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 the lamp circuit is good.


DESCRIPTION
- PNP switch
The PNP switch assemble includes a transmission range switch. The transmission range switch detects the selector 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.

COMPONENT INSPECTION
Overdrive Control Switch





- Check continuity between two terminals.
Continuity:
Switch position "ON": No
Switch position "OFF": Yes

Park/Neutral Position Switch











1. Check continuity between terminals 1 and 2 and between terminals 3 and 4, 5, 6, 7, 8, 9 while moving manual shaft through each position.





2. If NG, check again with manual control linkage disconnected from manual shaft of A/T assembly. Refer to step 1.
3. If OK on step 2, adjust manual control linkage.





4. If NG on step 2, remove PNP switch from A/T and check continuity of PNP switch terminals. Refer to step 1.
5. If OK on step 4, adjust PNP switch.
6. If NG on step 4, replace PNP switch.

Throttle Position Switch
Closed Throttle Position Switch (Idle Position)








- Check continuity between terminals 5 and 6.

Wide Open Throttle Position Switch








- Check continuity between terminals 4 and 5.

A/T Fluid Temperature Switch








1. Make sure the A/T fluid warning lamp lights when the key is inserted and turned to "ON".
2. Make sure the A/T fluid warning lamp goes off when turning the ignition switch to "ON".
3. Check resistance between terminal 10 and ground while changing temperature as shown at left.