Body Control Modules: Description

WARNING: Deactivate air bag system before performing any service operation. See appropriate AIR BAG RESTRAINT SYSTEMS article. Do not apply electrical power to any component on steering column without first deactivating air bag system. Air bag may deploy.

Body Control Module (BCM) performs the following functions: exterior and interior lighting control, battery rundown protection, chime, instrument cluster indicator control, power door locks, remote keyless entry and theft deterrent.

BCM communicates with components using class 2 data line. Class 2 data line is used by BCM to communicate with the Driver Information Display Module, Driver Seat Adjuster Memory Module, Electronic Brake Control Module (EBCM), inflatable restraint Sensing and Diagnostic Module (SDM), instrument cluster, Powertrain Control Module (PCM), Transfer Case Shift Control Module and Vehicle Interface Unit (VIU). Class 2 serial data uses the peer-to-peer method and message arbitration to manage data line traffic.

Signals that activate the BCM are known as "wake-up" signals. BCM wake-up signals include: door ajar switches, door handle switches, dome light, parking lights, key in ignition, key removed from ignition, key in door lock, when ignition switch is turned to RUN position, or inadvertent power.