LEMON Manuals: Even more car manuals for everyone
Home >> Audi >> 1998 >> A4 Avant >> Repair and Diagnosis (Single Page) >> Electrical >> Gauges >> Instrument Panels >> System Testing >> Auto-Check System

Auto-Check System

NOTE: Before proceeding with these tests, ensure that battery is fully charged, fuses are not blown, voltage stabilizer is okay and Auto-Check system is coded properly.
  1. Connecting Test Equipment - Access back of instrument cluster. Remove Auto-Check system display. Connect all connectors except Blue 26-pin connector. See Figure. Connect Adapter Harness (VAG 1598/4) to Blue 26-pin harness connector and to back of instrument cluster. Connect adapter harness to Test Box (VAG 1598). After test equipment is hooked up, go to next step.
  2. Check Voltage Supply - Connect positive voltmeter lead to terminal No. 1 of circuit board connector T6g and negative lead to ground. See Figure. If battery voltage exists, go to next step. If battery voltage does not exist, check open in wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  3. Check System Ground - Connect positive voltmeter lead to terminal No. 1 of circuit board connector T6g and negative lead to terminal No. 3 of circuit board connector T5c. If battery voltage exists, go to next step. If battery voltage does not exist, check open in wiring. See, at end of article, WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  4. Check Ignition Voltage Supply - Connect positive voltmeter lead to terminal No. 4 of circuit board connector T5c and negative lead to terminal No. 3 of circuit board connector T5c. Turn ignition switch to RUN position. If battery voltage exists, turn ignition switch off and go to next step. If battery voltage does not exist, check open in wiring. See, at end of article, WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  5. Check Voltage Stabilizer Voltage Supply - Connect positive voltmeter lead to terminal No. 6 of circuit board connector T6g and negative lead to terminal No. 3 of circuit board connector T5c. Turn ignition switch to RUN position. If 9-11 volts exists, turn ignition switch off and go to next step. If 9-11 volts do not exist, check open in wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  6. Check Lighting Signal (Terminal 58) - Connect positive voltmeter lead to terminal No. 3 of circuit board connector T6g and negative lead to terminal No. 3 of circuit board connector T5c. Turn parking lights on. If battery voltage exists, turn parking lights off and go to next step. If battery voltage does not exist, check light switch. If light switch is okay, check open in wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  7. Check Lighting Signal (Terminal 58d) - Connect positive voltmeter lead to terminal No. 2 of circuit board connector T6g and negative lead to terminal No. 3 of circuit board connector T5c. Turn parking lights on. If 3-12 volts exists, turn parking lights off and go to next step. If 3-12 volts does not exist, check light and dimmer switches. If light and dimmer switches are okay, check open in wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  8. Check Fuel Level Sensor Signal - Connect positive ohmmeter lead to terminal No. 5 of circuit board connector T6g and negative lead to terminal No. 3 of circuit board connector T5c. If 30-300 ohms exists, go to next step. If 30-300 ohms does not exist, check fuel level sensor. If fuel level sensor is okay, check open in wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
    NOTE: Before proceeding, ensure charging system is functioning properly.
  9. Check Generator Voltage Supply (Ignition Off) - Connect positive voltmeter lead to terminal No. 5 of circuit board connector T5c and negative lead to terminal No. 3 of circuit board connector T5c. If no voltage exists, leave voltmeter connected and go to next step. If voltage exists, check wiring. See, at end of article, WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  10. Check Generator Voltage Supply (Engine Running) - Start engine. If 13.5-14.5 volts exists, go to next step. If 13.5-14.5 volts does not exist, check open in wiring. See, at end of article, WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
    NOTE: Before proceeding, ensure cooling system is functioning properly. Ensure coolant level switch and electronic thermoswitch are also functioning properly.
  11. Check Engine Coolant Level & Coolant Temperature Signals -Connect positive voltmeter lead to terminal No. 1 of circuit board connector T6g and negative lead to terminal No. 1 of circuit board connector T5c. Ensure coolant expansion tank is filled to MAX level and engine is within normal operating temperature. Ensure that all conditions listed in COOLANT SIGNALS TEST table are met. If all conditions are met, go to next step. If any condition is not met, check short to ground in wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
    COOLANT SIGNALS TEST

    Condition Voltage Reading
    Normal 0
    Bridged Coolant Level Harness Terminals (1) 12
    Disconnected Electronic Thermoswitch 0
    Grounded Electronic Thermoswitch Terminal "C" (2) 12
    (1) Disconnect coolant level switch harness connector and bridge terminals.
    (2) Disconnect electronic thermoswitch harness connector and ground terminal "C". See Figure.
  12. Vehicle Speed Sensor Signal - Connect LED test light between terminal No. 4 of circuit board connector T6g and terminal No. 4 of circuit board connector T5c. Turn ignition switch to RUN position. Push vehicle slowly in either direction. If LED flashes, turn ignition switch off and go to next step. If LED light does not flash, check vehicle speed sensor. If vehicle speed sensor is okay, check for open in wiring. See, at end of article, WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  13. Check Brake & Hydraulic Fluid Level Signals - Connect positive voltmeter lead to terminal No. 1 of circuit board connector T6g and negative lead to terminal No. 2 of circuit board connector T5c. Ensure that brake and hydraulic fluid reservoirs are filled to MAX level. Ensure that all the conditions listed in the BRAKE & HYDRAULIC SIGNALS TEST  are met. If all conditions are met, go to next step. If any condition is not met, check short to ground in wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
    BRAKE & HYDRAULIC SIGNALS TEST

