For 1990-2009 cars

### 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. The BCM evaluates this information and controls certain body control systems by commanding outputs on or off. The BCM control inputs can be:

• | Sensors and switches that are directly connected to the BCM

• | Class 2 serial data received from other control modules connected to the class 2 serial data link.

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 control module capable of performing the required function will respond to the BCM message.

The BCM controls these functions:

• | Audible warnings--Refer to Audible Warnings Description and Operation .

• | Automatic door locks--Refer to Power Door Locks Description and Operation .

• | Automatic headlamp control--Refer to Exterior Lighting Systems Description and Operation .

• | Horns--Refer to Horns System Description and Operation .

• | Interior lighting--Refer to Interior Lighting Systems Description and Operation .

• | Keyless entry--Refer to Keyless Entry System Description and Operation .

• | Passlock theft deterrent--Refer to Immobilizer Description and Operation .

• | Retained Accessory Power (RAP)--Refer to Retained Accessory Power (RAP) Description and Operation .

• | Theft deterrent--Refer to Content Theft Deterrent (CTD) Description and Operation .

• | Wipers/Washer--Refer to Wiper/Washer System Description and Operation .

### Power Mode

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