A power lock on a car not working — or worse, all the locks malfunctioning — can pose an obvious security issue for you and your property. A faulty automobile lock could also be a safety concern, should you become trapped in the vehicle.
If you’re having this problem, you probably wondered what caused the power door locks to stop working. Here’s a look at different power lock scenarios and what might be the root of the problem.
In most cases, you’ll need to take your car to your mechanic for a fix, but there are a few minor issues where you might be able to arrive at a solution on your own. Even if you do need to take your vehicle to the shop, it’s good to know more about this common car problem. Your detailed accounting of what’s happening will help your mechanic narrow down the culprit more quickly, so you can get it fixed fast.
Photo by Jeff Siepman on Unsplash
Your Key Fob Won’t Unlock the Door Remotely
If your key fob isn’t letting you unlock your car doors, it’s usually due to one of two problems:
- The battery in the fob is dead and needs to be replaced.
- The car battery is dead and needs a jump and/or replacement.
In the latter instance, most electronic vehicle key fobs have a hidden “valet key” that slides out and lets you open the door manually. Once in, if you can’t start the car but know the key fob battery is still good, you know it’s a car battery problem.
Image by Benbur121 on Wikimedia Commons
2020 Ford key fob showing battery and hidden valet key
Car Power Locks Not Working on Some Doors
Many of our clients say they’ve had problems with most of their doors working except one or two. This is nearly always due to one of three causes:
- A stuck button spring — the door won’t lock, and you’ll probably hear a stuttering sound as it struggles to engage (aka bouncy locks).
- A faulty door actuator — this is the part that connects the lock to the car’s electrical system.
- A physical problem with the lock mechanism — often the door lock will freeze in one position and must be manually released.
With a stuck button, you can usually lock that particular door manually from the outside when you’re done driving. But if all your doors won’t lock automatically as you set off in the vehicle, it can be a hassle, especially if you can’t reach behind you to manually press the button in question. That needs to be fixed by your mechanic, but until then, you can usually wrap a piece of duct tape around the base of the button to facilitate it locking until you can get an appointment.
Usually a stiff or stuck lock mechanism calls for some lubrication. Door stuck in a locked position and won’t shut all the way? With the door open, try releasing the latch by pulling on the door handle. You may also need to push the latch mechanism at the same time.
If you have a faulty door actuator (aka solenoid), usually no functions on that door will work — neither locking nor unlocking. That’s a job for your professional mechanic, as the part needs to be replaced and rewired. Actuators are reversible motors. When you press a switch, they move in one direction; press the switch again, and they go in the opposite direction.
How does your mechanic know it’s your actuator at fault, besides the symptoms you report? They can test the power supply to the actuator. If the actuator is receiving power but not operating the door lock, that’s the part at fault.
There’s one other less common thing that can cause one or more door locks to fail: leaving your windows open in the rain or exposed to sea spray. The wiring and lock mechanisms inside the door panel can become rusted or corroded. That’s another repair for your mechanic.
Image by Parzeus on Wikimedia Commons
Interior of car door showing door lock actuator
All Car Power Locks Not Working
If all the locks are malfunctioning simultaneously, you may have a blown fuse. This is the most likely scenario.
Another possible explanation is a more widespread wiring problem. Are you experiencing other electrical issues with the car?
- Difficulty starting or stalling
- Lights not turning on or dimming
- Radio or heater/AC not functioning
This will require some detective work on your mechanic’s part. It’s best if you don’t operate your power windows when this happens, lest they get stuck in the open position.
Power Door Locks Work Intermittently
If you have one door lock that’s starting to malfunction but sometimes works, it’s usually an actuator that’s beginning to fail. It’s recommended to see your mechanic soon, before the motor stops working entirely.
If all the doors only work intermittently, your key fob battery could be wearing out. Otherwise, it’s likely a wiring problem, like a loose connection. Sometimes the connection gets power, and sometimes it doesn’t. This isn’t entirely unusual with wires that eventually wear near door hinges. Definitely report that to your mechanic.
Power Door Locks Not Working Once Vehicle’s in Motion
Most vehicle models from the last two or three decades have a feature that automatically locks all the doors once you start driving at about 15-30 kph. If this doesn’t work for you, it could be due to a couple of problems:
- A stuck button (see above) that prevents all the locks from engaging
- Dashboard setting accidentally turned off (check the owner’s manual)
- A computer problem related to the automatic lock setting
If the first two causes don’t seem likely, your mechanic can run a diagnostic code test to see if something shows up on the vehicle’s computer.
Vehicle Doors Won’t Unlock from Inside
Doors that won’t open when you’re inside a car or van are clearly a serious problem. Usually, this only happens to one door, due to any of the reasons discussed above. But if it happens to all your doors, it could be caused by:
- Child safety locks engaged and need to be turned off
- Accidentally activating the deadlock feature in a high-end vehicle
- Car doors frozen on the outside in extremely cold weather
If this happens more than once or if you can’t track down the cause, be sure to see your mechanic ASAP. In the meantime, carry an emergency glass-breaking tool in case you need to exit in a hurry.