2. The electric drive of door locks is driven by reversible electromagnets located in the doors. Lock switches have two working positions: locking and unlocking. When activated, the switch sends a ground signal to the door lock control unit to lock or unlock the doors. Depending on how the switch is activated, the control unit reverses the polarity of the electromagnets, allowing them to be used alternately as the power side (positive) and grounding sides are two sides of the electrical circuit.
3. On some vehicles, an anti-theft function may be built into the power locks. If you are unable to find the problem using the following general points, contact the dealer's service department or another service station that does not have the appropriate equipment.
4. Be sure to check the electrical circuit protection first. Some vehicles use a combination of switches and fuses.
5. Operate the door lock switches in both directions (locking and unlocking) with the engine off. Listen for clicks as electromagnets operate
6. Check the switches for electrical continuity. Remove the switches and have them checked by the dealer's service department or another specialized workshop.
7. Check wiring between switches, control box and electromagnets for electrical continuity. Repair the wiring if there is no electrical continuity.
8. Check the grounding of the switches or the control box.
9. If all but one locking solenoid works, remove the trim panel from the door in question (see chapter 11) and check for voltage at the solenoid with the lock switch activated. One of the wires must be energized in the locked position; the other must be energized in the unlocked position.
10. If the non-working solenoid receives voltage, replace it.
11. If the inoperative solenoid is not receiving voltage, check the relay for an open or short in the wire between the lock solenoid and the control box.
Note. A typical malfunction is a break in the wiring harness in the area between the body and the door, because opening and closing the door leads to fatigue wear of the wires and, ultimately, to their breakage.