Body Control Module: Description

NOTE: Body Control Module (BCM) may also be referred to as Truck Body Control (TBC) module.

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.

The Body Control Module (BCM) is designed to process various input information and send the necessary electrical responses to the other control modules. Input information has an interrelation to more than one output, therefore, if one input fails, it can affect the operation of more than one system.

BCM also controls operation of audible reminders, warning, power door locks, interior and exterior illumination. Module can time-out and turn off inadvertent load and also provides retained accessory power. Module is designed to interface with the Remote Function Actuator (RFA) subsystem to provide remote operation of certain vehicle features. The module also provides vehicle security with an integrated PassLock(R) system.

BCM communicates via a Class 2 serial data bus for diagnostics and programming. BCM supplies a buffered voltage to various sensors and switches through internal resistance in the module. Always use a DVOM with 10 megohm impedance for accurate voltage readings. A test light might not even turn on/come on due to the high resistance value.