Power door lock system — general information
1. A power door lock system operates the door lock actuators mounted in each door. The system consists of the switches, actuators, a control unit and associated wiring. On some models, the power door lock system is part of the security alarm system. On these models, the power door lock system is more complex, and more difficult to diagnose. Therefore, home troubleshooting is limited to simple checks of the wiring connections and actuators for minor faults that can be easily repaired.
2. Power door lock systems are operated by bi-directional solenoids located in the doors. The lock switches have two operating positions: Lock and Unlock. When activated, the switch sends a ground signal to the door lock control unit to lock or unlock the doors. Depending on which way the switch is activated, the control unit reverses polarity to the solenoids, allowing the two sides of the circuit to be used alternately as the feed (positive) and ground side.
3. The following general guidelines should help you quickly identify and repair typical problems. If you’re unable to locate the trouble using these guidelines, consult a dealer service department.
4. Always check the fuses first (see Circuit breakers, fuses and fusible links — general information and your owner’s manual).
5. Operate the door lock switches in both directions (Lock and Unlock) with the engine off. Listen for the click of the solenoids operating.
6. Test the switches for continuity. Remove the switches and have them checked by a dealer service department.
7. Check the wiring between the switches, control unit and solenoids for continuity. Repair the wiring if there’s no continuity.
8. Check for a bad ground at the switches and at the control unit.
9. If only one lock solenoid doesn’t operate, remove the trim panel from the door with the bad solenoid (see Body) and check for voltage at the solenoid while the lock switch is operated. One of the wires should have voltage in the Lock position; the other should have voltage in the Unlock position.
10. If the inoperative solenoid is receiving voltage, replace the solenoid.
11. If the inoperative solenoid isn’t receiving voltage, check for an open or short in the wire between the lock solenoid and the control unit.