Control module

The transmission control module has a 35-pin connector and is situated behind the glove box in the cabin. It is programmed for the B204L, B234i or B258i engine and must be used only in a Saab 900 equipped with the appropriate engine version. The transmission control module processes input signals and information received from a number of sensors and other electronic systems. On the basis of the results obtained, it controls the engaged gear and shifting point according to the selected drive program (NORMAL, SPORT or WINTER).

Shifting takes place by means of the two solenoid valves S1 and S2, which are actuated by the transmission control module. The control module also determines if and when the torque converter's lock-up function is to be activated, which is done by means of solenoid valve SL. When shifting takes place, the transmission control module actuates solenoid valve ST in order to change the fluid pressure in the transmission. The transmission control module is continuously supplied with current (+30 circuit) and designed to run on a power supply of between 9 and 16 V when the car is being driven. Diagnostic trouble codes stored in the memory will be cleared if the power supply fails. Since the transmission control module can be damaged by electrostatic discharges, great care should be exercised when handling it in connection with fault diagnosis and storage.