Principles of Operation (How Does it Work?)

The Door Switch Lock Function
When a door lock switch is moved into the lock position or a door lock cylinder is rotated to the lock position, the door lock switch grounds the lock circuit input to the Central Security Module (CSM). The CSM then provides 12 volts to one side of the door lock actuators contained in the door latch unit and simultaneously grounds the other side of the door lock actuators. This completes the door lock actuator circuit, causing the door lock actuators to rotate a cam assembly, which then locks the doors. The 12 volts that the CSM provides to the door lock actuators are provided to both door lock actuators from a single pin on the CSM connector.

The Door Switch Unlock Function
When a door lock switch is moved into the unlock position, the door lock switch grounds the unlock circuit input to the CSM. The CSM then provides 12 volts to the opposite side (relative to locking the door) of the door lock actuator(s) contained in the door latch unit and simultaneously grounds the other side of the door lock actuator(s). This completes the door lock actuator circuit, causing the door lock actuator(s) to rotate a cam assembly in the opposite direction, which the unlocks the door(s). The 12 volts which the CSM provides to the door lock actuator(s) are provided to each door lock actuator from the individual pins on the CSM connector.

The Liftgate Release
When the liftgate release switch is depressed, it grounds an input circuit to the CSM. When the CSM senses the ground, it sends 12 volts to cycle the liftgate release actuator.

Door Lock Cylinder Functions
Both the driver and passenger doors can be locked from either door lock cylinder. When the ignition key is inserted into either door lock and is rotated into the lock position, the linkage moves to rotate a cam in the door latch unit. When the cam in the door latch rotates, it mechanically moves the door latch (in the door in which the key is being used) into the locked position. The other door is locked electronically. As the cam in the door latch unit rotates to mechanically lock the first door, it also closes a switch in that door latch unit that grounds an input to the CSM. This causes the CSM to send 12 volts to one side and grounds the other side oft door lock actuator, which then rotates its cam assembly, locking the remaining door. Only one door can be unlocked from any one door lock cylinder. When the ignition key is inserted into a door lock cylinder and is rotated into the unlock position, the linkage moves to rotate a cam in the door latch unit. When the cam in the door latch unit rotates, it mechanically moves the door latch into the unlocked position.