Door Not Unlocking Diagnosing Truck or Car Door Latch Problems

You go to unlock your car, you use the key fob. Hit the unlock button, go to get in, it's not working. So all the other doors are unlocking and locking the way they should, this one does not. Let's narrow it down. So we have the door panel off so we can check out what's going on. We connected the door lock switch back up. And the most likely cause is probably the door lock actuator but we want to be sure, we don't want to just order an actuator, throw it in and then have it not be right. So what we want to do is check out what's going on over here.

So mechanically, we can lock it and unlock it so the latch itself isn't frozen. Different cars are gonna have slightly different setups but we have a connector right here, you want to check the connector, take a look at the wires, make sure everything visually looks good. Look inside the terminals, see if those are spread or anything, those look pretty good. So let's check this for power and ground while we're checking the switch. So when I'm checking for power, I want to put the other end of the test light on the negative terminal on the battery.

All right. So let's check one side with a test light. Now you want to be careful, you don't want to push into the terminal, you don't want to spread it. We'll check the gray wire first. We'll use the test light and just lightly push on that. And then we'll try the lock button and we had power there, which is good. So we know we have power on the gray wire when we hit the lock button, now let's check for power when we hit the unlock button on the tan wire. Just slightly touch that and hit the unlock button and the test light worked. So that's good.

So we know we're getting power out of both wires the way they should when you hit the lock and unlock button. Now let's check for ground. And now when I'm checking for ground, I want to put the terminal of the test light on the positive. Now we're gonna test for ground. So I'm gonna put it on the tan wire and push the lock button and see if we have ground. And it lit up, so that means we have a ground circuit is good there. Now I'm gonna put it on the gray wire and do the same. And test it with the unlock, and that worked as well.

So we know the circuit all the way to the connector is good. So we need to find the wires for the actuator. And there's a connector right here that's on the door latch and there's also a connector up here and here, this one as well. And a lot of times one of the connectors is gonna be for the dome light if there's a dome light. And sometimes you're gonna have to look up the wire colors and see which goes to which or if one has the dome light on and then you disconnect it, the dome light goes off, you know which one was which. The other way to tell is the wire size. Sometimes the wires are thicker on the wires that go to the actuator because they send a lot of voltage to the actuator. These one seem to be a little bit thinner. So these are like signal wires, so there's not high voltage on this whereas there is 12 volts in the ground on these wires.

So now we know we need a door lock actuator, that's gonna fix our problem but if that wasn't the problem, what else could it be? A lot of times the wiring either in this area could be bad, the switch could be bad but if the switch was bad that doesn't really explain why the other doors work. Another area to check if you didn't have power or ground there could be somewhere in the wiring in between the cab of the vehicle and the door panel itself. The wires flex a lot and they get brittle and break.

So if you have a door lock that's not working properly, now you know how to diagnose it. If you enjoyed this video, please subscribe to our channel. Make sure you ring that bell, turn on all notifications so you don't miss any of our videos.

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