verification If the key code is correct, the SMK module sends the information to the PDM via the CAN line The SMK module unlocks the ESCL, and the PDM powers Relays IG1 and ST The key code is then verified again through the PCM, which controls fuel injection and ignition If the key code remains correct, the RPM signal deactivates Relay ST and activates Relays ACC and IG2.

When Smartkey run out of battery

When the Smartkey runs out of battery, the driver will place it in the Fob Holder At this point, the Smartkey inside the Fob Holder will send a signal to the PDM to inform that the key is inside the Fob Holder The PDM will then transmit this signal about the key in the Fob Holder to the SMK via the CAN bus When the driver presses the brake pedal, with the gear shift lever in the P or N position, and presses the Start/Stop button, two signals will be sent to the PDM and SMK At this point, the ID retrieval of the key will be handled by the PDM by supplying power to the coil in the Fob Holder and retrieving the key's ID information to send back to the PDM Concurrently, the PDM will send the key's ID to the SMK for confirmation If the key is correct, the SMK will transmit the correct key information to the PDM via the CAN bus, ESCL, and PCM The SMK will send a request to unlock the ESCL, and the PDM will supply power to unlock the ESCL The ESCL will report the unlock status back to the PDM and SMK After confirming that the ESCL is unlocked, the PDM will supply power to Relay IG1 and Relay ST At the same time, the SMK will transmit the key ID through the PCM, and at this point, the key ID confirmation process will occur again If the key ID is correct, the PCM will control the fuel injection, ignition, and send the RPM signal back to the PDM to cut off the power to Relay ST and turn on Relay ACC and IG2

Some common malfunctions and their remedies

The system allows to reach the IG ON mode, and the display shows “Press brake pedal to start engine”

- Starting without pressing the brake pedal: The engine switch is OFF, press the Start/Stop button once (press and release immediately) Pressing the button again and holding for about 10 seconds will start the engine

10.2 Unable to start due to the shift lever is in D position

Figure 2.200 Unable to start due to the shift lever is in D position

When failing in starting engine, and an error appears on the dashboard, if you observe that the gear shift lever is not in the P or N position, then shift it to P or N and try starting again

If the gear shift lever is already in the P or N position but the dashboard still displays

"Shift to 'P' position", then check the electrical circuit

Accompanying this issue is the ability to turn the engine switch to ACC insteads of OFF and the inability to control the door lock

10.3 Unable to start due to the Smartkey battery is low or runs out

Figure 2.201 Smartkey Battery is low

Figure 2.202 The Smarkey is not inside the vehicle

- SMK 2.0: Insert the key into the Fob Holder and then press the Start/Stop button

- SMK 2.5: Insert the Smartkey into the Start/Stop button to start

Unable to start due to a malfunction in the SMK module or ESCL

+ ESCL sends a malfunction signal to the SMK, and ESCL itself does not function + Warning message appears on the dashboard

+ LED light on the start button flashes (orange color for 10 seconds)

+ Cabin warning bell (for 3 seconds with SMK 2.0 and 5 seconds with SMK 2.5) + Error code recorded in the module

+ Engine switch ON, the system fails to recognize the key

+ Immobilizer light flashes (for 10 seconds)

+ Smart key holder LED flashes (for 10 seconds)

+ When the SMK Module malfunctions, the system fails to start up, lock/unlock functions do not work, and resetting the key will display an error indicating no operation

Review question

Exercise 1: Identifying and Naming Components

Refer to the starting system diagram in Figure 3.99 Match the numbers on the drawing to the correct component names below:

Refer to the list you made in Exercise 1 Match each of these functions with the associated component Write the component’s number in front of the function statement:

Provides electrical power to operate the starter motor

Closes to allow current flow to the pull-in and hold-in coils

Closes when current flows through the pull-in coil to provide a large current flow from the battery through the starter motor to ground

(More than one component) Opens when excessive current flows in the circuit

160 Closes when the gear selector is in Neutral or Park

Exercise 3: Identifying and Naming the Components of a Starter

Refer Figure 3.100 Match the numbers on the drawing to the correct component names below:

Exercise 4: Associating Component and Function

Determine whether each of the following statements about PS starters is true or false Write your answer in the blank space in front of each statement

Planetary reduction gears allow the starter motor to operate at a lower speed than a conventional starter motor

The purpose of the reduction gear set is to reduce pinion gear speed compared to motor shaft speed

Segment conductor type starters are more compact than conventional starter motors

Segment conductor type starters are heavier than conventional starter motors

Segment conductor type starters provide greater output torque than conventional starter motors

Charging system

Functions of charging system

Cars are equipped with various electrical systems and devices to ensure safety and convenience during use These systems require electrical power to operate, both while the vehicle is operating and when the engine is off Therefore, they rely on both the battery and a direct current (DC) power source as their energy supply The charging system installed in the vehicle provides DC power to these systems and devices When engine is off, these systems will use the power provided by the battery, causing it to gradually deplete

The Charging system utilizes the rotation of the engine to generate electricity It not only supplies power to the various electrical systems and devices but also charges the battery while the engine is running.

