Circuit/System Description
WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) uses the rear compartment lid latch to determine the position of the trunk lid. When the trunk lid is open or ajar, the rear compartment lid ajar switch is closed, providing a ground path for the trunk ajar switch signal circuit. When the BCM detects that the trunk lid is open or ajar, a serial data message is sent to the driver information center (DIC) requesting the Trunk Open message be displayed.