The BCM (Body Control Module) provides data to the ECM (Engine Control Module) via a communication network known as the Control Area Network or CAN Bus. It controls and monitors the various electronic accessories installed in the car body. In general, it controls the electric windows, the immobilizer system, the central locking system, among others.
The BCM also communicates with other on board control modules via the same CAN bus, although its main application is the control of the load drivers. To do this, it activates relays that perform actions in the vehicle when activated, such as closing the doors or other tasks.
Communication from the BCM to the module that requires it is carried by means of circuits that transmit LAN data. When a communication failure occurs, a DTC will be set to warn of the situation. When the U0422 OBDII fault code is set to indicate that the ECM received invalid transmission data from the BCM.