Body Control Systems: Description and Operation

Body Control System Description and Operation

The body control module (BCM) has a bussed electrical center integrated into the housing. Body control relays and fuses are installed directly on the BCM, which simplifies wiring and junction blocks on the vehicle. The body control system consists of the BCM and its associated controls. Battery positive voltage is provided to the BCM from IBCM BATT 1 fuse and the IBCM BATT 2 fuse in the underhood fuse block. The module grounds are wired to ground G201, G203 and G305. The BCM is wired to the GMLAN High speed serial data buss, and the GMLAN Low speed serial data buss, as well as discrete input and output terminals to control the functions of the vehicle's body.

Serial Data Gateway

The body control module (BCM) in this vehicle functions as a translator between the High and Low speed GMLAN busses. The 2 communication protocols use the BCM to translate communicated serial data messages between the control modules over the 2 serial data busses.

Power Mode Master

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

Body Control Module

The various body control module (BCM) input and output circuits are described in the corresponding functional areas indicated on the BCM electrical schematics. The BCM functions include the following:

* A/C compressor request-Refer to Content Theft Deterrent (CTD) Description and Operation (Content Theft Deterrent (CTD) Description and Operation) for the manual system.
* A/C cooling fan-Refer to Air Delivery Description and Operation (Air Delivery Description and Operation) for the manual system.
* Battery rundown protection (inadvertent power)-Refer to Interior Lighting Systems Description and Operation (Interior Lighting Systems Description and Operation).
* Bulb check-Refer to Instrument Cluster Description and Operation (Instrument Cluster).
* Chimes-Refer to Indicator/Warning Message Description and Operation (Indicator/Warning Message).

- Check gauges
- Door ajar warning
- Headlamps ON
- Key-in-ignition
- Oil reset
- Park brake warning
- Seat belt not fastened
- Turn signal ON

* Door lock interface-Refer to Power Door Locks Description and Operation (Description and Operation).
* Electronic power steering (EPS)-Refer to Power Steering System Description and Operation (Description and Operation).
* Engine coolant level sensing-Refer to Cooling System Description and Operation (Cooling System Description and Operation).
* Exterior and interior lighting control-Refer to Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation).

- Automatic lighting control
- Daytime running lamps (DRL)
- Fog lamps
- Park brake lights
- Turn hazard lamps

* Gauge control-Refer to Instrument Cluster Description and Operation (Instrument Cluster).
* Horn interface-Refer to Horns System Description and Operation (Description and Operation).
* Instrument cluster indicator control-Refer to Instrument Cluster Description and Operation (Instrument Cluster).
* Interior lighting-Refer to Interior Lighting Systems Description and Operation (Interior Lighting Systems Description and Operation).
* Key-in-ignition sensing-Refer to Indicator/Warning Message Description and Operation (Indicator/Warning Message).
* Parking brake state sensing-Refer to Brake Warning System Description and Operation (Brake Warning System Description and Operation).
* Retained accessory power (RAP)-Refer to Retained Accessory Power Description and Operation (Retained Accessory Power Description and Operation).
* Rear compartment interface-Refer to Power Door Locks Description and Operation (Description and Operation).
* Rear defogger-Refer to Rear Window Defogger Description and Operation (Rear Window Defogger Description and Operation).
* Remote function control-Refer to Keyless Entry System Description and Operation (without Accessory 2 Way Remote) (Keyless Entry System Description and Operation (Without Accessory 2 Way Remote))Keyless Entry System Description and Operation (with Accessory 2 Way Remote) (Keyless Entry System Description and Operation (With Accessory 2 Way Remote)).
* Seat belt use sensing-Refer to Seat Belt System Description and Operation (Description and Operation).
* Content theft deterrent-Refer to Content Theft Deterrent (CTD) Description and Operation (Content Theft Deterrent (CTD) Description and Operation).
* Vehicle theft deterrent-Refer to Content Theft Deterrent (CTD) Description and Operation (Content Theft Deterrent (CTD) Description and Operation).
* Washer solvent level sensing-Refer to Wiper/Washer System Description and Operation (Front) (Description and Operation).
* Wiper/washer-Refer to Wiper/Washer System Description and Operation (Front) (Description and Operation).