System Components

BODY CONTROL MODULE (BCM)
The Body Control Module (BCM) type 4 controls the content theft deterrent system. The BCM monitors the status of the doors, lock cylinders, rear compartment lid, shock sensor, power door locks, and the keyless entry system.

The BCM operates the headlamps, horn, and the security indicator lamp according to the mode of operation the system is in. The BCM also communicates a fuel enable signal to the Powertrain Control Module (PCM) when the system is disarmed.

CHECKING FOR CORRECT BCM TYPE
Perform this procedure when checking the BCM type installed in the vehicle:
1. Turn the ignition switch to the OFF position.
2. Remove the MALL PGM fuse.
3. Turn the ignition switch to the ACC position.

The seat belt indicator flashes and the chime sounds 2, 3 or 4 times indicating the BCM type that is installed in the vehicle.

Verify that a BCM type 4 is installed on a vehicle with RPO UA6. Refer to the Service Parts Identification Label and the RPO Code list in the General Information for details.

If the vehicles has RPO UA6 but does not have a BCM type 4, then replace and install a BCM type 4. If the vehicle does not have RPO UA6 but has a BCM type 4, then refer to Body Control Module for more information. Body Control Module

KEY CYLINDER LOCK SWITCH
The door key cylinder locks have integral switches that signal the BCM to disarm the system theft deterrent system.

POWERTRAIN CONTROL MODULE (PCM)
The BCM interfaces with the PCM to either enable or disable fuel delivery to the engine. When the content theft deterrent system is armed, the PCM disables the fuel injectors. This action causes a crank no start condition when attempting to start the engine with the system armed.

When the content theft deterrent system is disarmed, the BCM sends a fuel enable signal to the PCM through the fuel enable circuit. The PCM then enables fuel delivery to the engine, allowing the engine to start.

REAR COMPARTMENT LOCK CYLINDER
The rear compartment lock cylinder has an integral switch that sends a signal to the BCM when the rear compartment lock cylinder is removed from the rear compartment lid.

SECURITY INDICATOR LAMP
The BCM controls the operation of the security indicator lamp. The BCM may be on, off, flashing slow or fast the security indicator lamp based on the current system operating mode.

SHOCK SENSOR
The shock sensor sends a tamper signal to the BCM if an impact to the vehicle occurs considered to be a vehicle tamper condition, or glass breakage.

THEFT DETERRENT RELAY
The BCM controls the theft deterrent relay, causing to turn on the headlamps during certain modes of operation.