Description & Operation

The Body Control Module (BCM) performs the following functions: HVAC afterblow control, battery guard, door lock and unlock, fuel level for DIC, retained accessory power, theft deterrent, exterior and interior lighting control, trunk release, time of day for radio display, rear defog, fuel door release, and vehicle personalization.

Signals that activate the BCM are known as "wake-up" signals. BCM is asleep when it is not controlling or monitoring the following wake-up functions: key in door lock switch, door ajar switches, power door lock switches, trunk ajar switch, trunk tamper switch, ignition on, and ignition accessory (ACC). BCM uses 2 separate data lines, the UART (Universal Asynchronous Receiver/Transmitter) and class 2, to communicate with other system control modules. UART system uses a master and remote transmitter communication process. BCM is the master and controls signals on serial data line by soliciting remote transmitters (system control modules) for information, then waits for correct response. UART remote transmitter control modules include: Electronic Brake and Traction Control Module (EBTCM), Continuously Variable Road Sensing Suspension (CVRSS), Road Sensing Suspension (RSS), and Sensing and Diagnostic Module (SDM).

Class 2 system uses a peer-to-peer communication process and is transmitted at a much higher rate than the UART system. Class 2 control modules include: Air Control Module (ACM), Body Control Module (BCM), Cellular Telephone (PHN), Climate Control Panel (CCP), Instrument Panel Cluster (IPC), Integrated Radio Controller (IRC), Powertrain Control Module (PCM), memory seat/memory mirror module, and Remote Function Actuator (RFA). BCM acts as an interpreter for data communication between UART and class 2 to satisfy need for communication of serial data between modules.