Procedure 21

21. TCM Self-diagnosis Does Not Activate (PNP, Overdrive Control and Throttle Position Switches Circuit Checks)
SYMPTOM: O/D OFF indicator lamp does not come on in TCM self-diagnostic procedure even if the lamp circuit is good.

DESCRIPTION





- Park/neutral position (PNP) switch
The park/neutral (PNP) switch assembly includes a transmission range switch. The transmission range switch detects the selector lever position and sends a signal to the TCM.





- Overdrive control switch
Detects the overdrive control switch position (ON or OFF) and sends a signal to the TCM.





- Throttle position switch
Consists of a wide open throttle position switch and a closed throttle position switch.
The wide open throttle position switch sends a signal to the TCM when the throttle valve is open at least 1/2 of the full throttle position. The closed throttle position switch sends a signal to the TCM when the throttle valve is fully closed.

DIAGNOSTIC PROCEDURE

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NOTE: The diagnostic procedure includes inspections for the overdrive control and throttle position switch circuits.