Body Control Systems: Description and Operation

The body control system consists of a BCM and it's associated controls. Battery positive voltage is provided to the BCM from BFC/BATT fuse in the left hand Instrument panel fuse block. The module ground is wired to ground G202. The BCM utilizes inputs Ignition 0, Ignition 1 and Ignition 3 to differentiate the power mode that the ignition switch has bean placed in. The BCM is wired to the Class 2 serial data communication bus as well as discreet input and output terminals to control the functions of the vehicles body. The various BCM input and output circuits are described in the corresponding functional areas indicated on the BCM electrical schematics. The Body Control Module functions include the following.
^ Serial Data Communications
- Class 2 Serial Data Communications
- Serial Peripheral Interface (SPI)
^ A/C compressor request
^ Remote Function Control
^ A/C cooling Fan
^ Exterior and interior lighting control
- Daytime running lights (DRL)
- Automatic lighting control
- Fog lamps
- Interior lighting
^ Battery rundown protection (Inadvertent Power)
^ Chimes
- Key In Ignition
- Head Lamps On
- Seat Belt Not Fastened
- Turn Signal On
- Park Brake Warning
- Door Ajar Warning
- Check gages
^ Gage control
^ Instrument cluster indicator control
^ Theft deterrent
^ Engine coolant level sensing
^ Washer solvent level sensing
^ Key-in-ignition sensing
^ Seat belt use sensing
^ Brake fluid level sensing
^ Parking brake state sensing
^ Rear compartment interface
^ Horn interface
^ Door lock interface
^ Bulb Check

Data Line Communications
The BCM communicates on the following 2 separate data lines:
^ Class 2 serial data communications
^ Serial Peripheral Interface (SPI). The BCM acts as the master between the IPC.