Engine Control Module: Service and Repair

ECM REPLACEMENT





Points to Observe When Replacing ECM
^ Some new ECM's are programmed with DTC 3-2-5 on delivery from the factory.
^ When changing an ECM from one car to another, remember to note any DTC(s) before removing component.
^ The ECM must not be removed from the car until the main relay has interrupted the supply. This may take up to 150 seconds after the ignition has been switched off.
^ Always check the ECM and base for bent or damaged pins and sockets. Fault may be due to this cause.





Removal of ECM
^ Check that supply from main relay has been interrupted. Easiest method is to place fingertips on the Idle Air Control valve. Cessation of valve vibrations means that main relay has interrupted supply to system.





^ Open ECM box cover and remove Motronic 4.3 ECM (module nearest engine).





Installation of New ECM
^ Inspect ECM pins and sockets in base for damage.
^ Install new ECM.
^ Switch ON ignition.
^ Display DTCs, if any.
^ Erase DTCs and reset adaptive functions.

Erasing DTCs and Resetting Adaptive Functions
^ It is important that DTCs are erased and adaptive functions are reset when the ECM is replaced or when work involves DTCs 2-3-1, 2-3-2 and 2-3-3, otherwise car may run poorly despite absence of faults. This may be carried out in one of two ways:





With Volvo System Tester Scan Tool (ST):
^ Erase DTCs and reset adaptive functions individually.





Using Volvo Diagnostics:
^ Adaptive functions are also reset when DTCs are erased by operating test button on Volvo DLC. To reset adaptive functions when no DTC is present, a DTC must first be created, for example by opening the MAF sensor connector for approx. 10 seconds.

NOTE: If using the ECM from another car, DTCs (if any) must be erased and adaptive functions reset as described above before ECM is reinstalled in car.