Body Control System

WARNING: This page is about a different car, the 2002 Pontiac Grand Am and 2002 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.

The body control system consists of a Body Control Module (BCM) and associated controls. Battery positive voltage is provided to BCM from BFC/BATT fuse in driver side instrument panel fuse block. Module ground is wired to ground G202. BCM utilizes inputs Ignition 0, Ignition 1 and Ignition 3 to differentiate power mode ignition switch is in. Other subsystems also use these three ignition lines to identify which power mode they should be operating in. Engine run flag is used by vehicle subsystems to continue operating fail enable in event one of necessary ignition signals malfunctions during run power mode. BCM is wired to Class 2 serial data communication bus as well as discreet input and output terminals to control functions of vehicle body. Body Control Module (BCM) controls many vehicle functions. These functions include:

A/C compressor request
Keyless entry
A/C cooling fan
Interior and exterior lighting
Battery rundown protection
Audible warnings (chime)
Instrument panel cluster indicators and gauges
Theft deterrent
Washer solvent and brake fluid level monitoring
Key-in-ignition, seat belt and parking brake status sensing
Panic horn
Door locks and trunk release
Bulb check

BCM communicates with other systems over Class 2 serial data line to execute various vehicle functions. Communication between each system is accomplished by sending digitally coded messages, which consist of specific information system module must follow. Each system module is assigned its own recognition code, so that it can respond to appropriate messages.

Other modules that communicate with BCM over Class 2 serial line are Electronic Brake Control Module (EBCM), Instrument Panel Cluster (IPC), Powertrain Control Module (PCM) and inflatable restraint Sensing and Diagnostic Module (SDM).