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Diagnostic Procedure

  1. Check Fuse No. 1 (15A)  - Remove and check fuse No. 1 located in the internal fuse panel. If the fuse is okay, go to step  3. If the fuse is not okay, go to next step.
  2. Check Purple/Orange Wire Resistance  - Ensure fuse No. 1 is removed. Disconnect shift lock actuator connector located near ignition switch. Using DVOM, measure resistance of Purple/Orange wire between shift lock actuator wiring harness connector terminal and ground. If resistance is more than 10 k/ohms, go to next step. If resistance is less than 10 k/ohms, repair short Purple/Orange wire. Reconnect all connectors and retest system.
  3. Check Power Supply To Shift Lock Actuator  - Reinstall fuse No. 1. Disconnect shift lock actuator connector. Using DVOM, measure voltage between Purple/Orange wire terminal and ground. Turn ignition on. If battery voltage is present, go to next step. If battery voltage is not present, repair open Purple/Orange wire. Reconnect all connectors and retest system.
  4. Check Stoplight Operation  - Depress brake pedal. If stoplights turn on, go to next step. If stoplights do not turn on, diagnose BOO/BPP switch. See appropriate EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT.
  5. Check Power Supply Between BOO/BPP Switch & Shift Lock Actuator  - With brake pedal depressed, measure voltage of Red/Light Green wire between shift lock actuator connector and ground. If battery voltage is present, go to next step. If battery voltage is not present, repair open Red/Light Green wire. Reconnect all connectors and retest system.
  6. Check Ground Circuit Resistance  - With shift lock actuator connector disconnected, measure resistance between Black wire terminal and ground. If resistance is less than 5 ohms, replace shift lock actuator. If resistance is more than 5 ohms, repair open Black wire. Reconnect all connectors and retest system.
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