11111 indd Chapter I Diagnostics of electrical devices Special warnings 1 When carrying out welding work on the vehicle, the connectors of all control units must be disconnected 2 It is strictly forbi.
Howo A7 Electrical equipment Chapter I Diagnostics of electrical devices Special warnings: When carrying out welding work on the vehicle, the connectors of all control units must be disconnected It is strictly forbidden to install a non-standard battery on the car or use an external battery with an increased voltage compared to its normal value when starting the engine! It is strictly forbidden to disconnect the connector of the wiring harness of the control unit with any system when the supply voltage is present on it! During repair work, not touch unnecessarily the contacts on the electrical connectors If necessary, ensure that static electricity is relieved from your hands first! I Wiring diagram of the entire vehicle Description of the wiring diagram A complete wiring diagram of all electrical devices on the vehicle is essential to the successful implementation of repair work What is especially important for difficult situations, a repair specialist needs a circuit diagram in order to make a conclusion about the possible cause of the violation and find ways to solve the existing problem.Thus, the first step towards performing repair work is to familiarize yourself with the complete electrical wiring diagram of the vehicle The electrical circuits of the vehicle use a single-wire circuit (for the electrical devices of the chassis in version 08, a two-wire circuit is used) The nominal voltage in the power circuits is 24V, while the colors of the conductors are coded in capital Latin letters, as shown below: Letter A Color Red B Black C White D Yellow E Grey F G H Green Purple Orange I Blue K L M N Blue Brown Golden Pink Below are fragments of the electrical circuit diagrams of the HOWO7C vehice In accordance with these diagrams, you can find information on the features of the structure of electrical circuits, a list of components, voltage values, a description of the “ground” connection points, etc Howo A7 Electrical equipment A8 Starter power supply S4 G1.G2 Accumulator battery K28 Mechanical type main power switch Main power switch electromagnetic type K2 Terminal 15 # of Power Relay J2 F4,4 F1,1 Fuse in the constant power supply circuit of the contact 13.61kg F4,5 Fuse in the constant supply circuit of terminal 15 # Air dryer fuse Power switch G3 M1 S1 X20 JP3 Alternator Starter Ignition switch Switching unit Deconcentrator S8/28 F1,2 Ignition switch fuse D3.D5 Diode S14 Transmission neutral position sensor F2,1 Fuse in the power supply circuit of the EDC30 # contact Q R6 Heated seat F2,4 Fuse in the power circuit 30 # R11 Air Dryer KK Main relay of the engine management system F2,5 Fuse in the power supply circuit of the EDC30 # contact F50 Fuse 5A PE PCV valve relay F4,3 DC power interface 15 # Seat heating / brake light fuse A Supply voltage B Seat heating, dehumidifier (1) “Negative” battery terminal (41) Left cab ground connection point (43) Right cab ground connection point Figure 6-78 HOWO7C Vehicle Electrical System Diagram Examples of the use of electrical circuit diagrams to solve practical issues in diagnostics A typical malfunction of a car equipped with an engine with an electronic fuel injection control system is Start violation occurs For a Euro II engine, what is the most common cause of a start failure ?Since a start failure on an engine with electronic fuel injection control can be caused by damage not only to the starting circuits, but also by the fact that the engine control unit does not detect a start condition Thus, the engine management system requires a number of healthy electrical circuits, which can potentially be damaged at several characteristic points Below is a description of the power circuits on the HOWO7C car, which allows you to diagnose all their possible malfunctions Howo A7 Electrical equipment Figure 6-79 HOWO7C Vehicle Power Supply Circuit Diagram (1) Description of system operation a The main switch S4 controls the power supply to terminal 30 As a result, power from terminal JPA.1 of the right control unit is supplied to terminal 17 of the engine control unit (ECU) b When the ignition switch S1 is set to the position corresponding to the start of the engine, the supply voltage is supplied to the junction block from the contact JPB.4 of the right control unit along the circuit +15 After the +15 V voltage is applied to the power distributor: 1) The PCV - KP relay is activated, while supply voltage is supplied to the PCV1 and PCV2 components through its closed power contacts 2) At the same time, the supply voltage is applied to terminals 46 and 56 of the engine control unit, while the engine control unit switches contacts 74 and 75 to ground The main relay KE of the engine management system is activated, as a result of which, through its closed contacts, the supply voltage is applied to contact + E of the supply voltage distributor: From contact + E of the power distributor, the voltage through contact XE3.1 is applied to contacts 5, and of the control unit engine • • From contact + E of the power distributor, voltage is supplied via contact XE3.2 to terminals 35 and 76 of the control unit engine • From contact + E of the power distributor, voltage through contact XС1.8 is applied to the neutral position sensor S14 transmissions c When the transmission control lever is in neutral, the contacts of the S14 sensor are closed 1) After terminal LS3.13, the left control unit receives a transmission neutral (high) signal and the LCD displays an N symbol indicating transmission neutral 2) In this case, if the presence of a transmission neutral position signal is detected on terminal 66 of the engine control unit, contact 42 of the engine control unit is connected to ground through its internal circuits, as a result of which contact of relay A8 will also be connected to ground d With the S1 ignition switch in 1st position: 1) Terminal 48 of the engine control unit receives a start signal; 2) A start signal is applied to terminal JPE1.3 of the right control unit 3) In this case, the power contacts of the start relay A8 are closed Howo A7 Electrical equipment e Terminal 50 of starter M1 is supplied with voltage, the starter starts to operate and the starting process begins (2) Engine start relay circuits Separate start button on the vehicle Start relay coil Start relay contacts closed “Positive” terminal of the storage battery Power switch “Positive” terminal of the starter “Positive” terminal of the generator Terminal 30 of the cab wiring harness “Negative” terminal of the storage battery Contact of the starter connection with “ground” Contact 50 of the starter Starter relay contact 10 Internal ground wire of the engine control unit (3) Search for causes of start violation Analysis of the above information shows that various factors can be the causes of start failure To the outside Start-up can be caused by malfunctions of any of the following components The following are the most likely causes of a malfunction: a An open or damaged in the diode D3 circuit, as a result of which the PCV valve is not powered b An open or damaged in the KP relay circuit causing no power to the PCV valve c Open or damaged in the KP relay circuit, as a result of which power is not supplied to the ECM d Damage to fuse F1.2, F2.1, F2.5, F3.4 caused by a breakdown in the electrical circuit e Open or damage in the gearbox neutral position sensor circuit, as a result of which the engine control unit does not allow the engine to start f Damage in the contact circuit of the start mode of the ignition switch, which causes the absence of a start signal g Damage to the winding or contact of the start relay, as a result of which there is no start signal on terminal 50 of the starter h Starter damage i The starter motor works, but the engine does not start, for example due to a malfunction in the fuel supply system II Check and elimination of malfunctions of a combination of devices Assessment of the state of the input and output circuits of the display play a very important role in finding the causes of its malfunctions Therefore, before starting repair work, make sure that the indicated circuits are in good condition The instrument cluster has four important connection lines, the state of which determines the operation of the device This is pin for connecting the 24V supply voltage on the C1 connector (pin 30 # for connecting the power), as well as pin on the C1 connector (LIN communication line circuit, through this contact the left and right control units are connected, the operating voltage is 14-16V) In addition, this is pin on the C1 connector (pin 15 # for connecting the supply voltage from the ignition switch), as well as pin or pin on the C1 connector (ground connection) If there is a malfunction in at least one of the four indicated conductors, the instrument cluster will not be able to work normally The four above function lines are connected to the C1 connector on the back of the instrument cluster