Rear Compartment Lid Release System Components
- Body control module (BCM)
- Rear compartment lid unlatch switch
- Rear compartment lid latch
- Rear compartment lid unlatch relay
Figure 1: 14 Trunk Release Block Diagram
Rear Compartment Lid Release Operation
Rear Compartment Lid Release Switch
The BCM monitors a voltage signal to the rear compartment lid 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 vehicle doors are locked, the BCM will ignore the rear compartment lid unlatch switch, if the vehicle doors have been unlocked, the BCM will recognize the request and will provide voltage to the rear compartment lid relay.
Rear Compartment Lid Latch
When BCM receives a rear compartment lid release command from the rear compartment lid unlatch switch, the BCM applies brief pulse of voltage to the rear compartment lid unlatch relay control circuit, which energizes the coil side of the relay. The switch side of the rear compartment lid unlatch relay then momentarily closes, supplying a brief pulse of battery positive voltage to the rear compartment lid latch. The rear compartment lid latch is continuously grounded and when it receives the voltage pulse, it will become energized and the latch will activate releasing the trunk lid so that the trunk lid may be manually raised to an open position.
The BCM may also get a rear compartment lid release command from the remote keyless entry module. When the trunk button is pressed on the keyless entry transmitter, a rear compartment lid 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 rear compartment lid.
Trunk Open Message
The BCM monitors the voltage level of the trunk ajar signal circuit which is normally at the system voltage when the trunk lid is closed. When the trunk lid is ajar or open, a switch within the latch assembly closes providing a path to ground for the trunk ajar signal circuit. The voltage within the signal circuit will then drop to 0 volts, the BCM will then detect the voltage drop and will send a serial data message to the instrument cluster. The instrument cluster will then display the Trunk Open message.