chap43 pps Automotive technology at University of Cambridge

start Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 43, the reader should be able to: • • • Prepare for ASE Electrical/Electronic Systems (A6) certification test content area “F” (Gauges, Warning Devices, and Driver Information System Diagnosis and Repair) Be able to identify the meaning of dash warning symbols Discuss how a fuel gauge works Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 43, the reader should be able to: • • • Explain how to use a service manual to troubleshoot a malfunctioning dash instrument Describe how a navigation system works List the various types of dash instrument displays Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: analog backup camera • bulb test cathode fluorescent lighting (CFL) • cathode ray tube (CRT) • combination valve electromagnetic • electronically erasable programmable read-only memory (EEPROM) global positioning system (GPS) • head-up display (HUD) instrument panel (IP) Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: lane departure warning system (LDWS) • light-emitting diode (LED) • liquid crystal display (LCD) nonvolatile random-access memory (NVRAM) permanent-magnet (PM) generator • phosphor • pressure differential switch rear park assist (RPA) • stepper motor telltale lamp • thermoelectric vacuum tube fluorescent (VTF) display • WOW display Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 DASH WARNING SYMBOLS All vehicles are equipped with warning lights that are often  confusing to drivers Because many vehicles are sold throughout the world, symbols  instead of words are being used as warning lights See Figure 43–1 for examples and meanings of most symbols.  Always check service information for the exact meaning on the  vehicle being serviced Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 43–1 (a) Typical dash warning symbols and their meanings Due to differences in  computer displays, the  colors in this image  may not exactly match  federally mandated  colors Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 43–1 (b) Typical dash warning symbols and their meanings (cont) Due to differences in  computer displays, the  colors in this image  may not exactly match  federally mandated  colors See the complete chart on  Page 477 of your textbook.  Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 ANALOG DASH INSTRUMENTS Electromagnetic dash instruments use small electromagnetic  coils that are connected to a sending unit for such things as fuel  level, water temperature, and oil pressure. The resistance of the  sensor varies with what is being measured See Figure 43–2 for typical electromagnetic fuel gauge operation Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 43–2 Electromagnetic fuel gauge wiring If the sensor wire is unplugged and grounded, the needle should point to “E” (empty) If the sensor wire is unplugged and held away from ground, the needle should point to “F” (full) Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 If the distance between the rear bumper and the object is less than  11 inches (28 cm), all indicator lamps flash and the chime will  sound continuously The ultrasonic sensors embedded in the rear bumper “fire”  individually every 150 ms (27 times per second).  Figure 43–36 The small round buttons in the rear bumper are ultrasonic sensors used to sense distance to an object Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 The sensors fire and then receive a return signal and arm to fire  again in sequence from the left sensor to the right sensor Each sensor has three wires: An 8­volt supply wire from the RPA module is used to power  the sensor A reference low or ground wire A signal line used to send and receive commands to and from  the RPA module Check For a Repainted Bumper The ultrasonic sensors embedded in the bumper are sensitive to paint thickness because the paint covers the sensors If the system does not seem to be responding to objects, and if the bumper has been repainted, measure the paint thickness using a nonferrous paint thickness gauge The maximum allowable paint thickness is mils (0.006 inch or 0.15 mm) Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Diagnosis The rear parking assist control module is capable of  detecting faults and storing diagnostic trouble codes (DTCs) If a fault has been detected by the control module, the red lamp  flashes and the system is disabled Follow service information diagnostic procedures because the rear  parking assist module cannot usually be accessed using a scan tool.  Most systems use the warning lights to indicate trouble codes Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 LANE DEPARTURE WARNING SYSTEM Parts and Operation  The lane departure warning system  (LDWS) uses cameras to detect if the vehicle is crossing over lane  marking lines on the pavement. Some systems use two cameras,  one mounted on each outside rearview mirror. Some systems use  infrared sensors located under the front bumper to monitor the lane  markings on the road surface If the cameras detect that the vehicle is starting to cross over a lane  dividing line, a warning chime will sound or a vibrating  mechanism mounted in the driver’s seat cushion is triggered on the  side where the departure is being detected This warning will not occur if the turn signal is on in the same  direction as detected Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Diagnosis and Service  Before attempting to