Operation CHARM: Car repair manuals for everyone.

Drive Position





Information about the current gear position, P-N or R-D-3-2-1, is sent from pin 11 of the transmission control module to the engine control module.

The Motronic 4.1 (4-cyl.) receives the signal on pin 86, the Motronic 5.2 (6-cyl) on pin 69 and the Saab Trionic receives the signal on pin 14.

When any of the gear positions R, D, 3, 2 or 1 is selected from gear position N, the transmission control module applies positive battery voltage (B+) to pin 11.

Otherwise the voltage on pin 11 is 0 V. The intention is to inform the engine control module that a gear position (forward or. reverse) has been selected.

The engine control module then ensures that engine idling speed is raised to compensate for this change in load.

Idling speed compensation is achieved by the engine control module opening the idle air control valve wider than normal so that a constant idling speed can be maintained.

In the event of no signal being received, engine idle speed will drop below 900 rpm (4-cyl.) or 800 rpm (6-cyl.) when DRIVE is selected and then slowly rise to normal idling speed.