Trunk Open
WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.
The BCM supplies a body system voltage signal to the trunk ajar switch to indicate the status of the trunk, ajar switch within the trunk latch will close providing a ground path for the ajar signal. The BCM will detect the voltage drop and will then communicate this status to the instrument cluster via serial data message. The instrument cluster, upon receipt of this message, will illuminate the Trunk Open message in the driver information center.