| Diagnosis and Testing Refer to Wiring Diagrams Section 501-14, for schematic and connector information. Principles of Operation 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 all 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 (relevant to locking the door) of the door 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 then 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 All the 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 doors are locked electronically. As the cam in the door latch unit rotates to mechanically lock the first door, it also closes a switch in that doorlatch unit that grounds an input to the CSM. This causes the CSM to send 12 volts to one side and grounds the other side of the door lock actuator, which then rotates its cam assembly, locking the remaining doors. 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. Self-Test The CSM is equipped with a manually activated self-test. When self-test is activated the central security module (CSM) will give visual and audible response every time an input signal is received from an actuator. To activate the self-test mode, press the hood switch seven times within six seconds. Once the CSM has entered self-test mode, the module will sound the horn and flash the turn signal lamps once to acknowledge the input. The following are inputs to the CSM that can be tested while the CSM is in self-test mode: - Remote transmitter
- Hood switch
- Door entry switch(es)
- Liftgate entry switch
- Driver door lock motor set/reset switch
- Passenger door lock motor set/reset switch
- Liftgate anti-theft inhibit switch
- Integrated lock/unlock switches within power door lock actuator
Inspection and Verification NOTE:Make sure that the battery is fully charged before starting electrical diagnosis. NOTE:Before carrying out the CSM self-test, make sure that all the doors are open. - Verify the customer concern by operating the system.
- Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart | Mechanical | Electrical | - Binding latch mechanisms
- Binding linkage
- Misaligned door
| - Central junction box (CJB) fuse 25 (20A)
- CJB fuse 30 (7.5A)
- Wiring harness
- Loose or corroded connection(s)
- Circuit
- Door lock switch
- Door lock actuator
| - If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the concern is not visually evident, verify the symptom and refer to WDS/FDS 2000.
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