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Control module

Control module


Control module

The Motronic primarily controls:


• the ignition (by means of the ignition coil and distributor)

• fuel injection (which is sequential).


The Motronic control module has an 88-pin connector and is situated behind the dashboard by the right-hand A pillar.

On removal of the power train, the control module connector and wiring are withdrawn through the bulkhead partition between the cabin and the engine bay.

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

Two of these important matrices are used to control ignition timing and fuel injection.

The control module is programmed for the B234 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. For this reason it must always be treated with great care in connection with fault diagnosis and the fitting of spare parts.

The control module is supplied continuously with current (+30 circuit) and will lose its adapted values and diagnostic trouble codes if the supply of current fails. If this happens, the car should be driven at 6000 rpm and engine-braked down to 2000 rpm five times so that the control module will be able to adapt the crankshaft position sensor.

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.



Manual/Automatic

The part number of the control module fitted to cars with a manual gearbox is different to that of the control module fitted to cars with automatic transmission.