Description Of Operation, Control Module

The Motronic Primarily Controls:
^ the ignition (by means of the ignition coil module)
^ fuel injection (which is sequential).

The Motronic control module has an 88-pin connector and is located under the dashboard on the lefthand side.

In connection with removal of the power train, the control module's connector with cable is withdrawn through the bulkhead partition.

A number of sensors supply the control module with information which it processes by means of matrices or maps stored in its memory after optimization of engine performance.

These important maps are used to control ignition timing and fuel injection. The control module is programmed for the B308 engine and should be used for this engine only.

The control module can be damaged by electrostatic discharges or a short circuit on any of its outputs. Considerable caution should therefore be observed when handling it, such as in connection with fault diagnosis and the fitting of spare parts.

The control module is supplied continuously with power (+30 circuit) and will lose adapted values and diagnostic trouble codes if its power supply fails.
Adaptation is important for performance, driveability, fuel consumption and emission control. The control module should therefore not be removed unnecessarily or have its power supply disconnected in any other way.





Turning the ignition switch to the ON position activates the control module and grounds pin 27, causing the main relay to operate. The control module then waits for signals from the crankshaft position sensor.

The principal measured quantity for fuel injection comes from the mass air flow sensor. Substitute functions are provided for all sensors except the crankshaft position sensor.

The control module remains active for a certain period of time after the ignition switch has been turned to the OFF position. If the engine is restarted during this period, no pre-injection will take place when the starter motor begins to turn the engine over.