These lines are also connected via wiring harnesses and a switching unit to the corresponding terminals on the left and right control units These conductors are connected to the following distribution contacts: terminal 30 # of the junction box, terminal 15 # of the junction box, LIN pins, and a ground connection Howo A7 Electrical equipment Terminal 30 # of the junction box: Fuse F5 - is connected via pin of the JPD connector It is designed to supply power to terminal 30 # of the left control unit and instrument cluster Junction box terminal 15 #: Connected to JPC pin of the right control box (the right control box has a built-in automatic current limiter) and supplies power from terminal 15 # of the ignition switch to the left control box, instrument cluster and switch brake light If the external circuit breaker is activated, the supply voltage to the 15 # circuit is disabled LIN conductor: Pin on the JPC connector of the right control unit is connected to the corresponding conductors for the communication with the left control unit and instrument cluster Contact for connecting “mass” of the switching unit: Connected to the circuits of the “mass” of the left control unit, instrument cluster and rocker switch Symptoms of malfunctions and the procedure for checking the instrument cluster Symptoms of malfunctions: The instrument cluster does not work or the display of information on its screen is not in an appropriate manner Checking procedure: (( with ground conductors connected to them) Make sure that the supply voltage is present on the above conductors, in the absence of voltage, check the reliability of the connection of the above main conductors to the switching unit (2) If the main functional circuits of the instrument cluster are OK, but the device does not work, replace the instrument cluster (3) If the instrument cluster gauge arrows work normally, but the display does not show any information, replace the instrument cluster Symptoms of malfunctions and the procedure for checking various devices of the instrument cluster (1) Symptoms: Speedometer does not work Checking procedure: Disconnect the instrument cluster C2 connector Connect the wire to pin of the C2 connector of the instrument cluster, then briefly touch the indicated wire to the “ground” If the speedometer needle deviates sharply, this indicates that there is no malfunction of the instrument cluster Check the installation of the device, the condition of the signal transmission wires, the ground connection wires and the 12V power supply of the speedometer sensor (2) Symptoms of malfunctions: The tachometer does not work Checking procedure: Disconnect the instrument cluster C2 connector Connect the wire to pin of the C2 connector of the instrument cluster, then briefly touch the indicated wire to the “ground” If the tachometer needle deviates sharply, this indicates that there is no malfunction of the instrument cluster Verify that the alternator has a pulse output on track W, then check the harness connector (3) Signs of malfunctions: Fuel gauge does not work Checking procedure: Use a multimeter to check that the resistance between C2 track and ground is between 10-180 Another test method can be connecting a 100 resistor between the specified contact and contact of the ground connection on the C2 connector If, when the indicated resistor is connected, the pointer arrow moves, this indicates that there is no malfunction of the instrument cluster Next, make sure that the sensor, electrical connectors and ground connections are in good condition (4) Signs of malfunction: Air brake pressure gauge does not work Checking procedure: Using a multimeter, make sure that the resistance between pin of the C2 connector and the “mass” is in the range of 10-184 Another method of verification may be to connect a 100 resistor between the specified con-clock and the mass connection pin on the C2 connector If the pointer needle moves when the specified resistor is connected, this indicates that there is no malfunction of the instrument cluster Howo A7 Electrical equipment Next, make sure that the sensor, electrical connectors and conductors of the connection to the “mass” are in good condition (5) Symptoms of malfunction: Air pressure indicator in the pneumatic braking system does not work Verification procedure: Using a multimeter, make sure that the resistance between pin of the C2 connector and the “mass” is in the range of 10-184 Another method of verification may be to connect a 100 resistor between the specified contact and the mass connection pin on the C2 connector If the pointer needle is moved when the specified resistor is connected, this indicates that there is no malfunction of the instrument cluster Next, make sure that the sensor, electrical connectors and conductors of the connection to the “mass” are in good condition (6) Symptoms of malfunction: The oil pressure indicator does not work Verification procedure: Using a multimeter, make sure that the resistance between pin of the C2 connector and the “mass” is in the range of 10-184 Another method of verification may be to connect a 100 resistor between the specified contact and the mass connection pin on the C2 connector If the pointer needle is moved when the specified resistor is connected, this indicates that there is no malfunction of the instrument cluster Next, make sure that the sensor, electrical connectors and conductors of the connection to the “mass” are in good condition 7) Symptoms of malfunction: Coolant temperature indicator does not work Verification procedure: Using a multimeter, make sure that the resistance between pin of the C2 connector and the “mass” is in the range of 22.7-287.4 Another method of verification may be to connect a 100 resistor between the specified pin and the mass connection pin on the C2 connector If the pointer needle moves when the specified resistor is connected, this indicates that there is no malfunction of the instrument cluster Next, make sure that the sensor, electrical connectors and conductors of the connection to the “mass” are in good condition Signs of malfunctions associated with the disruption of the operation of light alarms and indicators on combinations of applications, as well as the procedure for their verification (1) Symptoms of malfunctions: After starting the engine, the battery charging indicator remains on The verification procedure: Check if there is a generator voltage on pin or pin of the JPE/RS1 connector of the right control unit If there is a voltage, the 43rd numeric parameter on the input display window must be set to “0”, otherwise its value must be “1” (2) Symptoms of malfunction: When the engine is started, the beep is activated and the indicator light of the 1st contact air pressure sensor remains on Verification procedure: Check if the 1st light on the instrument cluster is lit and also make sure that the 25th digital parameter is on on the working window of displaying input signals is set to “1” If the display shows the specified value “1”, check the input circuit from pin on the LS3 connector of the left control unit for a short circuit, and then make sure that the 1st air pressure sensor is working properly (3) Symptoms of malfunction: When the engine is started, the beep is activated and the indicator light of the 2nd contact air pressure sensor remains on Verification procedure: Check if the 2nd light on the instrument cluster is on and also make sure that the 26th digital parameter is on on the working window of displaying input signals is set to “1” If the display shows the specified value “1”, check the input circuit from pin on the LS3 connector of the left control unit for a short circuit, and then make sure that the 2nd air pressure sensor is working properly (4) Symptoms of malfunction: When the engine is started, an audible signal is activated and the indicator light of the contact air pressure sensor remains on Verification procedure: Make sure that the 22nd numeric parameter on the input display window is set to “1” If on the screen the specified value “1” is displayed, check the input circuit from pin 11 on the LS3 connector of the left control unit for short-circuit, and then make sure that the contact air pressure sensor is working properly Howo A7 Electrical equipment (5) Malfunction: When the engine is started, the beep is activated and the indicator light of the contact sensor of the fuel pressure detector remains on Verification procedure: Make sure that the 57th numeric parameter on the input display operation window is set to “1” If on the screen the specified value of “1” is displayed, check the input circuit from pin on the JPE / RS1LS3 connector of the right control unit for a short circuit, and then make sure that the contact sensor of the fuel pressure signal is working properly (6) Malfunction sign: When the engine is started, an audible signal is activated while the illumination light of the cab lock contact sensor remains on Verification procedure: Make sure that the 56th numeric parameter on the input display window is set to “1” If on the screen the specified value of “1” is