Door Ajar Switch: Operation
WARNING: This page is about a different car, the 2004 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
The door ajar switches close a path to ground for the Central Timer Module (CTM) when a door is opened. The passenger side front door and both rear door ajar switches are connected in a parallel-series circuit between ground and the CTM, while the driver side front door ajar switch is connected in series between ground and the CTM to provide a unique input. The CTM reads the switch status through an internal pull-up, then sends the proper switch status messages to other electronic modules over the Programmable Communications Interface (PCI) data bus network. The door ajar switches can be diagnosed using conventional diagnostic tools and methods.