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Many vehicles nowadays use the convenience of electric door locks, a security system that includes a solenoid or motor to move a locking and unlocking latch mechanism. It is a very reliable system, but subject to wear and tear as any other part in a vehicle. Car manufacturers use different power lock configurations, from simple to sophisticated anti-theft systems, depending on vehicle model. Here we will follow a general procedure to troubleshoot a common electric door lock circuit. With minimum knowledge of electricity or a desire to learn troubleshooting procedures, these steps will help you identify and fix any problem with the power locks in your own vehicle. So let’s start.
Step 1
Check the fuses and circuit breakers, especially if none of the power door locks work.
Step 2
Activate the power lock switch to its lock and unlock positions while listening for a distinctive click sound coming from the relay. If you cannot hear the click, go to the next step. If you can hear the click sound, go to Step 7.
Step 3
Lift the power switch off the door panel and check for voltage at the switch using a voltmeter. On some models, you might have to remove a cover or the door panel first. If there is no voltage present, go to Step 4. If there is voltage go to Step 5.
Step 4
Inspect the wire running from the switch to the fuse panel and look for an open or short.
Step 5
Check the switch for continuity using a multimeter. If there is no continuity, replace the switch. If the switch has continuity, go to the next step.
Step 6
Inspect the wire running from the switch to the relay and make sure there is continuity and good connections at both ends. Fix any open or short and test again.
Step 7
Test the power relay to make sure it is receiving voltage from the switch and it is functioning properly. Check the ground connection also. If the relay is receiving voltage but voltage is not coming out, replace the relay. If voltage is coming out of the relay go to the next step.
Step 8
Remove the door panel with the failed power lock if you have not done so already.
Step 9
Activate the switch to its lock and unlock positions while checking both wires for voltage at the solenoid. If there is no voltage reaching the solenoid go to the next step. If there is voltage present at the solenoid, replace it.
Check both wires between the solenoid and the relay. Fix any open or short and test again.
Tips
- It is a good idea to have on hand the electric door locks wiring diagram for your particular vehicle as you troubleshoot the circuit to easily locate and identify wires and components. Most vehicle service manuals come with wiring diagrams for the different electrical systems.
- You can buy a vehicle service manual at most automotive parts stores or consult one for free at most public libraries.
Items you will need
- Multimeter
