Body Control Module (BCM)

The BCM is the central gateway module for the CAN bus. This means the BCM is able to interpret any bus message on any vehicle network, convert and then re purpose that signal to another vehicle network thus allowing vehicle communications and operations between the different bus networks and vehicle systems.

The BCM on Left Hand Drive (LHD) vehicles is located behind the right side kick panel. For Right Hand Drive (RHD) vehicles, the BCM will be located behind the left side kick panel.

The BCM monitors the driver and passenger Lock/Uunlock switches, through the door lock switch status and the door lock switch return circuits. When the BCM receives a door lock or unlock signal from the driver or passenger door lock/unlock switch, the BCM provides a signal to the door lock/unlock motors, through the door lock control and door unlock control circuits. The door lock/unlock motors are integral to the driver and passenger door latches. The locking command is only carried out if the doors are properly shut and the locks unlocked. Conversely, the unlocking command is only carried out if the locks are locked.

The BCM also stores the power lock system customer programmable feature settings received from the radio menu options. The BCM uses these settings and internal programming along with hard wired and electronic message inputs to determine the proper outputs needed to produce each of the appropriate power lock system features.

The power lock system circuits are continually monitored and controlled by the BCM. When the BCM monitors a problem in any of the power lock system circuits or components, it stores a fault code or DTC in its memory circuit.

RKE Specific:

In the event that the vehicle is not equipped with PEKG, the RFH receives data signals from the RKE transmitter. These data signals can include the number of button presses and which button was pressed to determine the requested event. The RFH sends the request to the BCM which then reads this data to provide the appropriate hard wired outputs to invoke the proper RKE system features and responses. The BCM then interprets a rolling code from the RKE transmitter to validate that the transmitter is synced to the vehicle.

If these data signals indicate that the doors are to be remotely locked, the BCM sends the output for a single horn activation and turn signal lamps illumination when vehicle locking is complete.

The BCM receives deadlocking requests and commands all of the doors locked and sets the deadlock activation. The BCM will deactivate the deadlocking on request. Deactivation is always managed in parallel for all doors.

Also, on vehicle remote start requests, the BCM performs a central locking command upon successful engine starting.

Inputs 

• The BCM receives an input from the ajar switches to wake the module as well as the state of the VAP
• Vehicle speed and Accelerator position from the PCM for auto lock and unlock feature
• Door lock cylinder switch inputs to the BCM when a key is inserted
• RKE input requests for lock and unlock
• Customer programmable features from the radio

Outputs 

• Manages and controls the outputs to the power lock system and relays
• Turn signal lamp activation
• Horn activation
• Output to the IPC for illumination and indication messages