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Input Signal Circuit Problem

NOTE: This test applies to GS300 and GS400 only. For all other models, check stoplight switch and cruise control switch input voltages. See PIN VOLTAGE TESTS .

  1. Check Stoplight Switch Input

    Remove ECM with connectors connected. Turn ignition switch to ON position. On GS300, measure voltage (backprobe) between ECM connector E5 terminal No. 11 (Black/Blue wire) and ground. On GS400, measure voltage (backprobe) between ECM connector E7 terminal No. (Black/Blue wire) and ground. On all models, voltage should be less than one volt with brake pedal released, 10-14 volts with pedal depressed. If voltage is not as specified, go to next step. If voltage is as specified, perform next procedure listed in DIAGNOSIS BY SYMPTOM  table under TROUBLE SHOOTING.

  2. Check Stoplight Switch Circuit

    Check for faulty circuits between ECM and stoplight switch. See WIRING DIAGRAMS . Repair circuit(s) if necessary. If circuits are okay, go to next step.

  3. Check Cruise Control Switch Input

    While moving cruise control switch, measure voltage (backprobe) between ECM connector E5 terminal No. 23 (Red/Yellow wire) and ground. See Figure. Also, refer to CONTROL SWITCH INPUT VOLTAGE  table. If voltage is not as specified, go to next step. If voltage is as specified, perform next procedure listed in DIAGNOSIS BY SYMPTOM  table under TROUBLE SHOOTING.
    CONTROL SWITCH INPUT VOLTAGE

    Application Volts
    Neutral Position 10-16
    RESUME/ACC Position 0.6-2.3
    SET/COAST Position 1.9-4.7
    CANCEL Position 3.4-7.2

  4. Check Cruise Control Switch

    Disconnect cruise control switch connector. While moving cruise control switch, measure resistance between switch connector terminals No. 4 and No. 5. Refer to CRUISE CONTROL SWITCH RESISTANCE  table below. Also, see Fig 1. If resistance is as specified, go to next step. If resistance is not as specified, replace cruise control switch.
    CRUISE CONTROL SWITCH RESISTANCE

    Application Ohms
    MAIN Switch
    Off At Least 1 Megohm (Infinite)
    On Continuity
    Neutral Position At Least 1 Megohm (Infinite)
    RESUME/ACC Position 220-260
    SET/COAST Position 600-660
    CANCEL Position 1500-1600

  5. Check Circuit

    Check wiring and connectors between ECM and cruise control switch. Repair if necessary. If wiring and connectors are okay, go to next step.

  6. Check Indicator Light

    Check cruise indicator light. See appropriate INSTRUMENT PANELS article. Repair as necessary. If indicator light is okay, replace ECM.
Fig 1: Identifying Cruise Control Switch Terminals
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