displayed, check the input circuit from pin 16 on the JPE / RS1 connector of the right control unit for a short circuit, and then make sure that the contact sensor of the cab lock signal is working properly III Checking and Troubleshooting the Control Unit If the instrument cluster is working properly, analyze the possible causes of malfunctions by viewing the operating windows of the input/output signals If it is decided to check all the input and output signals of the system, first make sure that the main function circuits of the left control unit are in good working order and connected correctly, as well as that there is a normal connection between the left and right control units Check the main functional circuits as well as the status of the left control unit: pin or 12 on the LS2 connector of the 24V supply voltage (input circuit 30# supply voltage), pin or 10 on the LS2 connector of the supply voltage of 24V (input circuit 15# supply voltage), pin 21 on the LS2 connector (LIN communication line, it provides a connection of the combination of pri-borons with the right control unit, the voltage in the line is 14-16V), as well as pins or 17, 18, 19 on the LS2 connector (connecting the “mass”) If there is a malfunction in the circuit of at least one of the four specified contacts, the left control unit will not be able to work normally Check the main functional circuits, as well as the status of the right control unit: Pin on the JPC connector (LIN communication line, it provides communication of the instrument cluster with the right control unit, the voltage in the line is 14-16V), as well as pin on the JPC connector of the circuit 15# connecting the supply voltage from the ignition switch and pin on the JPD connector (circuit 30# of the power supply voltage from the battery) If at least one of these three conductors malfunctions, the system as a whole will not be able to work normally Sequence of operations in diagnosing faults of the display control unit (1) Malfunction indication: The display screen displays the message “main control panel unknown”, the car’s systems are generally not working, and the screen is flashing to warn of a malfunction Verification procedure: Check pins and 12 on the LS2 connector of the left control unit for a supply voltage (30#) proCheck pins and 10 on the LS2 connector for the ignition switch supply voltage (circuit 15#) pin 21 (LIN line) on the LS2 connector pins 1, 17, 18, and 19 on the LS2 connector (mass connection) If there is a violation on the above contacts, check the status of the power lines (circuits 15#, 30#) on the switching unit, as well as check for a break in the conductors of the LIN communication line and the reliability of the “mass” connection If the main function lines of the left control unit are working properly, but the signs of a malfunction persist, replace the left control unit (2) Malfunction Symptom: The display screen displays the message “main control panel unknown” Not recognized), but the car’s systems are generally operating normally Verification procedure: Check pin of the C1 connector of the instrument cluster (communication line, operating voltage in the range of 14-16V) if the specified There is a breach of the circuit, check the cab LIN communication line circuit for any faults If no violations are found in the above chains, but there are signs of a malfunction, replace the combination of applications boar Howo A7 Electrical equipment (3) Malfunction Sign: The display screen displays the message “driving plate unknown”, the vehicle’s systems are generally not working, and the screen is flashing to warn of a malfunction Verification procedure: Check pin of the JPC connector of the right control unit (LIN communication line, operating voltage: 14-16V) if there is a violation in the specified circuit, this malfunction will affect the communication between the left control unit and the instrument cluster through the wire connecting pin 21 of the LS2 connectors of the left control unit and pin of the C1 connector of the combi-nation instruments If no violations are found in the above chain, but there are signs of a malfunction, replace the right control unit (4) Malfunction Indication: The display displays the message “main control panel unknown” and only the light indicator and light alarm are working properly Verification procedure: Check pins and 10 on the LS2 connector of the left control unit connected to the power circuit from the ignition switch (circuit 15#) check pin on connector C1 of the instrument cluster (LIN communication line, operating voltage: 14-16V) if there is a violation in the above circuits, check for the supply voltage from the ignition switch (circuit 15#) on the switch unit located below the steering wheel, and the absence of a break when connecting the conductor of the LIN communication line to the specified switching unit If no violations are found in the two above chains, but there are signs of a malfunction, replace the left control unit Signs of malfunction of the JPF connector of the right control unit and the corresponding verification operations / seriality of service procedures (1) Fault indication: The alarm device does not turn on Verification procedure: On the input parameters working window, make sure that the 13th digit parameter is set to If the value is specified The parameter is 1, make sure that there is a voltage of any magnitude on pin of the JPF connector of the right control unit, and check that there is no short circuit or break in the wiring harness, and also make sure that the alarm lamp is not damaged (2) Malfunction Sign: Lifting platform does not work Verification procedure: On the input parameters work window, make sure that the 31st digit parameter is set to If the value is specified 1, make sure that there is any voltage on pin of the LS2 connector in the left control unit If the value of the specified parameter is not set to 1, check what the value of the 12th digit parameter is on the input parameters working window If it is 1, make sure that there is a voltage on pin of the JPF connector in the right control unit In the preliminary case, there is a short circuit or break in the wiring harness of the lifting device If the value of this parameter is not set to 1, make sure that pin 14 of the LS1 connector of the left control unit has a connection to the “mass”, and also make sure that the flip switch is working properly (3) Malfunction: The engine brake in the exhaust system does not work, but when the engine brake switch is pressed, its indicator light turns on Verification procedure: If an “exhaust brake malfunction” message appears on the display screen, check the circuit Pin on the JPF connector of the right control unit for short circuit If there is no fault message on the display screen, check the output circuit of pin on the JPF connector for a break (4) Malfunction: The engine brake in the exhaust system is not working and the indicator light does not turn on when the engine brake switch is pressed Verification procedure: After checking the engine brake switch, make sure that the value of the 29th digital parameter on the working window the input parameters are 1, and then verify that there is an input voltage on pin of the LS2 connector in the left control unit Howo A7 Electrical equipment (5) Fault indication: The power take-off device is not working, the power take-off switch indicator is not lit Verification procedure: After checking the serviceability of the flip switch of the power take-off device, make sure that the value of the 8th digital pair is the meter on the working window of the input parameters is (6) Fault indication: The power take-off device is not working, the power take-off light is flashing Verification procedure: Make sure that the PTO position sensor is working properly If the position sensor signal after onThe power take-off device is not registered by the control unit for seconds, turn off the power take-off device (7) Fault sign: The power take-off device is not working, the power take-off light is on Verification procedure: If on the display screen there is a fault message, check for a short circuit in the output circuit of the conClock speed 11 on the JPF connector of the right control unit If there is no fault message on the display screen, check for a break in the output circuit of pin 11 on the JPF connector of the right control unit (8) Fault sign: The center differential lock is not working, the differential lock indicator is not lit Verification procedure: After checking the serviceability of the switch switch of the center differential lock device, make sure that the value of the switch is The 11th digital parameter on the working window of the input parameters is 1, (9) Fault symptom: The center differential lock is not working, the differential lock indicator is not working Verification procedure: Make sure that the position sensor of the center differential lock device is working properly If the signal is positional The sensor after turning on the locking device of the center differential is not registered by the control unit for seconds, turn