Door Ajar Switches
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The CTD system uses the door ajar switches in the door latch assemblies as one method to activate the alarm. The BCM monitors all door ajar switches via a discrete input from each door ajar switch. If the BCM receives a signal from a door ajar switch when the CTD system is armed, the BCM activates the alarm.