Door Switch: Description and Operation

This vehicle has four door ajar switches, one for each door. Each switch is concealed within and integral to its respective door latch unit. The switches are momentary leaf contact-type units that are actuated by the door latch mechanisms. A short pigtail wire and connector on each door latch connects the door ajar switch to the vehicle electrical system through its respective door wire harness. The door ajar switches cannot be adjusted or repaired and, if faulty or damaged, the door latch unit must be replaced.

The door ajar switches are actuated by the door latch mechanisms. When a door is closed and properly latched, its door ajar switch is an open circuit. When a door is open or only partially latched, the door ajar switch is a closed circuit. The rear door ajar switches are hard wired in series between a body ground and the Electromechanical Instrument Cluster (EMIC). On vehicles not equipped with the optional memory system, the front door ajar switches are also hard wired in series between ground and the EMIC.

On vehicles equipped with the optional memory system each front door ajar switch is hard wired in series between ground and its respective driver or passenger Memory Mirror Module (MMM) located in the front door. The MMM then sends electronic door ajar switch status messages to the EMIC over the Controller Area Network (CAN) data bus. Both the EMIC and the MMM read the hard wired door ajar switch inputs through internal pull-ups, then use these inputs to control many electronic functions and features of the vehicle.

The door ajar switches can be diagnosed and tested using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods may not prove conclusive in the diagnosis of the EMIC, the driver or passenger MMM, the CAN data bus, or the electronic messaging used to convey door ajar switch status to other modules in the vehicle. The most reliable, efficient, and accurate means to diagnose the EMIC, the driver or passenger MMM, the CAN data bus, and both the hard wired and electronic message inputs and outputs affected by the door ajar switch inputs requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.