off the power of the differential valve between the shafts (10) Fault symptom: The center differential lock is not working, the differential lock indicator is lit Verification procedure: If there is a fault message on the display screen, check for a short circuit in the output circuit Clock speed on the JPF connector of the right control unit If there is no fault message on the display screen, check for a break in the output circuit of pin on the JPF connector of the right control unit (11) Fault sign: The cross-axle differential locking device is not working, the diffuser lock indicator is not lit Verification procedure: After checking the serviceability of the flip switch of the inter-wheel differential lock device, make sure that the switch is significant The 10th digital parameter on the working window of the input parameters is (12) Fault sign: The cross-axle differential lock is not working, the differential lock indicator is flashing Verification procedure: Make sure that the position sensor of the cross-wheel differential lock device is working properly If the position sensor signal is not recorded by the control unit within seconds after turning on the locking device of the cross-axle differential, disconnect the power to the differential valve between the wheels Howo A7 Electrical equipment (13) Fault sign: The cross-wheel differential lock is not working, the differential lock indicator is lit Verification procedure: If there is a fault message on the display screen, check for a short circuit in the output circuit Clock speed 10 on the JPF connector of the right control unit If there is no fault message on the display screen, check for a break in the output circuit of pin 10 on the JPF connector of the right control unit (14) Malfunction: All-wheel drive is not working, the all-wheel drive indicator is not lit Verification procedure: After checking the health of the all-wheel drive flip switch, make sure that the value of the 12th digit parameter is on the working window of the input parameters is (15) Malfunction symptom: All-wheel drive is not working, the all-wheel drive indicator is flashing Verification procedure: Make sure that the position sensor of the all-wheel drive switching device is working properly If the position sensor signal is onAfter turning on the all-wheel drive is not registered by the control unit for seconds, turn off the power to the all-wheel drive valve (16) Fault symptom: All-wheel drive is not working, the all-wheel drive indicator is lit Verification procedure: If there is a fault message on the display screen, check for a short circuit in the output circuit Clock speed 12 on the JPF connector of the right control unit If there is no fault message on the display screen, check for a break in the output circuit of pin 12 on the JPF connector of the right control unit (17) Fault sign: There is no transition to the neutral position of the power take-off device (before that the power take-off device was working) Verification procedure: if the value of the 9th digit parameter on the working window of the input parameters does not match make sure that the input parameters are correct flip-up power take-off switch If the value of the 9th digit parameter on the input parameters window is 1, and a malfunction message appears on the display screen, check for a short circuit “mass” in the circuit of pin on the JPF connector of the right control unit If there is no invalidity message on the display screen, check for a break in pin on the JPF connector of the right control unit Signs of malfunction of the JPG connector of the right control unit and the corresponding verification operations / consistency of service procedures (1) Fault sign: The air conditioner is not working Verification procedure: if there are no fault messages on the display screen check for a supply voltage on the pin JPG connector, and also make sure there is no break in the power supply circuit of the air conditioner If a malfunction message appears on the display screen before the engine starts, such as “air conditioner malfunction”, check the fuse F5_3 and relay J3 If the message “air conditioner branch circuit over-current” appears on the display screen, make sure that there is no short “mass” in the external circuit from pin on the JPG connector (2) Fault sign: Wiper function violation Verification procedure: If the wiper does not restart, make sure the J7 relay has pins In addition, when the windshield wiper is operating Make sure that the power supply voltage appears periodically on pin of the JPG connector of the right control unit In the opposite case, check the windshield wiper motor restart circuit and the electrical connector 10 Howo A7 Electrical equipment C10 Position of the combination switch (left turn indicator switch) IN_DIG_16 D, 8mA, пprogrammable level C11 Reversing light switch IN DIG 17 D, 8mA, пprogrammable level C12 Lighting control IN_DIG_18 D, 8mA, programmable level C13 The signal starts the engine IN_DIG_19 C14 MCAN_L_TR Not Used C15 MCAN_L Not Used C16 MCAN_GND Not Used «Ground» IN_DIG_20 D, 8mA, programmable level IN_DIG_21 D, 8mA, programmable level IN_DIG_22 D, 8mA, programmable level IN_DIG_23 D, 8mA, programmable level C17 C18 C19 C20 Parking brake position sensor signal PTO switch Power take-off neutral position switch Cross-axle differential lock switch C21 Frequency input (Engine speed signal) IN_FREQ_01 C22 Frequency input (Vehicle speed signal) IN_VSYSA_Speed C23 Not Used C24 Not Used C25 Not Used C26 Not Used W.H.D, 8mA, programmable level 120 , connected to MCAN L C27 MCAN_H Not Used C28 MCAN_L Not Used C29 MCAN_GND Not Used «Ground» IN_DIG_24 D, 1mA, programmable level IN_DIG_25 D, 1mA, programmable level IN_DIG_26 D, 8mA, programmable level IN_DIG_27 D, 1mA, programmable level IN_DIG_28 D, 8mA, programmable level C30 C31 C32 C33 C34 Center differential lock switch All-wheel drive system switch Unlocking the warning signal in the cab Engine Damage Warning Signal Engine brake switch / signal C35 High and low gear sensor IN_DIG_29 D, 8mA, programmable level C36 Menu button rotation to the right / scroll switch down IN_DIG_30 D, 8mA, programmable level C37 Sensor supply line OUT_SENSOR_PWR_01 Макс 10 мА C38 Sensor supply line OUT_SENSOR_PWR_02 Макс 10 мА C39 Not Used C40 Not Used OUT_33 D,PWM,L,1A OUT_33_DIAG C41 Not Used OUT 34 D,L,1A OUT_34_DIAG C42 GND circuit of connection “mass” «Ground» C43 Connecting “Ground” «Ground» C44 Connecting “Ground” «Ground» C45 Not Used - 20 Howo A7 Electrical equipment C46 Power take-off neutral solenoid valve OUT_12 G4,D,H,1A OUT_12_DIAG C47 Not Used C48 Relay for right side trailer light C49 Not Used C50 Main rear fog lamp C51 Not Used C52 Main reversing light OUT_13 G4,D,H,0.2A OUT_13_DIAG OUT_14 G4,D,H,1.8A,C OUT_14_DIAG OUT_14_SENSE OUT_15 OUT_15_DIAG G4,D,H,1.8A,C OUT_15_SENSE Table - Рrameter D № CBCU SIGNALS PLC USED CONTACT NAMES W, H.D, 8мА, programmable level D01 Position II of the light switch D02 ”Ground” sensor «Ground» D03 ”Ground” sensor «Ground» D04 ”Ground” sensor «Ground» D05 Differential lock signal D06 D07 Front fog lamp switch Rear fog lamp switch IN_DIG_31 PARAMETERS IN_DIG_32 D, 8мА, programmable level IN_DIG_33 D, 8mA, programmable level IN_DIG_34 D, 8mA, programmable level D08 ASR signal IN_DIG_35 D, 8mA, programmable level D09 Gearbox neutral position sensor (Neutral switch) IN_DIG_36 D, 8mA, programmable level D10 ICAN_GND D11 D12 D13 Analog input (air pressure sensor 1) Analog input (air pressure sensor 2) Analog input (fuel level sensor in the tank) «Ground» IN_ANA_01 Resistance sensor IN_ANA_02 Resistance sensor IN_ANA_03 Resistance sensor D14 Analog Input - Generator D + Terminal IN_ANA_04 Voltage sensor D15 Analog input (coolant temperature sensor) IN_ANA_05 Resistance sensor IN_ANA_06 Resistance sensor D16 Analog input (oil pressure sensor) D17 ICAN_H - D18 ICAN_H - D19 ICAN_L - D20 ICAN_L - D21 ”Ground” sensor D22 Alarm switch IN_DIG_37 D23 Light switch position (parking light switch) IN_DIG_38 «Ground» W.H.D, 8mA, programmable level W.H.D, 8mA, programmable level 22 21 Howo A7 Electrical equipment D24 Combined switch for intermittent operation of the windshield wiper IN_DIG_39 D.8мА с programmable level D25 Combined switch for low-speed operation of the windshield wiper IN_DIG_40 D.8мА с programmable level IN_DIG_41 D.8мА с programmable level D26 Combined wiper washer control switch D27 Signal to return the wiper blades to their original position IN_DIG_42 D.1мА с programmable level D28 Wheel axle lift confirmation signal IN_DIG_43 D.1мА с programmable level IN_DIG_44 D.1мА programmable level D29 Power take-off activation confirmation signal D30 ICAN_GND D31 Power supply of sensors with voltage + 5V OUT_ANA_PWR Макс 20мА / U D32 Horn button IN DIG 45 D.1мА с programmable level IN_DIG_46 D.8мА с programmable level IN_DIG_47 D.8мА с programmable level IN_DIG_48 D.8мА с programmable level D33 D34 D35 D36 D37 «Ground» All-wheel drive system activation confirmation signal Inter-wheel differential lock confirmation signal Low oil pressure warning signal (EGR engine) Water in fuel warning signal (diesel