GM Service Manual Online
For 1990-2009 cars only

BCM Functions

The body control module (BCM) performs multiple body control functions. The BCM can control devices directly connected to its outputs based on input information obtained from 2 sources:

    • Sensors and switches that are directly connected to the BCM
    •  By receiving information from other vehicle systems connected to the class 2 serial data link.

The BCM evaluates this information and controls certain body control systems by commanding outputs ON or OFF.

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. The vehicle system capable of performing a required function will respond to the BCM message.

The BCM controls these functions:

    • Audible warnings--Refer to Audible Warnings Description and Operation in Instrument Panel, Gages, and Console.
    • Interior lighting--Refer to Interior Lighting Systems Description and Operation in Lighting Systems.
    • Automatic door locks--Refer to Power Door Locks Description and Operation in Doors.
    • Automatic headlamp control--Refer to Exterior Lighting Systems Description and Operation in Lighting Systems.
    • Keyless entry (AUO option)--Refer to Keyless Entry System Description and Operation in Keyless Entry.
    • Passlock theft deterrent--Refer to Vehicle Theft Deterrent (VTD) Description and Operation in Theft Deterrent
    • Content theft deterrent--Refer to Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent
    • Retained Accessory Power (RAP)--Refer to Retained Accessory Power (RAP) Description and Operation

Power Mode Master

This vehicles BCM functions as the Power Mode Master (PMM). Refer to Power Mode Description and Operation for a complete description of power mode functions.