Circuit/System Description
WARNING: This page is about a different car, the 2016 GMC Acadia, 2016 Chevrolet Traverse, and 2016 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
The body control module provides a 12 V signal to each of the door ajar switch signal circuits and to the liftgate ajar switch signal circuit. When a door is opened, the normally open contacts of the ajar switch closes. With the ajar switch closed, ground is provided to the ajar switch signal circuit. The body control module interprets this and communicates via serial data with the instrument cluster which will display the door ajar icon.