engine with battery power supply system) ADR signal (vehicles with ADR system) IN_DIG_49 Air filter clogged warning signal IN_DIG_50 W.H.D, 1mA, programmable level D.8мА с programmable level D38 Not Used - D39 Not Used - Not Used - table6 - Prameter Е № E01 E02 CBCU SIGNALS Connecting “Ground” (Kl.31) G3 Power Supply (PWR G3) PLC USED CONTACT NAMES «Ground» PWR_03 OUT_21 E03 Not Used PARAMETERS G3,D,H,3.6A,C OUT_21_DIAG OUT_21_SENSE The main lamp of the indicator of the right turn of the car OUT_16 G4,D,H,1.8A E04 OUT_16_DIAG (OptionSENSE) E05 The main lamp of the indicator of the left turn of the car OUT_17 G4,D,H,1.8A,C OUT_17_DIAG (OptionSENSE) The main lamp of a brake light of the car OUT_20 G3,D,H,1.8A,C E06 OUT_20_DIAG OUT_20_SENSE OUT_18 G4,D,PWM,H,2.6A.C E07 Rocker switch for lighting (modulated pulse width signal) OUT_18_DIAG (OptionSENSE) E08 Power supply G4 (PWR G4) PWR_04 E09 dipped headlights OUT_19 G3,D,H,10A,C OUT_19_DIAG OptionSENSE 22 Howo A7 Electrical equipment Table - Рrameter F № F01 F02 F03 F04 F05 CBCU SIGNALS Trailer Right Indicator Indicator Indicator of the front and rear main lights of the right direction indicator of the car Rear fog lamp for trailer Trailer brake light Ignition switch ON position (KL15) F06 Power supply G2 (PWR G2) F07 The main front and rear lights of the left turn indicator of the car F08 High beam relay F09 Connecting “Ground” (Kl.31) Washer pump motor F10 F11 Trailer reversing light F12 Power supply G1 (PWR G1) F13 Four-wheel drive / axle lift solenoid valve F14 Air conditioner relay PLC USED CONTACT NAMES PARAMETERS OUT_24 OUT_24_DIAG OUT_23 OUT_23_DIAG OUT_23_SENSE OUT_22 OUT_22_DIAG OUT_25 OUT_25_DIAG G2,D,H,5.6A,C OptionSENSE G2,D,H,1.8A,C IN_IGNITION W,H,1.6мА G2,D,H,3.6A,C OptionSENSE G2,D,H,3.6A,C OptionSENSE PWR_02 OUT_27 OUT_27_DIAG OUT_27_SENSE OUT_26 OUT_26_DIAG OUT_29 OUT_29_DIAG OUT_28 OUT_28_DIAG OUT_28_SENSE G1,D,H,1.8A,C G1,D,H,1.0A,C (OptionSENSE) «Ground» G1,D,H,1.8A,C (OptionSENSE) G1,D,H,1.8A,C PWR_01 OUT_30 G1,D,H,1.0A OUT_30_DIAG OUT_31 G1,D,H,1.0A OUT_31_DIAG VII Description of the functions of the contacts on the connectors of the instrument cluster The instrument cluster can have one connector, as shown in the figure below Figure - 81 Diagram of an arrangement of connectors of a combination of devices A description of the function of the contacts is given in the table below: 23 Howo A7 Electrical equipment Table - Description of the functions of contacts on the instrument cluster connector Female pin number on connector Appointment Female pin number on connector Appointment KL30 KL15 KL31 Not Used K-line Not Used I-CAN-H I-CAN-H I-CAN-L 10 I-CAN-L 11 Shielded wire I - CAN 12 Not Used 14 Not Used 13 Not Used Note: Some pins may not be used in a particular vehicle version VIII Troubleshooting Critical failures In the event of a significant system malfunction, an alarm will be activated on the LCD display of the instrument cluster “STOP” jam When the engine is running, a warning sound will work Among the significant are the following malfunctions: (1) Break in the circuit of the 1st air pressure sensor in the brake system drive (sensor resistance 240 ); (2) Break in the circuit of the 2nd air pressure sensor in the brake system drive (sensor resistance 240 ); (3) Short circuit in the circuit of the 1st air pressure sensor in the brake system drive (sensor resistance ); (4) Short circuit in the circuit of the 2nd air pressure sensor in the brake system drive (sensor resistance ); (5) Low air pressure in the 1st circuit of the brake system (short circuit for “mass” in the contact circuit B15 of the CBCU unit); (6) Low air pressure in the 2nd circuit of the braking system (short circuit on the “mass” in the contact circuit B16 of the CBCU unit); (7) Low air pressure in the additional circuit of the braking system (short circuit for “mass” in the contact circuit B17 of the CBCU unit); (8) Damage to the oil pressure sensor in the engine (sensor resistance ); (9) Low engine lubrication pressure (oil pressure 2600 rpm) Note: If these faults occur, you should stop the vehicle immediately and not resume driving until these faults are resolved! Failure to so may result in inadvertent or damage to the vehicle’s systems! Significant malfunctions If there are significant malfunctions on the LCD display, the corresponding alarm device will turn on (when operatingIf at least one of the malfunctions listed below under the numbers 1-9 appears, the buzzer will produce a series of 10 sound pulses following a period of 1c) After all faults are resolved, the buzzer and alarm on the LCD display will turn off The warning page on the screen will disappear and the normal normal operation page will appear Among the significant are the following malfunctions: (1) Low fuel level in the tank; (2) Break in the circuit of the fuel level sensor in the tank (resistance in the circuit of the specified sensor >240 ); (3) Short circuit in the circuit of the fuel level sensor in the tank; (4) Engine coolant temperature is too high (temperature exceeds 95°C); (5) Break in the circuit of the engine coolant temperature sensor (the resistance in the circuit of the specified sensor exceeds 50 K ); (6) Turn on the battery charging indicator (the voltage at the D+ terminal is less than 24V); 24 Howo A7 Electrical equipment (7) Increased voltage of the on-board network (more than 30V); (8) Too low voltage of the on-board network (less than 19V); (9) Warning of excessive clogging of the air filter; (10) Damage in the G1 power supply circuit of the CBCU; (11) Damage in the G2 power circuit of the CBCU; (12) Damage in the G3 power supply circuit of the CBCU; (13) Damage in the G4 power supply circuit of the CBCU; (14) Damage in the G5 power circuit of the CBCU; (15) Damage in the G6 power supply circuit of the CBCU; (16) Damage to the main brake light of the car; (17) Damage to the trailer brake light; (18) Damage to the front and rear lights of the vehicle’s left turn indicator; (19) Damage to the main lamp of the left turn indicator lamp of the vehicle; (20) Damage to the left turn lamp of the trailer; (21) Damage to the front and rear lights of the vehicle’s right-turn indicator lights; (22) Damage to the main lamp of the right turn indicator lamp of the vehicle; (23) Damage to the right turn indicator of the trailer; (24) Damage to the front fog lamps; (25) Damage to the rear fog lamp; (26) Damage to the fog lamp of the trailer coupling device; (27) Damage to the high beam of the headlamps; (28) Damage to the dipped-beam headlamp circuit; (29) Damage to the reversing lamp; (30) Damage to the trailer’s reversing lamp; (31) Damage to the main left parking lamp of the car; (32) Damage to the main right-hand clearance lamp of the car; (33) Damage to the additional lamp; (34) Damage to the electric motor of the washer pump; (35) Damage to the solenoid valve of the inter-wheel differential lock; (36) Damage to the solenoid valve of the center differential lock; (37) Damage to the solenoid valve of the all-wheel drive; (38) Damage to the solenoid valve of the power take-off device; (39) Damage to the solenoid valve for switching on the neutral position of the power take-off device; (40) The driver’s door is not closed; (41) Disruption of communication with the ABS system; (42) Communication with the tachograph (VDO supplies a tachograph that connects to the CAN bus); (43) Short circuit on the “mass” in the circuit of the air conditioner relay System Error Messages and Diagnostic Methods If there is a malfunction, first check the information on the instrument cluster display and then perform Diagnostic procedure according to the recommendations in the table below Table - VDO System Malfunction Reports and Possible Causes Place Designation of input circuits and their locations, descriptions of output circuits Screen display 25 Possible cause of the malfunction Howo A7 Electrical equipment When a malfunction occurs 1st circuit of the brake system 2nd circuit of the brake system Additional pneumatic system Engine coolant temperature Oil pressure Badge IN_AN_01 (D11), IN_ DIG_07 (B15) Air pressure gauge / low air pressure indicator in the brake system IN_AN_02 (D12), IN_ DIG_08 (B16) Air pressure gauge / low air pressure indicator in the brake system IN_DIG_09 (B17) Low air pressure alarm IN_AN_05 (D15) / PCAN, Coolant temperature indicator / coolant temperature indicator IN_AN_06 (D16) / PCAN, oil pressure sensor / low oil pressure alarm Exceeding the permissible engine speed Brake circuit pressure low The air pressure in the receiver is less than 5.5 x 0.1 MPa Brake circuit pressure low Auxiliary air pressure low Engine water temperature high If the coolant temperature rises above 950C while the engine is running, check the cooling system Engine oil pressure low With the engine running, the oil pressure in the main line does not reach a value of 0.6 x 0.1 MPa Engine over speed Within s, the crankshaft rotation speed exceeded 2600 rpm Fuel level in the tank IN_AN_03 (D13), fuel level indicator in the tank Fuel level low The amount of fuel in the tank does not exceed 1/8 of the full tank