Central locking takes 2 tries to lock- ideas?

[Rigmaster]

OK, so the wife has been mentioning that it takes 2 tries to get the central locking to stay locked. You have to lock the doors once, then they automatically unlock- then once you lock them the 2nd time, they (usually) stay locked.

My searching this board shows that it's probably one of the locks not locking- does this sound like the most likely cause?? If so, how do I figure out which one is not locking the first time?? It looks like all the doors lock knobs are working- so it must be the trunk lock or fuel door lock........I guess.

Car is a '91 535ia with BMW central locking.

Thanks!!

Bret.

[Robert K]

Bret,

This is your lucky day! I also have a 1991 535i that did the same thing and I know why it's happening. You have some wires that have worn through on one of the trunk hinges that are shorting out. I don't know why they cause the locks to automatically unlock, but they do. Until you repair the wires, it will continue.

On the driver's side trunk hinge, there's a black plastic cover. It covers the wires for the tail lights and the trunk lock solenoid. If you'll crawl inside the trunk, then slowly close the trunk, you'll see where the wires are constantly bending back and forth everytime you open and close the trunk. Somewhere inside the that bundle of wires, you have one or more that are either frayed or completely broken. I ended up putting in about 5-6 splices to repair mine. Once I did that, the locks locked first time, every time.

On the plastic cover around the trunk hinge, there are 3-4 clips that you can release with a small screwdriver that will allow you to remove the cover. Once you have it off, take a razor and slit the black tape covering the wires so that you can expose the wires. You'll actually want to start with the end right under the rear deck. Once you open it up, the damage will be evident. If a wire is in good shape but has a break in the sheath, you may be able to just apply some tape. For any broken ones, you'll have to use some similar wire and make some splices. Once you get all of them fixed, just rewrap the bundle of wires and put the plastic cover back on. I slighly repositioned the bundle under the shelf too. It's tedious (and sticky) work, but once you've fixed it, your locking problems will be solved. At least this was my problem and worked for me.

Grace and peace,

Robert K
1991 535i

[Dan in NZ]

I had that problem and it was just a blown fuse under the back seat. Worth checking those first.

[Javier]

a hinge harness damaged. You may be lucky and replace fuse not having an issue for a long time, but as soon as harness grounds again the proper wire, you blow fuse again, and issue comes back.

This picture shows the location of the fault in the the hinge harness.

Any of the three wires (Red/Black, White/blue, or White/Gren/Yellow) may cause F31 to blow if wire is grounded, and GM will loose immediately confirmation of locked trunk, causing the twice lock order requirement. This can be confirmed also as trunk lock will stop working normally (can not lock car trough trunk lock cylinder).

This picture shows the location of the fault in the hinge harness.

Javier

[slip]

a hinge harness damaged. You may be lucky and replace fuse not having an issue for a long time, but as soon as harness grounds again the proper wire, you blow fuse again, and issue comes back.

This picture shows the location of the fault in the the hinge harness.

Any of the three wires (Red/Black, White/blue, or White/Gren/Yellow) may cause F31 to blow if wire is grounded, and GM will loose immediately confirmation of locked trunk, causing the twice lock order requirement. This can be confirmed also as trunk lock will stop working normally (can not lock car trough trunk lock cylinder).

This picture shows the location of the fault in the hinge harness.

Javier

I have the same prob, except when locking. Checked all the wires and found 6 with the casings broken. Repaired those, but it's still double locking. I can lock and unlock all the doors from the boot lock, and all the fuses seem to be in order. What else should i look for?

[uscharalph]

OK, so the wife has been mentioning that it takes 2 tries to get the central locking to stay locked. You have to lock the doors once, then they automatically unlock- then once you lock them the 2nd time, they (usually) stay locked.

My searching this board shows that it's probably one of the locks not locking- does this sound like the most likely cause?? If so, how do I figure out which one is not locking the first time?? It looks like all the doors lock knobs are working- so it must be the trunk lock or fuel door lock........I guess.

Car is a '91 535ia with BMW central locking.

Thanks!!

Bret.

Mine was like Robert K said.

[Scott H]

and I know there is a short in the hatch wiring so the solutions make sense. I look forward to replacing the wiring at some point.....maybe my glass hatch will start opening as well!

Scott

[Kakaire]

Afew months ago mine would hold on the third attempt, and had stopped locking via the trunk. I had to open the trunk Hinge harness, found like six clean cut wires, I splice them according to color code, all is back to normal. I actually stopped getting the "Check Lic plate Lit" gong. Good Luck.

[Rigmaster]

Great help guys!!! Thanks!!!

Looks like some wiring repair is in the works for me sometime soon. Then I'll probably have to break down and do the same on the hatch of the 525iT- it's not doing the same thing, but it does give an intermittent "lic plate light" error, and the hatch/glass locks do not work they way they are supposed to.....



Thanks again,

Bret.