Door relocks itself when I unlock it

[Russ]

My '95 door locks developed a strange problem:

From the inside, if I unlock the doors with electric button near the door handle, the plunger goes up and down again. Sometimes it relocks so fast the button barely moves up. If I manually pull up the plunger it fights me and pulls back down. I have to pull it up and hold it to get out of the car.

From the outside, the driver's door only unlocks with the key. Remote entry will make the plunger wiggle, it sounds like its trying to unlock but can't.

I suspect the remote entry module needs recapping which is pretty easy to check. I also suspect the door lock switch buried in the door, which is a PITA to reach, so hopefully it's not this.

Any ideas what else to check?

 

[vf2ss]

It might be worth checking out this thread [LINK] ... I had a similar experience where the lock mechanism one day just decided to start "fighting" with me and acting finicky. That was 15 years ago and after cleaning the door locks sliding actuators it's never happened again.

 

[Old Guy]

The first and easiest thing to do would be to unplug the keyless entry control unit and see if the problem goes away. The keyless unit does generate a relock signal; but, there is a 10 second delay for that signal so I don't think that is the problem. Given your description, I think that the keyless unit is not the problem; but, since it is relatively easy to isolate the unit that is where I would start just to rule it out.

Edit: On further thought it could be the keyless unit causing the problem if the lock signal output relay contact has stuck in the operate position. Whatever the actual problem, it will show itself if you disconnect the keyless unit.

I think it is more likely that one of the door lock / unlock switch circuits may be defective and shorted to ground generating a continuous lock signal. This includes the switch in the latch, the key cylinder switches and the rocker switches on the driver's doors (the passenger door rocker switch only controls the passenger door lock). The problem could be originating in the switch itself or on the associated wiring if the harness has chaffed and shorted to ground. It is also possible that the power door lock control unit has a problem; but, I think you need to rule out a door switch problem before testing the door lock unit (this would also depend on whether it is both doors or just the one door that are locking)

The direct way to assess this problem would be to get at the power lock control unit, unplug it and test the inputs using the input test described in the service manual. One thing to note is that the test description is deficient. It says that when you operate one of the switches there should be a ground on the input. What it doesn't say is that when the switch is not operated there should be no ground. What you are looking for is a continuous ground. That is the direct way. Unfortunately, the power door lock control unit is in the center stack which means that it is no treat to get at so you might want to start with the less direct method of pulling open the doors to test the door switches and the wiring. Unless you have some intuition, I would start on the driver side door and the lock rocker switch first because it is the easiest switch to get at. If it turns out that it looks like the problem is with the switch or wiring in the latch mechanism and you need to remove the latch mechanism make sure that you have new retaining clips for the lock rods on hand. From personal experience those clips will not survive removal.

 

[Russ]

So today when I start to take a look at this, the door locks are working fine. I go for a drive and stop at a store, they are pulling down again. When I get home, working fine again. Lol.

 

[Old Guy]

You could have an intermittent short circuit to ground in part of the wiring harness which may be caused by vibration or movement of the wiring harness (opening of the door).

 

[Russ]

Epilogue: While it was at the dealer for a NYS inspection I had them check it out. Turned out the battery tested weak and a new battery solved the problem.