Weird Central Locking Problem

[Dave Rutkowski]

Hoping for some ideas from the board here with a weird problem with the central locking on my '90 535i. For awhile now I've noticed that the trunk lock is not being actuated by the central locking. When I lock the trunk with the key, it locks, and when I unlock it with the key it unlocks. But when the key slot in the trunk lock is in the vertical position, the central locking doesn't lock/unlock the trunk.

Now the strange part - I started troubleshooting by opening the trunk, removing the interior carpet on the trunk lid, and then having someone lock or unlock the central locking (by working the button on the drivers door). When the trunk is open, everything works exactly as it should. I got in the trunk and closed it, and it stops working. Got out of the trunk, kept lid open, and it works just fine. Started closing the lid, and when I get to a point about 1/4 closed, that's when the central locking stops controlling the trunk lock.

I can't figure it out - for one thing, I can't figure out how the trunk lid knows that it is partially closed...there's the little pin in the lock mechanism that tells it when it's fully closed, but how does it know when partially or fully open? Also I played around with the locking actuator in the trunk lid, wondering if maybe when it rotates 90 degrees it stops working, but nothing there - it works any which way I hold it, as long as the trunk is mostly open.

Any ideas?

[Dave535Phoenix]

The wiring for the trunk lock has to move when the trunk opens. Could be that it's been chafing on something, and is grounding itself when the trunk closes.

I had a similar problem on a motorcycle a while ago. I'd blow a fuse when coming around to my parking spot...which was the only time I'd be using the clutch and have the bars turned at a certain angle. The clutch cable adjuster had been chafing on the insulation of a wire and eventually wore through. Took me a few fuses to figure that one out.

[dennyg]

The wiring for the trunk lock has to move when the trunk opens. Could be that it's been chafing on something, and is grounding itself when the trunk closes.

I had a similar problem on a motorcycle a while ago. I'd blow a fuse when coming around to my parking spot...which was the only time I'd be using the clutch and have the bars turned at a certain angle. The clutch cable adjuster had been chafing on the insulation of a wire and eventually wore through. Took me a few fuses to figure that one out.

I think your right about the wires grounding or coating wearing away. I remember looking at a 1994 530 and I opened the trunk all the way because the trunk shocks were weak. Well as soon as the trunk reached as far as it would go all the doors locked. Of course owner had key in ignition and had to call AAA to open the doors..........Lesson for all never leave keys in the ignition. hahahah

[gale]

Have you tried to re-sync the locks? Roll down the drivers window and hold the inside manual lock stub up while locking the door from the outside with a key.

Mine has gotten autistic a couple times where the doors would lock properly bot the trunk wouldn't. A re-sync fixed it.

[philbyil]

it is prolly a trunk wiring loom issue. Only way is to remove the plastic cover on the trunk lid arm and work your way down the loom, flexing it to (hopefully) discover the location of the break.

I went through something similar recently and ended up replacing the trunk lid lock actuator motor. It worked with the key and, with the remote, sounded like it was working but, when I checked it, it would not lock. I pulled the arm out of the actuator and it would unlock but didn't lock!

All the best



Hoping for some ideas from the board here with a weird problem with the central locking on my '90 535i. For awhile now I've noticed that the trunk lock is not being actuated by the central locking. When I lock the trunk with the key, it locks, and when I unlock it with the key it unlocks. But when the key slot in the trunk lock is in the vertical position, the central locking doesn't lock/unlock the trunk.

Now the strange part - I started troubleshooting by opening the trunk, removing the interior carpet on the trunk lid, and then having someone lock or unlock the central locking (by working the button on the drivers door). When the trunk is open, everything works exactly as it should. I got in the trunk and closed it, and it stops working. Got out of the trunk, kept lid open, and it works just fine. Started closing the lid, and when I get to a point about 1/4 closed, that's when the central locking stops controlling the trunk lock.

I can't figure it out - for one thing, I can't figure out how the trunk lid knows that it is partially closed...there's the little pin in the lock mechanism that tells it when it's fully closed, but how does it know when partially or fully open? Also I played around with the locking actuator in the trunk lid, wondering if maybe when it rotates 90 degrees it stops working, but nothing there - it works any which way I hold it, as long as the trunk is mostly open.

Any ideas?