Although power door locks are very effective in their work, they usually develop many problems. The cool thing is that you can easily troubleshoot the problems and correct them.
How to Troubleshoot Power Door Locks
If none of the locks work you should take a look at the fuses and circuit breakers. You should activate the power lock switch to its lock and unlock positions while listening for the click sound that comes from the relay. If you hear the click sound you should test the power relay to determine if it's receiving the right voltage from the switch.
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If the relay is receiving the right voltage, but the voltage isn't coming out you should replace the relay. If the voltage is coming out of the relay, chances are that the motor has corroded internally and you need to clean it. If you have the skills you should dismantle the motor and clean it. If you don't have the skills you should ask a professional to help you with the cleaning.
If one or two doors have stopped working, the problem must be within the doors. What you need to do is to remove the door panels and check if the motors have 12 volts. You should note that you need to confirm this while holding the driver's door button at the lock position. You should also check the voltage in the unlocked position.
If you get 12 volts in both the lock and unlock positions you should take a look at the motors. If you don't get 12 volts in the motors chances are that one or both of the wires are broken in the door hinge area.