service or repair a  lane departure warning system fault, check service information for  an explanation on how the system is supposed to work If the system is not working as designed, perform a visual  inspection of the sensors or cameras, checking for damage from  road debris or evidence of body damage, which could affect the  sensors After a visual inspection, follow the vehicle manufacturer’s  recommended diagnosis procedures to locate and repair the fault in the system Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 ELECTRONIC DASH INSTRUMENT DIAGNOSIS AND TROUBLESHOOTING If one or more electronic dash gauges do not work correctly, first check  the WOW display that lights all segments to full brilliance whenever the  ignition switch is first switched on If all segments of the display do not operate, then the entire electronic  cluster must be replaced in most cases If all segments operate during the WOW display but do not function  correctly afterwards, the problem is most often a defective sensor or  defective wiring to the sensor Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 All dash instruments except the voltmeter use a variable­resistance  unit as a sensor for the system being monitored. Most new­vehicle  dealers are required to purchase essential test equipment, including  a test unit that permits the technician to insert various fixed­ resistance values in the suspected circuit IF a 45­ohm resistance is put into the fuel gauge circuit that reads  from 0 to 90 ohms, a properly operating dash unit should indicate  one­half tank. The same tester can produce a fixed signal to test the  operation of the speedometer and tachometer Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 If this type of special test equipment is not available, the electronic  dash instruments can be tested using the following procedure: With the ignition switched off, unplug the wire(s) from the  sensor for the function being tested. For example, if the oil  pressure gauge is not functioning correctly, unplug the wire  connector at the oil pressure­sending unit With the sensor wire unplugged, turn the ignition switch on  and wait until the WOW display stops. The display for the  affected unit should show either fully lighted segments or no  lighted segments, depending on the make of the vehicle and  the type of sensor Turn the ignition switch off. Connect the sensor wire lead to  ground and turn the ignition switch on. After the WOW  display, the display should be the opposite (either fully on or  fully off) of the results in step 2 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Testing Results  If the electronic display does function fully on and  fully off with the sensor unplugged and then grounded, the problem  is a defective sensor If the display fails to function fully on and fully off when sensor  wire(s) are opened and grounded, the problem is usually in wiring  from sensor to electronic dash or it is a defective electronic cluster CAUTION: Whenever working on or near any type of electronic dash  display, always wear a wire attached to your wrist (wrist strap) connected  to a body ground to prevent damaging the electronics with static  electricity Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Keep Stock Overall Tire Diameter Whenever larger (or smaller) wheels or tires are installed, speedometer and odometer calibration are also thrown off This can be summarized as: • • Larger-diameter tires.The speed showing on the speedometer is slower than actual speed The odometer reading will show fewer miles than actual Smaller-diameter tires.The speed showing on the speedometer is faster than actual speed The odometer reading will show more miles than actual General Motors trucks can be recalibrated with a recalibration kit (1988– 1991), or a replacement controller assembly called a digital ratio adapter controller (DRAC) located under the dash It may be possible to recalibrate the speedometer and odometer on earlier models, before 1988, or vehicles that use speedometer cables by replacing the drive gear in the transmission Check service information for the vehicle being serviced Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 MAINTENANCE REMINDER LAMPS Maintenance reminder lamps indicate the oil should be changed or   other service is required. There are numerous ways to extinguish a  maintenance reminder lamp. Some require the use of a special tool To reset the oil service reminder light on many General Motors  vehicles: Step #1  Turn the ignition key on (engine off) Step #2  Depress the accelerator pedal three times and hold it down  on the fourth Step #3  When the reminder light flashes, release the accelerator  pedal Step #4  Turn the ignition key to the off position Step #5  Start the engine and the light should be off Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Fuel Gauge Diagnosis Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Fuel Gauge Diagnosis Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY Most digital and analog (needle­type) dash gauges use  variable resistance sensors Dash warning lamps are called telltale lamps Many electronically operated or computer­operated dash  indicators require that a service manual be used to perform  accurate diagnosis Permanent­magnet (PM) generators produce an AC signal and are used for vehicle speed and wheel speed sensors Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 end Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458