Circuit/System Description
WARNING: This page is about a different car, the 2016 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
The body control module will supply a 12 V signal to the driver and passenger door ajar switch signal circuits. The door ajar switches are integral to each door latch assembly. When a door is opened, the normally open door ajar switch closes. With the door ajar switch closed, ground is provided to the door ajar switch signal circuit. The body control module will detect the voltage drop and will communicate the door ajar via serial data with the instrument panel cluster which will display the appropriate door ajar message.