Drive Input Signal From Automatic Transmission

FAULT DIAGNOSIS, DRIVE
Input Signal From Automatic Transmission

Fault Symptom.
Drop in engine idling speed when the selector lever is moved from P or N.

DIAGNOSTIC PROCEDURE

1. Checking The DRIVE Function
Connect the Scan Tool. Ignition switch in the ON position.
Select "READ ON/OFF".
Select "DRIVE".
Check that an input signal is present by moving the selector lever from P and N to another gear position.

If the Scan Tool reading is correct, continue with point 3.

If the Scan Tool reading is not correct, continue with point 2.





2. Checking The Voltage Levels
Connect a BOB to the Trionic control module.
Take a voltage reading on pin 14, input signal from automatic transmission.
The nominal voltage is 0 V with the selector lever in position P or N and 12 V with the selector lever in position R, D, 3, 2 or 1.

If the readings are OK, continue with point 3.

If any reading is not OK, check the lead between pin 14 of the Trionic control module and pin 4 of the starting interlock switch.

If the lead is OK, check starting and charging systems.

3. Checking The IAC Valve
Fit an idle air control (IAC) valve that is known to be OK. Check whether the engine works.

If engine speed still drops, continue with point 4.

If engine speed does not drop, change the IAC valve.

4. Checking Engine Idling Speed
Drive the car on test and check whether the fault symptoms persist.

If the symptoms persist, refer to Before Replacing A Control Module.

If the symptoms have gone, the action taken to rectify the fault was correct, otherwise the fault is of intermittent nature.