capacity Oil filter IN_DIG_03 (B10), Oil filter clogged Clogged oil filter, replace oil filter IN_DIG_14 (C08), Fuel filter clogged Fuel filter clogged, replace fuel filter IN_DIG_50 (D37), Air filter clogged Air filter clogged, replace air filter Accumulator battery, generator IN_AN_04(D14), After starting the engine, the voltage on the D + terminal does not exceed 24V Generator charging failure Possible cause: damage to the generator, violation in the wiring harness Cabin IN_DIG_26 (C32), Cab not locked The cab door is not locked IN_DIG_05 (B13), Cab door not locked Air pressure sensor in circuit of the brake system IN_AN_01 (D11), Air pressure meter The resistance value of the sensor installed in circuit of the Brake circuit air brake system is out of the specified range (open sensor) or pressure sensor damage in the circuit Check the resistance of the sensor and the corresponding wire line malfunction Air pressure sensor in circuit of the brake system IN_AN_02 (D12), Измеритель давления воздуха Clogged fuel filter Air filter The cab is not fixed Cause: Damage to the interlock device or wiring harness When the vehicle is moving, the cab door is not locked The resistance value of the sensor installed in circuit of the Brake circuit2air brake system is outside the specified range (open sensor) or pressure sensor damage in the circuit Check the resistance of the sensor and the corresponding wire line malfunction 26 Howo A7 Electrical equipment Engine coolant temperature sensor IN_AN_05 (D15), temperature indicator Engine water temperature sensor malfunction The resistance value of the sensor installed on the engine is outside the specified range (open sensor) or damage in the circuit Check the resistance of the sensor and the corresponding wire line The resistance value of the sensor installed on the engine is outside the specified range (open sensor) or damage in the circuit Check the resistance of the sensor and the corresponding wire line The resistance value of the sensor installed on the fuel tank is outside the specified range (open sensor) or damage in the circuit Check the resistance of the sensor and the corresponding wire line This error message appears when there is a communication failure between the engine management system and the central control unit Check CAN wires and ECM Fuel pressure sensor IN_AN_06 (D16), Fuel pressure indicator on LCD display Engine oil pressure sensor malfunction Fuel level sensor IN_AN_03 (D13), fuel level sensor malfunction Lost Communication With Engine Control System Communication bus of the engine management system Engine communication malfunction Lost Communication With ABS Communication bus with the ABS system ABS communication malfunction; This error message appears when the communication between the ABS system and the central control unit is interrupted Check the wires of the CAN communication line and the ABS control unit ICAN bus Traveling recorder communication malfunction This error message appears when the communication between the tachograph and the central control unit is broken Check CAN wiring and tachograph Tachograph Vehicle electrical system voltage IN_MAIN_IN_MPW R (in PLC program) IN_MAIN_IN_MPW R (in PLC program) Violation of voltage level in circuits of devices of group PWR_06(A02) Primary vehicle voltage high Primary vehicle voltage low The voltage level in the on-board network of the car exceeds 31.5V, which is higher than the value admissible for the electrical components of the car and can lead to its damage Check alternator, charging circuit and battery The voltage level in the vehicle’s on-board network is less than 20V, which can cause disruption of a number of system functions or lead to damage to electrical components Check alternator, charging circuit and battery The voltage level in the circuits of the group devices is less than the voltage of the on-board network Check the wiring harness, fuse and other elements connected between the power supply and pin of connector of the central control unit of the body equipment (a total of pins per CBCU power supply G6 power connector) failure Note: If a malfunction occurs, the supply voltage in the electrical circuits of this group may change, which may be accompanied by a violation of the functions of the devices connected to them Violation of the voltage level in the circuits of the devices of group The voltage level in the circuits of the group devices is less than the voltage of the on-board network Check the wiring harness, fuse and other elements connected between the power supply and pin of connector of the PWR_05(A08) CBCU power central control unit of the body equipment (a total of pins per supply G5 power connector) failure Note: If a malfunction occurs, the supply voltage in the electrical circuits of this group may change, which may be accompanied by a violation of the functions of the devices connected to them 27 Howo A7 Electrical equipment Violation of the voltage level in the circuits of the devices of group Violation of the voltage level in the circuits of the devices of group Violation of the voltage level in the circuits of the devices of group Violation of the voltage level in the circuits of the devices of group Electric motor on-sosa washer PWR_04(E08) PWR_03(E02) PWR_02(F06) PWR_01(F10) IN_DIG_41(D26) OUT_29(F10) The voltage level in the circuits of the group devices is less than the voltage of the on-board network Check the wiring harness, fuse and other elements connected between the power supply and pin of connector of the central control unit of the body equipment (a total of pins G4 power failure per connector) If the menu button is damaged, press it to replace the Menu knob failure function of rotating the button to the right Note: If a malfunction occurs, the supply voltage in the electrical circuits of this group may change, which may be accompanied by a violation of the functions of the devices connected to them The voltage level in the circuits of group devices is less than the voltage of the on-board network Check the wiring harness, fuse and other elements connected between the power supply and pin of the connector of the CBCU power supply, central control unit of the body equipment (a total of contacts per connector) G3 power failure Note: If a malfunction occurs, the supply voltage in the electrical circuits of this group may change, which may be accompanied by a violation of the functions of the devices connected to them The voltage level in the circuits of the devices of group is less than the voltage of the on-board network Check the wiring harness, fuse and other elements connected between the power supply and pin of the connector of the CBCU POWER SUP- central control unit of the body equipment (a total of 15 PLY G2 Power failure pins per connector) Note: If a malfunction occurs, the supply voltage in the electrical circuits of this group may change, which may be accompanied by a violation of the functions of the devices connected to them The voltage level in the circuits of group devices is less than the voltage of the on-board network Check the wiring harness, fuse and other elements connected between the power supply and pin 10 of connector of the CBCU power supply, central control unit of the body equipment (a total of 15 pins per connector) G1 power failure Note: If a malfunction occurs, the supply voltage in the electrical circuits of this group may change, which may be accompanied by a violation of the functions of the devices connected to them A short circuit on the “mass” in the circuit between the control Washer motor failure unit of the body equipment and the electric motor on the washer Check the specified circuit Primary vehicle stop lamp short circuit to the ground The main lamp of a stoplight of a car Input: Bus of the engine management system OUT_20 (E06) Overload in the chain of the main brake light of the car Primary vehicle stop lamp open circuit 28 If, after pressing the brake pedal, the brake lamp does not turn on and the specified fault message appears, this indicates that there is a short circuit in the circuit Check the wiring harness connected to the specified lamp If, after pressing the brake pedal, the brake light comes on and the above message appears, this means that an excessive power lamp is installed in the brake light (recommended power range 30 - 54W) Check the lamp and its wattage to ensure the specified amperage in the circuit If, after pressing the brake pedal, the specified message appears, this means that there is an open circuit in the brake light circuit or that a lamp of too low power is installed Check the lamp, its wattage and the condition of the wiring, and that the wiring harness is connected correctly Howo A7 Electrical equipment trailer stop lamp short circuit to the ground Trailer brake light Input: Bus of engine management system OUT_25 (F04) If on a car with a trailer, after pressing the brake pedal, the brake light comes on and the indicated message appears, this means that an excessive power lamp is installed in the brake light trailer stop lamp over (recommended power range 30 - 54W) load Check lamp