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Control module

Control module


TCS control module

The 35-pin TCS control module is located under the right-hand front seat which must be removed to provide access to the control module.

When the TCS throttle actuator motor is not supplied with power, the throttle butterfly is held in the open position by a spring.

When the ignition switch is turned to the Drive position, the actuator motor rotates the butterfly towards the wide open position for 128 ms and so ensures that it really is wide open . The actuator motor is then switched off (while the butterfly is still held in the wide open position by the spring) and after a further 128 ms the signal from the butterfly position sensor is stored as "wide open butterfly" in the control module.

As soon as the speed of the car exceeds 4 km/h and engine speed exceeds 600 rpm, the TCS throttle butterfly is synchronized with the regular throttle butterfly.

The first time the accelerator is fully released after starting and engine braking takes place, operation of the TCS butterfly, which closes fully for 128 ms, is checked afresh and its position is stored as "fully closed butterfly" in the control module. With the accelerator still released, the actuator motor will now be switched off for 256 ms and give the butterfly time to open by spring force to an angle of at least 25°.

Following this the TCS throttle butterfly is again synchronized with the regular throttle butterfly.

When the ignition is switched off or if a fault arises in the system, the power supply to the actuator motor is immediately switched off and the throttle butterfly is opened fully by spring force.

In the event of an internal fault in the control module, a diagnostic trouble code is generated, the TCS OFF lamp lights up and the Traction Control System is rendered inoperative.

As a spare part the control module is unprogrammed and must therefore be programmed with the aid of an ISAT in connection with installation. For the Saab 900 the TCS control unit is to be programmed according to whether the car in question is equipped with a manual gearbox or automatic transmission.

Control module power supply




Battery voltage +30

The TCS control module is supplied with battery voltage on pin 32. This voltage is used by the control module to control the throttle actuator motor.

If no +30 voltage is present, the TCS OFF lamp lights up and the system is rendered inoperative. If the +30 supply is interrupted, the control module will still retain any diagnostic trouble codes that are stored in its memory.

Battery voltage +15

With the ignition switch in the Drive position the control module is supplied with +15 voltage on pin 28. This voltage is used to activate the system.

Grounding points


The ground connections to pins 13 and 30 are joined together internally in the control module and from an electrical viewpoint comprise the same point. Duplication of the grounding points is carried out to improve reliability and safety.

With the ignition switch in the Drive position the control module's grounding points can be checked with a voltmeter by measuring the voltage across pin 13 and the battery's negative terminal and across pin 30 and the battery's negative terminal.

The voltage should be less than 0.1 V.