900 S Convertible L4-2290cc 2.3L DOHC (1996)
Engine Control Module: Description and Operation
Description Of Operation, 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On removal of the powertrain, the control module connector and wiring are withdrawn through the bulkhead partition between the cabin and the engine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.
