Throttle Position Signal

Fault Symptoms.
CHECK ENGINE lamp (MIL) on.
CHECK GEARBOX lamp on.

Conditions.
Diagnostic trouble code: P1624
Motronic 4.1, control module.

Diagnostic trouble code: P1785
Transmission control module (TCM).





Diagnostic Procedure.
1 Check The Wiring

- Remove the Motronic control module and the transmission control module.
- Check for continuity in the lead between:
^ pin 25 of the transmission control module and pin 38 of the Motronic control module.

Check the lead for open circuit and shorting.

Is the lead OK?

YES
^ Continue with point 2.
NO
^ Rectify the fault. Continue with point 3.





2 Check the output signal

- Plug in the Motronic control module.
- Turn the ignition switch to the ON position.
- Take a reading of the frequency on the connector for the transmission control module, between:
^ pins 25 and 22.
The frequency should be 100 Hz.

Is the reading obtained OK?

YES
^ Continue with point 3.
NO
^ Continue at "Before Replacing a Control Module". Component Tests and General Diagnostics





3 Final check

- Clear the diagnostic trouble codes.
- Implementation of driving cycle:
^ Drive the car at varying engine loads and rpm for 5 minutes.
- Evaluation of driving cycle:
^ Check whether the diagnostic trouble code has recurred.

Has the diagnostic trouble code recurred?

YES
^ Continue fault diagnosis in the Automatic Transmission.
NO
^ The steps taken to rectify the fault were correct.