Body Control System Description And Operation: Notes
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2013 GMC Savana, 2013 GMC RV Cutaway, 2013 GMC Cutaway, 2013 Chevrolet RV Cutaway, and 2013 Chevrolet Express. However, it is still accessible from the selected car via links, so may be relevant.
The body control system consists of the body control module (BCM), communications, and various input and outputs. Some inputs, outputs and messages require other modules to interact with the BCM. The BCM also has discrete input and output terminals to control the vehicle's body functions. The BCM is wired to the GMLAN High speed serial data bus and the GMLAN Low speed serial data bus and acts as a gateway between them. If the BCM does not communicate the vehicle will not start due to the inability of the Engine/Powertrain Control Module (ECM/PCM) and Vehicle Theft Deterrent (VTD) Control Module to communicate without the BCM providing the gateway function.