Torque Limitation

TORQUE LIMITATION
When shifting between certain gears the torque from the engine is reduced in order to make the shifting smoother and to reduce the wear on the transmission.

In order to control this, a signal is sent from pin 13 in the Transmission Control Module (TCM) to pin 51 in the ECM. The TCM knows when to shift gear and informs the MOTRONIC ECM about this. Torque limitation is carried out by the MOTRONIC ECM, which reduces the ignition causing the torque to fall.

The signal between the control module is different for 4-cyl and 6-cyl engines.

4-cyl:
There is normally battery positive voltage on the signal cable. If the TCM requests torque limitation, it activates pin 13 to 0 V (ground) for a period of time which is proportional to the desired reduction. Maximum time is 250 ms.

6-cyl:
There is normally battery positive voltage on the signal cable. If the TCM requests torque limitation, it reduces the voltage on pin 13 to 0 V using a 100 Hz PWM signal. The pulse ratio is proportional to the desired reduction.

The TCM can generate 8 pre-determined pulse ratios between 9% and 92%, which should result in ignition angles between -5° and +30°.

The above pulse duration corresponds to 0.9 ms to 9.2 ms.