Body Control Module: Service Precautions

Fault Memory

CAUTION: Disconnecting the vehicle battery will cancel the fault memories of control units. For this reason, prior to disconnection of the vehicle battery fault memories should be interrogated and faults printed by the printer of a BMW Service tester. Investigate stored faults.


Ignition must always be switched off before disconnecting or connecting control-unit connectors.

Removal and installation of components, relays, fuse, etc. could cause the storage of faults in fault memories of control units capable of self-diagnosis. For this reason, fault memories must always be interrogated after working on the electrical system. Stored faults must be investigated and cancelled.