Doors and Locks

CIRCUIT CHART
Circuit assignments for the Body Control Module (BCM) relating to doors and locks:

DOOR LOCKING/UNLOCKING
Door locking/unlocking, by Remote Keyless Entry (RKE) or driver/all door lock switches, is controlled through the BCM.

When a driver door unlock has been requested, the BCM switches circuit 1391 to battery voltage. This energizes the driver door unlock relay which supplies power to the driver door lock motor. Grounding is achieved through the closed contacts of the all-door lock relay. Grounding is also achieved through the windings of the all-door lock motors and the all-door unlock relay.

When an all-door unlock has been requested, the BCM switches circuit 194 to battery voltage. This energizes the door unlock relay which supplies power to the all-door lock motors. Grounding is achieved through the closed contacts of the door lock relay. Grounding is also achieved through the winding of the driver door lock motor and the driver door unlock relay.

When an all-door lock has been requested, the BCM switches circuit 195 to battery voltage. This energizes the door lock relay which supplies power to all-door lock motors. Grounding is achieved through the closed contacts of the door unlock relay and the BCM.

Lock/Unlock power application is limited by the BCM to 7 to protect lock motors.

ANTI-LOCKOUT
To help prevent locking your keys in your car, the BCM will unlock the drivers door when any interior door lock switch is activated, while a door is open and the key is still in the ignition.

DECKLID/LIFTGATE RELEASE
The decklid/liftgate release is controlled by the Body Control Module (BCM) circuit 362 providing battery voltage to the release solenoid. The BCM limits the amount of time the solenoid can be activated to 9 seconds to prevent damage to the solenoid. Reactivation may not be allowed for as much as 30 seconds.

Release of the decklid/liftgate can be initiated by either the transmitter or the decklid/liftgate release switch. Activating the decklid/liftgate release switch provides battery voltage to circuit 1576. Because remote keyless entry is an internal function of the BCM, no additional external wiring is necessary for transmitter input to the BCM. Decklid/liftgate release is not allowed by the BCM when vehicle speed is detected. The BCM receives vehicle speed serial data from the engine controller.

The BCM also monitors the cargo lamp switch input circuit 737 to determine when the decklid/liftgate is open. When the Input is active the BCM sends a class 2 message to the cluster to turn the hatch ajar telltale. Function operates in ACC or RUN.

FUEL LEVEL
The BCM receives fuel level percentage data from the PCM. The BCM calculates the data and sends the results to the cluster class 2 to control the fuel gauge deflection.

ODOMETER
The BCM calculates vehicle mileage from rolling count speed messages provided by the PCM over class II. The BCM stores the mileage in memory with a maximum number of 999,999. The BCM sends the value to the cluster over class II to display the vehicle mileage. If the BCM is dead and replaced in the field, the last value displayed by the cluster must be entered in the new BCM.