Body Control Module: Description

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

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

The Body Control Module (BCM) or Truck Body Control (TBC) module 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 more than one systems operation.

TBC module 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.

TBC module communicates via a Class-II serial data bus for diagnostics and programming at the factory or authorized service center. TCM 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/illuminate due to the high resistance value.