and lamp wattage to ensure specified circuit amperage trailer stop lamp open circuit Primary vehicle left front/left rear direction signal lamp short circuit to the ground Front and rear main lamps of the left turn indicator of the car IN_DIG_16(C10) IN_DIG_37(D22); OUT_27(F07) If, on a vehicle with a trailer, after pressing the brake pedal, the brake light does not turn on and the indicated malfunction message appears, this indicates a short circuit in the circuit Check the harness connected to the indicated lamp If the above message appears on a vehicle with a trailer after pressing the brake pedal, this means that there is an open circuit in the brake light circuit or that a lamp of too low power is installed Check the lamp, its wattage and the condition of the wiring, and that the wiring harness is connected correctly If the indicated message appears on the LCD display when the left turn indicator light switch or the hazard warning light switch is turned on, this indicates a short circuit in the circuit Check the wiring harness and lamp If the indicated message appears on the LCD display when the left turn indicator light switch or the hazard warning light switch is turned on, this means that excessive power Primary vehicle lamps are installed in the direction indicator lights left front/left rear direction signal lamp (recommended power range 30 - 54W) Make sure that the wattage of the installed lamps overload corresponds to the recommended value of the instruction Primary vehicle Left front and left rear direction indicator lamp open circuit If, when you turn on the left turn indicator light switch or the hazard warning light switch, these lights turn on, but the indicated error message appears on the LCD display, this means that lamps of too low power are installed in the turn signal lights (recommended power range 30 54W) Make sure that the wattage of the lamps used and the condition of the wiring harness connected to them meet the requirements If the indicated message appears on the LCD display when the Primary vehicle left left turn indicator light switch or the hazard warning light middle direction sigswitch is turned on, this indicates a short circuit in the nal lamp short circuit circuit Check the wiring harness and lamp to the ground The main middle light of the left turn indicator of the car IN_DIG_16(C10); IN_DIG_37(D22); OUT_17(E05) Primary vehicle left middle direction signal lamp overload If, when the left turn indicator switch or the hazard warning light switch is turned on, the specified lamp turns on, but the indicated error message appears on the LCD display, this means that an excessive power lamp is installed in the direction indicator lamp (recommended power range 15 - 27W) Make sure that the wattage of the installed lamps corresponds to the recommended value of the instruction Primary vehicle left middle direction signal lamp open circuit If, when the left turn indicator light switch or the hazard warning light switch is turned on, these lights turn on, but the indicated error message appears on the LCD display, this means that lamps of too low power are installed in the turn signal lights (recommended power range 15 - 27W) Check the lamp, its wattage and the condition of the wiring, and that the wiring harness is connected correctly 29 Howo A7 Electrical equipment If the indicated message appears on the LCD display when the Trailer left side left turn indicator light switch or the hazard warning light direction signal switch is turned on, this indicates a short circuit in the lamp short circuit to circuit Check the wiring harness and lamp the ground Trailer left direction indicator lamp Front rear main lights of the indicator of the right in-gate of the car IN_DIG_16(C10); IN_DIG_37(D22); OUT_32(F15) IN_DIG_15(C09); IN_DIG_37(D22); OUT_23(F02) Trailer left side direction signal lamp overload If, when the left turn indicator switch or hazard warning light switch is turned on, the specified lamp turns on, but the indicated error message appears on the LCD display, this means that an excessive power lamp is installed in the direction indicator lamp (recommended power range 15 - 180W) Make sure that the wattage of the installed lamps corresponds to the recommended value of the instruction If, when the left turn indicator light switch or the hazard warning light switch is turned on, the specified light turns on, but the indicated error message appears on Trailer left side the LCD display, this means that a lamp of too low direction signal power is installed in the turn signal light (recommended lamp open circuit power range 15 - 180W) Check the lamp, its wattage and the condition of the wiring, and that the wiring harness is connected correctly Primary vehicle If the indicated message appears on the LCD display when the right turn indicator light switch or the hazard warning light right front/right rear direction signal switch is turned on, this indicates a short circuit in the lamp short circuit to circuit Check the wiring harness and lamp the ground If, when you turn on the right turn indicator switch or the hazard warning light switch, these lights turn on, but the indicated error message appears on the LCD display, Primary vehicle this means that the direction indicator lights are equipped right front/ right rear direction signal with excessive power bulbs (recommended power range 30 - 54W) Make sure that the wattage of the installed lamp overload lamps corresponds to the recommended value of the instruction If, when you turn on the right turn indicator light switch or the hazard warning light switch, the specified lights turn on, but the indicated error message appears on the LCD Primary vehicle display, this means that lamps of too low power are right front/ right installed in the turn signal lights (recommended power rear direction signal range 30 - 54W) Make sure that the wattage of the lamp open circuit installed lamps matches the recommended value and that the wiring harness is in good condition If the indicated message appears on the LCD display when the Primary vehicle right right turn indicator light switch or the hazard warning light middle direction switch is turned on, this indicates a short circuit in the signal lamp short circuit Check the wiring harness and lamp circuit to the ground The main middle light of IN_DIG_15(C09); the indicator of the right IN_DIG_37(D22); turn of the car OUT_16(E04) Primary vehicle Right middle direction indicator lamp overload Primary vehicle Right middle direction indicator lamp open circuit 30 If, when you turn on the right turn indicator switch or the hazard warning light switch, the specified lights turn on, but the indicated error message appears on the LCD display, this means that excessive power lamps are installed in the direction indicator lights (recommended power range 15 - 27W) Make sure that the wattage of the installed lamps corresponds to the recommended value of the instruction If, when you turn on the right turn indicator light switch or the hazard warning light switch, the specified lights turn on, but the indicated error message appears on the LCD display, this means that lamps of too low power are installed in the turn signal lights (recommended power range 15 - 27W) Check the lamp, its wattage and the condition of the wiring, and that the wiring harness is connected correctly Howo A7 Electrical equipment Trailer right side direction signal lamp short circuit to the ground Trailer right turn signal lamp IN_DIG_16(C09); IN_DIG_37(D22); OUT_24(F01) trailer Right side direction indicator lamp overload If, when you turn on the right turn indicator switch or the hazard warning light switch, the specified lamp turns on, but the indicated error message appears on the LCD display, this means that an excessive power lamp is installed in the direction indicator lamp (recommended power range 15 - 180W) Make sure that the wattage of the installed lamps corresponds to the recommended value of the instruction trailer Right side direction indicator lamp open circuit If, when you turn on the right turn indicator light switch or the hazard warning light switch, the specified light turns on, but the indicated error message appears on the LCD display, this means that a lamp of too low power is installed in the turn signal light (recommended power range 15 - 180W) Check the lamp, its wattage and the condition of the wiring, and that the wiring harness is connected correctly Primary vehicle Rear fog lamp short circuit to the ground Car main rear fog light IN_DIG_34(D07); OUT_14(C50) If, after turning on the side lights and pressing the front and rear fog light switch, the indicated malfunction message appears, this means that there is an open circuit in the main rear fog light circuit or a lamp of too low power is installed Check the lamp, its wattage and the condition of the wiring, and that the wiring harness is connected correctly If after turning on the side light and pressing on the front fog lamp switch, they not turn on, and the specified message appears about a malfunction, this indicates the presence of a short circuit in the