GM Service Manual Online
For 1990-2009 cars only

Power Requirements

The BCM has 3 main voltage feeds and 1 ground. Circuit 2340 (Battery Power 1) is used in order to provide power for the BCM's logic and internal driver operation. Circuit 1540 (Battery Power 2) provides power for the automatic door lock. Circuit 240 (Battery Power 3) provides power to the courtesy lights.

BCM Inputs

The following components provide direct input to the BCM. Other systems may use this input information in order to perform certain functions. Refer to Body Control System Schematics for BCM connector and terminal locations.

Input

Function

Accessory

This input determines when the ignition switch is in the ACC position and the RUN position.

Automatic Headlamp Link

Automatic headlamp diagnostics.

BCM Power (Battery Power 1)

This input provides voltage for the BCM operation.

BCM Ground

This input provides ground for the door lock operation.

Courtesy Lights On

This input provides the driver with the ability to request the illumination of the vehicle interior.

Crank

This input determines when the ignition is in the CRANK position.

Door Ajar

This input provides the door ajar status.

Door Lock Switch (Lock)

This input provides the door lock switch request in order to lock the vehicle doors.

Door Lock Switch (Unlock)

This input provides the door lock switch request in order to unlock the vehicle doors.

Driver Door Ajar

This input allows certain chime functions when the driver's door is open.

Driver Seat Belt Switch Unfastened

This input determines when the driver's seat belt is unfastened.

Exterior Lamps Off

This input determines when the Headlamp switch is in the off position.

Fog Lamp

This input determines when the fog lamp switch is grounded.

Headlamp On

This input provides the Headlamp switch position.

Ignition 0

This input determines the ignition switch status.

Ignition 1

This input determines when the ignition is in the following positions:

    • RUN
    • Bulb Test
    • START

Key-In-Ignition

This input determines when the key is fully inserted in the ignition key cylinder.

Key Read

This input reads the PASS-Key® II resistor pellet code.

Park Brake Applied

This input determines when the parking brake is applied.

Park Lamps Off

This input determines the headlamp switch position.

Rear Fog Lamp Switch

This input determines when the rear fog lamp switch is grounded.

RFA Link

This input provides an interface allowing the transfer of keyless entry information from the remote control door lock receiver (RCDLR).

Serial Data

This input provides an interface with the following components through the Class 2 serial data link:

    • The PCM
    • The EBTCM
    • The IPC

Tire Inflation Reset Switch

This input determines when the tire inflation reset switch is grounded.

Traction Control

This input determines when the traction control switch is grounded.

Trunk Ajar

This input determines when the rear compartment lid is ajar.

BCM Outputs

The BCM directly controls the following outputs. Other systems may request the BCM to control these outputs for certain functions. Refer to Body Control System Schematics for BCM connector and terminal locations.

Output

Function

All Door Lock

    • When active, this output supplies voltage to the door lock actuators and locks the doors.
    • When inactive, this output provides ground to the door lock actuators.

Courtesy Lamps

This output supplies the voltage to the courtesy lights, providing an inadvertent load (battery rundown) protection.

Driver Door Unlock

This output supplies ground to the door lock relay. This action provides power to the driver door actuator and unlocks the driver's door lock.

Horn

This output sends a ground signal to the horn relay. This action sounds the horn.

Ignition Reference Low

This output provides a ground to the ignition key cylinder for the PASS-Key® II resistor pellet.

Passenger Door Unlock

    • When active, this output provides the voltage to the door lock actuators and unlocks the doors (except the driver's door).
    • When inactive, this output provides ground to the door lock actuators.

RAP Relay Control

This output provides ground in order to energize the RAP relay.

Rear Compartment Lid Release Control

This output sends a ground signal to the Rear Compartment Lid Release relay. This action sounds the open the rear decklid.

Rear Fog Lamp Control

This output provides ground in order to energize the Rear Fog Lamp relay.

RFA Link

This output provides an interface allowing the transfer of keyless entry information to the remote control door lock receiver (RCDLR).

Serial Data

This output provides an interface with the following components through the Class 2 serial data link:

    • The PCM
    • The EBTCM
    • The IPC

Theater Dimming 1

This output supplies ground in order to activate the IP and door courtesy lamps.

Theater Dimming 2

This output supplies ground in order to activate the dome and the roof rail courtesy/reading lamps.

Truck Release

This output sends a ground signal to the rear compartment Lid release relay coil when the vehicle is in the PARK position. This action enables the rear compartment lid release relay. The rear compartment opens when the relay in energized.