Input Signal From the Auto Trans, Torque Limitation

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

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

Diagnostic trouble code: P1842
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 13 of the transmission control module and pin 85 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 transmission control module.
- Turn the ignition switch to the ON position.
- Connect the test lamp to the Motronic control module between:
^ pins 85 and 26.
- Connect an ISAT scan tool.
- Select "AUT TRANSMISSION".
- Select ACTIVATE".
- Select "TORQUE LIMITATION".
The test lamp should flash.

Lamp flashing?

YES
^ Continue with point 3.
NO
^ Continue fault diagnosis in the Automatic Transmission.





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 at "Before Replacing a Control Module". Component Tests and General Diagnostics
NO
^ The steps taken to rectify the fault were correct.