P1301

DIAGNOSTIC TROUBLE CODE P13O1
(Cars With Automatic Transmission)
Torque limitation, signal low or too long.

Fault Symptom.
CHECK ENGINE lamp (MIL) on,
Poorer shifting performance.

Condition
Pin 51 is grounded for longer than 2.5 seconds.

Diagnostic Procedure.
1. The signal from the AF22 control module to the MOTRONIC control module, which is a request for torque limitation, is extremely short (about 250 ms) and may therefore be difficult to check.

Connect the ISAT to the AF22 control module. Select "TORQUE LIMITATION" in the "ACTIVATE" menu. When activated, "TORQUE LIMITATION" sends a signal to the MOTRONIC control module. At engine speeds above 3000 rpm the MOTRONIC system will then retard the ignition timing briefly by about 12°.

If the torque reduction function works, it can easily be heard by the change in the engine note.

2. If no indication of torque limitation can be heard as described above, check the lead between pin 51 of the MOTRONIC control module and pin 13 of the AF22 control module for shorting to ground.

3. If the cause of the fault does not come to light after carrying out the above diagnostic procedure, and no trouble codes are generated in the AF22 system, clear any trouble codes in the MOTRONIC system and drive the car on the road to check whether the codes are generated afresh.

If they are, continue at "Before Control Module Replacement" for further diagnostic instructions. Before Replacing A Control Module