    Condition Voltage Reading
    Normal 0
    Bridged Brake Fluid Level Harness Terminals (1) 12
    Disconnected Electronic Thermoswitch 0
    Bridged Hydraulic Fluid Level Harness Terminals (2) 12
    (1) Disconnect brake reservoir switch harness connector and bridge terminals.
    (2) Disconnect electronic thermoswitch harness connector and ground terminal "C". See Figure.
  14. Check Windshield Washer Level Signal - Connect positive voltmeter lead to terminal No. 1 of circuit board connector T6g and negative lead to terminal No. 16 of test box. Ensure windshield washer reservoir is filled to MAX level. Ensure that all conditions listed in WINDSHIELD WASHER LEVEL SIGNAL TEST  table are met. If all conditions are met, go to next step. If any condition is not met, check windshield washer level switch. See INDICATOR LIGHT  under COMPONENT TESTING. If windshield washer level sensor is okay, check short to ground in wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
    WINDSHIELD WASHER LEVEL SIGNAL TEST

    Condition Voltage Reading
    Normal 0
    Windshield Washer Pump Harness Disconnected 0
    Bridged Terminals No. 1 & 3 At Harness Connector (1) 12
    (1) Disconnect washer motor harness connector and bridge terminals No. 1 and 3. See Figure.
  15. Check .9, 1.8 Or 2.5 Bar Oil Pressure Switch Signal - Connect positive voltmeter lead to terminal No. 1 of circuit board connector T6g and negative lead to terminal No. 17 of test box. Ensure that all conditions listed in 2.5, 1.8 OR .9, 1.8 OR 2.5 BAR OIL PRESSURE SWITCH SIGNAL TEST table are met. If all conditions are met, go to next step. If any condition is not met, check .9, 1.8 or 2.5 bar oil pressure switch. See OIL PRESSURE SWITCHES  under COMPONENT TESTING. If oil pressure switch is okay, check the wiring. Refer to WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
    .9, 1.8 OR 2.5 BAR OIL PRESSURE SWITCH SIGNAL TEST

    Condition Voltage Reading
    Ignition Switch In RUN Position 0
    Engine Running At 2800 RPM 12
  16. Check Low Beam Signal - Disconnect Black harness connector from rear lamp control module. Connect positive voltmeter lead to terminal No. 18 at test box and negative lead to terminal No. 3 of circuit board connector T5c. Turn ignition switch to RUN position. Turn headlights on to low beam. If 1.5 volts or less exists, turn lights and ignition switch off and go to next step. If greater than 1.5 volts exists, check front lamp control module or bad bulb. If lamp control module and bulbs are okay, check wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  17. Check Taillight Signal - Connect Black harness connector to rear lamp control module. Connect positive voltmeter lead to terminal No. 18 at test box and negative lead to terminal No. 3 of circuit board connector T5c. Turn ignition switch to RUN position. Turn parking lights on. If 1.5 volts or less exists, turn lights and ignition switch off and go to next step. If greater than 1.5 volts exists, check for bad rear lamp control module or bad bulb. If lamp control module and bulbs are okay, check wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  18. Check .3 Bar Oil Pressure Switch Signal - Connect positive voltmeter lead to terminal No. 1 of circuit board connector T6g and negative lead to terminal No. 19 of test box. Ensure that all conditions listed in .3 BAR OIL PRESSURE SWITCH SIGNAL TEST TABLE table are met. If all conditions are met, go to next step. If any condition is not met, check .3 bar oil pressure switch. Refer to OIL PRESSURE SWITCHES  under COMPONENT TESTING. If oil pressure switch is okay, check wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
    .3 BAR OIL PRESSURE SWITCH SIGNAL TEST

    Condition Voltage Reading
    Ignition Switch In RUN Position 12
    Engine Running 0
  19. Check Radio Antenna Signal (Gamma Radio Only) - Turn engine off. Connect voltmeter negative lead to terminal No. 3 of circuit board connector T5c. Turn ignition switch to RUN position. Connect voltmeter positive lead to appropriate test box terminal and observe voltmeter reading. Ensure voltage is as specified in RADIO ANTENNA SIGNAL TEST  table. If all voltage readings are correct, turn radio and ignition off and go to next step. If any voltage reading is not correct, check radio. If radio is okay, check wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
    RADIO ANTENNA SIGNAL TEST

    Terminal No. Voltage Reading
    20 Approx. 0.1
    21 5
    22 5
  20. Check Engine Speed Sensor Signal - Connect Engine Tester (VW 1367) to power and ground in engine compartment. Connect Green wire from engine tester to terminal No. 23 of test box. Select RPM test range. Start engine. If engine RPM is displayed on tester, turn ignition switch off and go to next step. If engine RPM is not displayed on tester, check open in wiring. See WIRING DIAGRAMS . If wiring is okay, check for faulty Electronic Control Module (ECM). If ECM is okay, replace instrument cluster printed circuit board.
  21. Check Brake Light Signal (Pedal Depressed) - Connect positive voltmeter lead to terminal No. 25 at test box and negative lead to terminal No. 3 of circuit board connector T5c. Turn ignition switch to RUN position. Turn headlights on low beam. Depress brake pedal. If battery voltage exists, go to next step. If battery voltage does not exist, check rear lamp control module or bad bulb. If lamp control module and bulbs are okay, check wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
  22. Check Brake Light Signal (Pedal Released) - Release brake pedal. If 1.5 volts or less exists, replace Auto-Check control module. If greater than 1.5 volts exists, check rear lamp control module or bad bulb. If lamp control module and bulbs are okay, check wiring. See WIRING DIAGRAMS . If wiring is okay, replace instrument cluster printed circuit board.
scientia non olet · About LEMON Manuals