Liftgate Release Operation

Liftgate Unlatch Switch 

The BCM monitors supplies a 12 V signal to the liftgate unlatch switch so that when the switch is pressed, the voltage within the signal circuit is pulled low and in response, the BCM will detect the voltage drop and check the status of the door lock system. If the doors are locked, the BCM will ignore the request, if the All Doors Unlock has been commanded, the BCM will recognize the request and will provide voltage to the release relay.

Liftgate Latch Assembly 

When BCM receives a liftgate release command from the liftgate unlatch switch, the BCM applies brief pulse of voltage to the liftgate unlatch relay control circuit, which energizes the coil side of the relay. The switch side of the liftgate unlatch relay then momentarily closes, supplying a brief pulse of battery positive voltage to the liftgate latch assembly. The liftgate latch assembly is continuously grounded and when it receives the voltage pulse, it will become energized and the latch will activate releasing the liftgate so that it may be manually raised to an open position.

Keyless Entry Transmitter 

The BCM may also get a rear compartment release command from the remote keyless entry module. When the liftgate button is pressed on the keyless entry transmitter, a liftgate release request is sent to the remote keyless entry module, the remote keyless entry module will then send a serial data message to the BCM to command the release of the liftgate.