Power Door Locks Constantly Unlocking (1 Viewer)

[MrDrBosox]

Hi all,
I recently had the tailgate of my '98 cruiser replaced at a body shop. Since I got it back, whenever it's running the door locks are constantly unlocking. Every couple of seconds, with no discernible pattern, they unlock. Doesn't matter if I lock the doors, unlock the doors, nothing. The tailgate lock also only works if I use the switch inside the car. The key will not lock or unlock it. I spoke with the shop that did the work and they told me that they re-used the lock mechanism and the wiring from my original tailgate and only replaced the shell. All I can think of is they might have mixed them up and put in the wrong lock cylinder. Any ideas?

 

[gregnash]

There is s sensor in the rear lock mechanism. They could potentially have not connected properly or they could have messed with it. The sensor tells the locking ECU what position the locks are in and so if it is reading improperly or the lock cylinder was installed improperly it could be out of sync.

Since you are sure your key does not lock/unlock the lock itself I would venture a bet that either the sensor is messed up (maybe they tried to replace) or it is not connected.

 

[J1000]

No clue on the power locks but I recently replaced a hatch lock cylinder on my 80 and when I push the key all the way in until it seats the lock will not open. I have to pull it back out ever so slightly and then it will unlock. Probably just age and it's insecure in it's new home.

 

[MrDrBosox]

Thanks for the tips guys, as far as the key goes when I turn it it doesn't feel like the lock is engaging at all. Turns freely, just no results. Gregnash, if the sensor is messed up/ improperly connected, would the lock still engage and disengage from the switch inside the car? Your suggestion sounds more or less like what I was thinking.

 

[J1000]

Probably the linkage rod was not put back in or the plastic catch was broken off.

 

[gregnash]

Thanks for the tips guys, as far as the key goes when I turn it it doesn't feel like the lock is engaging at all. Turns freely, just no results. Gregnash, if the sensor is messed up/ improperly connected, would the lock still engage and disengage from the switch inside the car? Your suggestion sounds more or less like what I was thinking.

So there are basically two parts to the lock from what I remember
1. the mechanism/motor assembly that controls the electronic turning of the lock. This is separate from the lock sensor itself.
2. the lock sensor that senses the POSITION of the lock cylinder and relays that to the lock/anti-theft ECU. The system goes through a whole procedure when checking itself and if it senses that the lock cylinders MAY be out of sync it will cycle to try and sync them.
3. lock hardware that is separate from the motor that is what actually moves the latch mechanism to be able to operate the door.

So you could technically it could be any of those three potentials (along with possible breaks in the electrical lines elsewhere). There is a lock thread that I would suggest looking at as in the early sections of the thread someone documented removing the rear lock mechanism to replace the actuator motor. You can pretty easily pop the lower interior trim of the upper lift gate to take a look and see if there are any wires dangling or harnesses that are not connected.

 

[MrDrBosox]

Finally got a chance to dig around in there and found the problem pretty quickly. When the shop installed the whole thing in the new tailgate, they missed a connector for the sensor that checks the position of the cylinder. Cleaned it up a bit, plugged it in, and no more problem. Obviously not an expert, but it seems like the part that actually moves the lock mechanism had power and would function when you hit the lock buttons up front, and the unplugged connector was for the lock sensor.

 

[vjpkrmnc]

I just slammed my tailgate real hard tonight and now the remote won't lock the doors--on account of the truck thinking the tailgate is ajar. Seems like the same thing. The little red door ajar light is on on the dash. I can lock everything from up front but not with the remote. Where did you go digging to find that connector?