TCM Self-Diagnosis Does Not Activate

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





- Park/Neutral Position (PNP) switch
The Park/Neutral Position (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





Check 1





Check 2





Check 3





Check 4





Check 5





Checks 6 and 7

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

COMPONENT INSPECTION
Overdrive Control Switch





1 of 2





2 of 2

- Check continuity between terminals 5 and 6.

PNP Switch





1 of 2





2 of 2

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 cable disconnected from manual shaft of A/T assembly. Refer to step 1.
3. If OK on step 2, adjust manual control cable.
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)





1 of 2





2 of 2

- Check continuity between terminals 5 and 6.
- To adjust closed throttle position switch, refer to Powertrain Management; Computers and Control Systems.

Wide Open Throttle Position Switch





1 of 2





2 of 2

- Check continuity between terminals 4 and 5.