circuit Check the harness connected to the indicated lamp If, after turning on the side lights and pressing the fog lamp switch, they not turn on, and at the same time the indicated malfunction message Primary vehicle appears, this means that lamps of too high power are installed in Front fog lamp the main fog lights of the car (recommended power range 98 overload 182 W) Check lamp and lamp wattage to ensure specified circuit amperage If, after turning on the side lights and pressing the front fog lamp switch, the indicated malfunction appears, this means that there is an open circuit in the car’s main fog lamp circuit or lamps Primary vehicle Front fog lamp open of too low power are installed Check the lamp, its wattage and the condition of the wiring, and that the circuit wiring harness is connected correctly Primary vehicle Front fog lamp short circuit to the ground IN_DIG_33(D06); OUT_03(A07) If after turning on the side light and pressing the front and rear fog light switch, the fog lamps and lamps not turn on, and the specified message appears about a malfunction, this indicates the presence of a short circuit in the circuit Check the harness connected to the indicated lamp If after turning on the side light and pressing on the front and rear fog light switch, the lamp of the main rear fog lamp turns on, however, the indicated malfunction message appears, this means that in the main day the fog lamp is installed Primary vehicle rear a lamp of too high power (recommended power range 30 - 54 fog lamp overload W) Check lamp and lamp wattage to ensure specified circuit amperage Primary vehicle rear fog lamp open circuit Main anti-fog headlights of the car If the indicated message appears on the LCD display when the right turn indicator light switch or the hazard warning light switch is turned on, this indicates a short circuit in the circuit Check the wiring harness and lamp 31 Howo A7 Electrical equipment If, after turning on the side light and pressing the switch for the front and rear fog lights, the fog trailer rear lamps and lamps not turn on, and the indicated fog lamp error message appears, this indicates a short circuit short circuit in the circuit to the Check the harness connected to the specified lamp ground Rear fog lamp of the trailer IN_DIG_34(D07); OUT_22(F03) trailer rear fog lamp overload trailer rear fog lamp open circuit High beam headlights IN_DIG_13(C07); OUT_26(F08) If, after turning on the side light and pressing the front and rear fog light switch, the lamp of the main rear fog lamp turns on, but the indicated malfunction message appears, this means that the lamp in the main rear fog lamp is set to a lamp of too high power (recommended power range 30 54W) Check the lamp and its wattage to ensure the specified amperage in the circuit If after turning on the side light and pressing the front and rear fog lamp switch, the indicated malfunction message appears, this means that there is an open circuit in the main rear fog lamp circuit or a lamp of too low power is installed Check the lamp, its wattage and the condition of the wiring, and the correct connection of the wiring harness If, after turning on the high-beam switch, the High beam indicated message appears, this means that the relay short circuits of the central control unit and the relay have circuit to the a short circuit to ground Check harness and relay ground If, after setting the lighting switch to position II and turning on the dipped beam switch, the dipped Dipped beam headlamps not turn on, and the specified beam short message appears, this means that there is a short circuit to the circuit to ground in the specified circuit Check ground bulbs and attached wiring harness dipped headlights IN_DIG_12 (C06); OUT_19(E09) Dipped beam overload Dipped beam open circuit 32 If, after the light switch is set to position II and the passing beam is switched on, the passing lamps are switched on, but the indicated fault message appears, this means that the power consumed by the lamps exceeds the set value (126-234 W) Check the lamp and its power to provide a given amount of current in the circuit If, after setting the illumination switch to position II and turning on the passing beam switch, the specified malfunction message appears, this means that the power consumed by the lamps is lower than the specified value Check the lamp, its power and the condition of the electrical wiring, as well as the correct connection of the wiring harness Howo A7 Electrical equipment If, after turning on the ignition and setting the transmission control lever to the reverse position, Primary the main reverse light of the car does not turn on, vehicle but the indicated error message appears, this means reversing that there is a short circuit to ground in the circuit of lamp short this component Check bulbs and attached wiring circuit to the harness ground Main reversing light IN_DIG_17(C11); OUT_15(C52) Primary vehicle reversing lamp overload Primary vehicle reversing lamp open circuit If, after turning on the ignition and setting the transmission control lever to the reverse position, the main reversing lamp of the car comes on, but the indicated malfunction message appears, this means that the lamp in the indicated lamp is installed too high power (recommended power range 30 - 54W) Check the lamp and its wattage to ensure the specified amperage in the circuit If, after turning on the ignition and setting the transmission control lever to the reverse position, the indicated error message appears, this means that the power consumed in the specified lamp circuit is outside the specified range Check the lamp, its wattage and the condition of the wiring, and the correct connection of the wiring harness If, after turning on the ignition and moving the transmission control lever to the reverse position, if trailer the trailer reverse light does not come on, but the reversing indicated error message appears, this means that this lamp short component has a short to ground circuit to the Check bulbs and attached wiring harness ground Trailer reversing light IN_DIG_17(C11); OUT_28 (F11) trailer reversing lamp overload trailer lamp open circuit 33 If, after turning on the ignition and setting the transmission control lever to the reverse position, the trailer reversing light comes on, but the indicated malfunction message appears, this means that a lamp of too high power is installed in the specified lamp (recommended power range 30 54W) Check the lamp and its wattage to ensure the specified amperage in the circuit If, on a car with a trailer, after turning on the ignition and setting the gearbox control lever to the reverse position, the indicated error message appears, this means that the power consumed in the circuit of the specified lamp is out of the specified range Check the lamp, its wattage and the condition of the wiring, and the correct connection of the wiring harness Howo A7 Electrical equipment Additional lantern IN_DIG_38(D23); OUT_18(E07) If, after turning on the ignition and turning on the side light, the auxiliary lamp does not turn on and the indicated malfunction message appears, this Switch lamp means that there is a short circuit to ground in the short circuit indicated circuit to the ground Check the lamp and attached wiring harness If, after turning on the ignition and turning on the side lighting, the left main marker light of the vehicle, as well as the side marker lamps, the Primary upper lamp, marker lamps and the license plate vehicle left lamp not turn on even when side position This displays the indicated Fault message, which lamp short means that the indicated circuit has a short to circuit to the ground Check the lamp and attached wiring ground harness Left main side light of the vehicle IN_DIG_38(D23); OUT_06(A06) If, after turning on the ignition and turning on the side lighting, the left main marker light of the vehicle, as well as the side marker lights, the upper light, side lights come on, but the indicated error Primary message appears, this means that vehicle left the power consumed in the specified circuit side position exceeds the specified value (the specified power lamp range is 35-74W) Check lamp and lamp wattage overload to ensure specified circuit amperage If, after turning on the ignition and side light, the indicated malfunction message appears, this means Primary that the power consumed in the lamp circuit of the vehicle left specified lamp is out of the specified range Check side position the lamp, its wattage and the condition of the lamp open wiring, and that the wiring harness is connected circuit correctly 34 ... description of the power circuits on the HOWO7 C car, which allows you to diagnose all their possible malfunctions Howo A7 Electrical equipment Figure 6-79 HOWO7 C Vehicle Power Supply Circuit Diagram.. .Howo A7 Electrical equipment A8 Starter power supply S4 G1.G2 Accumulator battery K28 Mechanical type... of the right control unit 3) In this case, the power contacts of the start relay A8 are closed Howo A7 Electrical equipment e Terminal 50 of starter M1 is supplied with voltage, the starter starts