Power door lock and keyless entry system — description and check
Note: These models are equipped with a Body Control Module (BCM). Several systems are linked to a centralized control module that allows simple and accurate troubleshooting, but only with a professional-grade scan tool. The Body Control Module governs the door locks, the power windows, the ignition lock and security system, the interior lights, the Daytime Running Lights system, the horn, the windshield wipers, the heating/air conditioning system and the power mirrors. In the event of malfunction with this system, have the vehicle diagnosed by a dealership service department or other qualified automotive repair facility.
1. The power door lock system operates the door lock actuators mounted in each door. The system consists of the switches, actuators, lock and unlock relays, Body Control Module (BCM) and associated wiring. Diagnosis can usually be 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 actuators are mounted as part of the door latch. Remove the door latch for access to the door lock actuator. The lock switches have two operating positions: Lock and Unlock. These switches send a signal to the BCM, which in turn sends a signal to the door lock relays, the relays then send the needed voltage to each of the door lock solenoids.
3. If you are unable to locate the trouble using the following general steps, consult your dealer service department or qualified independent repair shop.
4. Always check the circuit protection first. Some vehicles use a combination of circuit breakers and fuses.
5. Check for voltage at the switches. If no voltage is present, check the fuse first. If the fuse is good then check the wiring between the
fuse panel and the switches for an open lead.
6. If voltage is present, test the switch for continuity. Replace it if there’s not continuity in both switch positions. There should be a voltage input and, when switch is depressed, voltage should be going out on the appropriate lead. Follow the wiring diagram for the actual wire and position on the switch. To remove the switch, use a flat-bladed trim tool to pry out the door/window switch assembly.
7. If the switch has continuity, check the wiring between the switch, BCM, door lock relay and the door lock solenoid.
8. If all but one lock solenoids operate, remove the trim panel from the affected door and check for voltage at the solenoid while the lock switch is operated. One of the wires should have positive voltage in the Lock position; the other lead should have positive voltage in the Unlock position.
9. If the inoperative solenoid is receiving positive voltage on one lead and negative on the other, the solenoid is most likely defective. Check the connections for good contact; if the connection is good, replace the solenoid.
10. If the inoperative solenoid isn’t receiving voltage or ground, check for an open or short in the wire between the lock solenoid and the relay. A good method of non-destructive testing is to squeeze the rubber corrugated tubing and search with your fingers for an individual wire. Follow the wire as far as possible and feel for any breaks in the leads.
Note: It’s not uncommon for wires to break in the portion of the harness between the body and door (opening and closing the door fatigues and eventually breaks the wires).
11. On the models covered by this manual, power door lock system communication goes through the Body Control Module. If the above tests do not pinpoint a problem, take the vehicle to a dealer or qualified shop with the proper scan tool to retrieve trouble codes from the BCM. Replacing of some components may result in programming issues. To avoid replacing good components always test thoroughly before any parts are deemed faulty.
Keyless entry system
12. The keyless entry system consists of a remote-control transmitter that sends a coded infrared signal to a receiver, which then operates the door lock system.
13. Replace the battery when the transmitter doesn’t operate the locks at a distance of 10 feet. Normal range should be about 65 feet.
14. For more information on key fob battery replacement, programming and additional keys see Key fob — battery replacement and adding additional keys.