If your car door won’t unlock with your remote key, like, for example, when you press a working key fob and a locked door won’t open but the others do, there could be a few different causes. We’ll cover what parts could be keeping your door from opening and how to diagnose it yourself. We also have plenty of how-to videos that can show you how to install a new part if you want to replace it yourself.
Why your remote key won’t unlock your car door
Broken Door Lock Actuator
The most common cause of a door not unlocking with your remote key is a broken door lock actuator. To keep from needlessly removing and installing a new door lock actuator, there are a few ways to diagnose a bad door lock actuator that we’ll discuss further.
Split or Torn Electrical Wiring
The electrical wiring to the door lock switch and the electrical wiring in the boot in the door jamb (section between the door and the cab) can split, wear, and tear, causing a faulty or intermittent electrical connection. Wires can get caught in the door, strip over time, or work less efficiently from outside elements affecting exposed areas.
Faulty or Broken Door Lock Switch
The door lock switch can break or wear from use over time, although this is unlikely if one car door won’t unlock but the rest do when you press the key fob. Luckily, if it is the door lock switch, they are inexpensive and an easy DIY job.
How to Diagnose a Car Door That Won’t Unlock with the Remote Key
Diagnose the Door Lock Actuator
Since a door lock actuator is the most common case for doors staying locked, we recommend starting there.
1. Test the Door Lock Rod
Try to lock the door mechanically. If the mechanical lock works and the rod shifts and unlocks as intended, the latch or the actuator is working. If the lock rod does not shift and unlock the door, the latch on the door lock actuator is probably frozen.
2. Find the Door Lock Actuator Electrical Connector
Find which electrical connector connectors to the door lock actuator. One of the connectors may be from another part like the dome light. You may have to look up the wire colors for each connector, inspect the size of the wiring (sometimes the thicker wires are for the actuator as it handles higher voltage), or, for example, disconnect the connector with the dome light on (dome light in this case will turn off when the connector is removed) to tell the connectors apart.
3. Test the Electrical Current to the Door Lock Actuator Electrical Connector with a Test Light
1. Test the Door Lock Actuator Electrical Connector for Power
Use a test light to test the door lock actuator’s electrical connector for power. The electrical connector should have a wire for the lock and unlock functions. Attach the end of the test light to a ground like the negative terminal on the battery.
Lightly press the test light to the terminal without pressing the terminal in or spreading it. Press the corresponding lock or unlock button to the terminal. If the light illuminates, the electrical connection is good. Repeat this for the other terminal. If the light illuminates for both terminals, the electrical connector is getting power.
2. Test the Door Lock Actuator Electrical Connector for Ground
Use the test light to test the door lock actuator’s electrical connector for ground. Attach the end of the test light to the positive terminal of the battery. Repeat the procedure described in the step above. If the test light illuminates for each of the connector’s terminals, the ground is good.
A test light that illuminates for power and ground means the electrical current to the door lock actuator is good and that the actuator is faulty if it’s the problem.
If the test light does not light up for the power or ground, the problem lies with the door lock switch or the electrical wiring.
How to Replace a Broken Door Lock Actuator Yourself
If the door lock actuator is broken on your vehicle, check out this video and see what the process is for removing and installing one. Find install videos for your make and model in 1A Auto’s how-to video library.