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Diagnosis & Testing

WARNING: Disable air bag system before working around steering column or removing any air bag system component. See AIR BAG RESTRAINT SYSTEM article.
  1. Check ENGINE and STOP fuses. If fuses are okay, go to next step. If either fuse is blown, correct the cause and replace.
  2. Turn ignition off. Unplug 6-pin and 10-pin connectors from interior fuse panel. Unplug connectors from Brake On/Off (BOO) switch and speed control module, located behind instrument panel, to left of steering column. Check Yellow/Red and Black/White wires at fuse panel connector for short to ground. If no short exists, go to next step. Repair wiring as necessary.
  3. Reconnect wiring to fuse panel. Turn ignition on. Measure voltage at Black/White wire at 6-pin speed control module connector. If voltage is greater than 10 volts, go to next step. If voltage is not greater than 10 volts, repair Black/White wire.
  4. Turn ignition off. Press brake pedal. If stoplights work, go to next step. If stoplights do not work, repair stoplight circuit.
  5. Press brake pedal. Measure voltage at White/Green wire (A/T) or Blue/Orange wire (M/T) at 6-pin connector. If voltage is greater than 10 volts, go to step 9) (A/T), or to step 8) (M/T). If voltage is not greater than 10 volts, repair White/Green wire (A/T), or go to next step (M/T).
  6. Unplug connectors from BOO switch and clutch position switch. Check Blue/Orange wire for continuity between clutch pedal switch and speed control module or short to ground. Go to next step if wire is okay. Repair Blue/Orange wire if it is open or shorted to ground.
  7. Check White/Green wire between clutch pedal switch and BOO switch for continuity or short to ground. Go to next step if wire is okay. Repair White/Green wire if it is open or shorted to ground.
  8. Reconnect wiring to BOO switch. Press clutch pedal. Clutch position switch should have continuity when clutch is released, and open circuit when clutch pedal is pressed. If clutch position switch is okay, go to next step. Replace clutch position switch if continuity is not as specified.
  9. Reconnect wiring to clutch pedal position switch. Unplug connector from Vehicle Speed Sensor (VSS), located at lower rear of transaxle. Check Black/White and Brown/Green wires between VSS and speed control module for continuity and for short to ground. If wires are okay, go to next step. Repair appropriate wire if it is open or shorted.
  10. Reconnect wiring to VSS and speed control module. Connect digital voltmeter to Brown/Green and Blue/White wires at speed control module. Drive vehicle at speeds indicated in VSS OUTPUT VOLTAGE SPECIFICATIONS table. If VSS output voltage is approximately as specified, go to next step. If output voltage is not approximately as specified, replace VSS.
    VSS OUTPUT VOLTAGE SPECIFICATIONS

    Speed MPH (KM/H) Approximate AC Voltage
    0 (0) 0
    5 (8) 1.40
    10 (16) 2.10
    15 (24) 2.80
    20 (32) 3.40
    25 (40) 3.85
    30 (48) 4.25
    35 (56) 4.55
    40 (64) 4.80
    45 (72) 5.00
    50 (80) 5.20
    55 (88) 5.40
    60 (96) 5.50
  11. Turn ignition off. Unplug speed control switch connector at clockspring. Turn ignition on. Measure voltage at Black/White wire at clockspring connector. If voltage is greater than 10 volts, go to next step. If voltage is not greater than 10 volts, repair Black/White wire.
  12. Turn ignition off. Measure resistance of Black wire between clockspring/speed control switch harness connector and ground. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair Black wire.
  13. Unplug speed control switch connector. Measure resistance between Blue and Black wire terminals of switch connector while pressing buttons as specified in SWITCH RESISTANCE SPECIFICATIONS table. Press only one button at a time. If resistances are as specified, go to next step. If any measurement is not as specified, replace switch assembly.
    SWITCH RESISTANCE SPECIFICATIONS

    Button Ohms
    ON Greater Than 10,000
    OFF Less Than 5
    SET/ACCEL Approximately 680
    COAST Approximately 120
    RESUME Approximately 2200
  14. Reconnect wiring to control switch assembly. Unplug clockspring/switch connector. Measure resistance between Yellow/Blue and Black wire terminals of clockspring side of connector while pressing buttons as specified in SWITCH RESISTANCE SPECIFICATIONS table. Press only one button at a time. If resistances are as specified, go to next step. If any measurement is not as specified, replace clockspring assembly.
  15. Unplug speed control module connector. Check Yellow/Blue wire between clockspring/speed control switch connector and speed control module for continuity or short to ground. If resistance is less than 5 ohms and no short exists, go to next step. Repair wire if defective.
  16. Unplug connector from servo. Check all 6 wires between speed control module and servo for continuity or short to ground or another wire. If resistance is less than 5 ohms and no short exists, go to next step. Repair appropriate wire(s) if defective.
  17. Reconnect wiring to servo. At speed control module connector, measure resistance between each pair of wires specified in SERVO RESISTANCE SPECIFICATIONS table. If resistances are as specified, go to next step. If any measurement is not as specified, replace servo.
    SERVO RESISTANCE SPECIFICATIONS

    Wire Pair Ohms
    GRN/WHT - GRN 20,000-30,000
    GRN - ORG 40,000-60,000
    GRN/ORG - GRN 20,000-30,000
    BLU - GRN/BLK 40-70
    BLU - BLU/RED 150-210
    GRN/BLK - BLU/RED 110-140
    CAUTION: In the following step, do not connect Blue wire to ground for longer than one second.
  18. Using a fused jumper, connect battery voltage to Green/Black wire at speed control module connector. Connect Blue/Red wire to ground. Start engine. Momentarily connect jumper wire between Blue wire at speed control module connector and ground. Remove jumper wire. If servo arm pulled in when jumper was connected, go to next step. If servo arm did not pull in, replace servo.
  19. Turn ignition off. Unplug connector from speed control module. Check Black wire for continuity between connector and ground. If wire is okay, replace module. Repair wire if continuity does not exist.
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