The body control module (BCM) is an integrated module that combines functions and features from a normal control module and a body electrical center. There are four electrical interfaces that exist between the BCM and the rest of the vehicle. There are two connections from the BCM to both the body wiring harness and the instrument panel wiring harness. The BCM contains fuses and relays that are serviceable.

The main features of the BCM are:

The BCM is the gateway between class 2 serial data circuit and high speed GMLAN serial data circuit. The purpose of the gateway is to transfer serial data messages from one subnet to another.

The BCM performs multiple body control functions. The BCM can control devices directly connected to its outputs based on input information. The BCM evaluates this information and controls certain body control systems by commanding outputs on or off. The BCM inputs can be:

The BCM is also capable of controlling other vehicle systems that are not directly wired to the BCM. The BCM does this by sending specific messages on the class 2 serial data link or high speed GMLAN serial data link. The system capable of performing the required function will respond to the BCM messages.

Some of the other systems' functions that BCM controls or contributes to are:

The BCM controls electric power management following an idle boost and a load shed algorithm. The load shed control algorithm will deactivate electrical loads if the idle boost algorithm is unable to maintain system voltage. If idle boost is active for a certain amount of time and the system voltage is still below a set value, then load shed will command the heated seats, HVAC blower, and rear defog to deactivate periodically. The deactivations will be cycled such that the customer may not observe limited operation. The duty cycle will be controlled independently by each of heated seats, HVAC blower, and rear defog. If idle boost continues to be active, the engine RPM low, and the system voltage remains low, then load shed will command the heated seats, HVAC blower, and rear defog to deactivate completely. When this occurs, the DIC will display "Battery Saver Active". Once the idle boost becomes unnecessary or the engine RPM is above a set value, and the system voltage is above a set value, the load shed algorithm will command the heated seats, HVAC blower, and rear defog to resume normal operation.

The BCM is the power mode master (PMM). Refer to Power Mode Description and Operation for more information.