Structure of the Charging system

- Rectifier : Converts alternating current (AC) to direct current (DC)

- Regulator : Adjusts the voltage generated by the alternator

- Battery: Stores and supplies electrical power

- Charging indicator : Alerts the driver to any issues within the charging system

- Engine switch : Connects and disconnects the electrical current to the charging system

Figure 2.205 Structure of the Charging system

163 When the engine switch is turned on, a current flows from the battery to the charging system and the control module of this system will provide current to the rotor This current turns the rotor into an electromagnet As the engine runs, this electromagnet rotates, causing a change in magnetic flux through the stator coil The changing magnetic flux generates an electromotive force (EMF) in the stator coil The electricity generated by the alternator charges the battery and supplies power to the electrical system The charging indicator on the dashboard use to inform that the alternator is not generating electricity or if there is a fault in the charging system.

Functions of the alternator

The alternator uses the engine's rotation to drive the rotor, generating alternating current (AC) through the variation of magnetic flux within it However, the electrical devices and microchips within control units (ECU, PCM, etc.) require direct current (DC) to operate Since the alternator generates electricity using the engine's rotation, if the engine speed is too high,

164 The output voltage can exceed the desired voltage of the loads within the vehicle's electrical system, potentially causing damage To mitigate this issue, a voltage regulator is used In older alternators, the system consisted of a alternator and rectifier, with the voltage regulator being a separate component, either vibrating contact or emiconductor type Nowadays, alternators are ltequipped with integrated microchips voltage regulators To detect malfunctions, alternators are additionally equipped with a charging indicator light control function

The alternator plays a crucial role in electrical supply systems It performs three functions: generates electricity, rectification, and voltage regulation

The engine rotates, transmitting rotational motion to the alternator via a belt The alternator's rotor is supplied with electricity based on the engine speed and the voltage of the battery The generated magnetic field interacts with the winding wire in the stator, inducing electricity based on the principle of electromagnetic induction

To power electrical devices in a vehicle, the alternating current (AC) generated by the alternator must be converted to direct current (DC) This conversion is achieved by the rectifier, which rectifies the AC into DC, enabling the electrical systems to function effectively.

The voltage regulator adjusts the voltage generated by the alternator during operation

It ensures that the voltage delivered to the electrical devices remains constant (12V - 14V) even when the actual voltage produced is significantly higher due to high engine speed.

The operating principle of alternator

There are various methods to generate electricity In alternators, coils and magnets are used to produce electricity in the coil based on the phenomenon of electromagnetic induction The electromotive force generated in the coil increases with the number of coil turns, the strength of the magnet, and the speed at which the magnet moves

When a magnet approaches a coil, the magnetic flux within the coil increases, leading to a counteracting magnetic flux generated by the coil Conversely, as the coil moves away, the magnetic flux decreases, again eliciting a counteracting magnetic flux from the coil This phenomenon arises from the coil's inherent resistance to changes in magnetic flux.

The practical principle of alternator:

Figure 2.211 The practical principle of alternator

- Permanent magnets are replaced by electromagnets, allowing for variable flux

- The addition of a steel core will increase the flux through the coil

- Generated flux from the armature induces continuous flux variations

The relationship between a DC alternator and an electric motor:

Connecting a small light bulb to an electric motor and manually rotating the electric motor, the light bulb glows dimly, demonstrating that the electric motor is constructed similarly to a direct current alternator Mechanical energy and electrical energy can be generated from the same magnet and coil framework

Figure 2.212 The relationship between a DC alternator and an electric motor

When riding a bicycle equipped with a alternator at night, one may notice that pedaling requires more effort This occurs because the alternator functions similarly to an electric motor, generating a force in the opposite direction in addition to its power generation function, thereby requiring greater pedaling force

When the electric motor rotates, it functions like a alternator, generating a reverse current that reduces the current from the battery

When the alternator is operational and connected to an electrical load, it behaves like an electric motor, thus generating a force in the opposite direction that impedes rotation.

Engine immobilizer system

Anti-theft alarm

STATISTICS AND REPAIR OF ALL TRAINING MODELS

PRACTICE SHEETS, DESIGNING MODELS FOR EDUCATIONAL