Trunk Ajar Indicator
WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) receives a discrete input from the rear compartment lid ajar switch signal circuit. When the rear compartment lid release actuator releases the rear compartment lid, the rear compartment lid ajar switch, which is internal the rear compartment lid release actuator, is supplied with ground which causes the trunk ajar switch signal circuit to be pulled low. The BCM interprets this and communicates via GMLAN serial data with the instrument panel cluster (IPC). When the trunk is open/ajar and the vehicle is in any gear other than PARK, the driver information center (DIC) will display TRUNK OPEN. If the trunk is still open and the vehicles speed is greater than 4.8 km/h (3 mph) a chime will sound.