Z3 Trunk central lock problem

[Gregkar13]

I recently noticed that the trunk doesn't lock via central locking system like the rest of the car. For example when i lock the car using the key on the driver's or passenger's door everything locks and unlocks normally except the trunk, same thing happens when i use the alarm remote. i cannot hear the trunk actuator work at all.

i bought a used actuator but still no luck, still doesn't working. i checked all the central lock fuses inside the fuse box and they are ok. next thing to check is the wiring loom, but before i rape the OEM BMW wiring loom isolation (don't want to do it) i was wondering if there was anything else to check or anything else i can do, like for example disconnecting the battery which i haven't done yet. Is there any possibility it's a trunk latch failure?

[Mr Bingley]

Does locking the trunk trigger the central locking of the doors?

[Gregkar13]

no, it doesn't, locking the trunk by iserting the key in the trunk lock only locks and unlocks the trunk nothing else

[deni2s]

I have similar issue with drivers door.

[Tazmanian Devil]

Check the comfort relay under the dash above the dead pedal. IIRC it is the blue rear relay.

http://www.bimmerforums.com/forum/sh...9#post26708669

[Gregkar13]

is it possible that this relay has anything to do with the central locking? i thought it had to do do only with the windows, i had changed this about 8 years ago.

[khammack]

Also check the wiring harness which runs into the trunk lid. It is a know weak point and can create many strange issues.

[Gregkar13]

i left that as a last resort, i don't want to rape the OEM wiring isolation

[Vintage42]

is it possible that this relay has anything to do with the central locking? i thought it had to do do only with the windows...

They are related.
"The window subsystem is powered by the "comfort" relay through fuse F13. The comfort relay is controlled by the central locking module."
​http://www.bimmerforums.com/forum/sh...9#post26708669

[Gregkar13]

Thanks a lot i will have a look as soon as i get some free time

[Gregkar13]

Does anybody knows this?: IF i have the trunk open looking straight at the latch and at the same time lock the trunk with the key, should i see the latch locking? or should the trunk be closed first?

[Vintage42]

Check the comfort relay under the dash above the dead pedal. IIRC it is the blue rear relay...

A thread on a relay and locking -- I don't know if the comfort relay and central locking relay are one and the same:
http://www.bimmerforums.com/forum/sh...control-module

- - - Updated - - -

I recently noticed that the trunk doesn't lock via central locking system like the rest of the car....

A post about the trunk harness:
https://zroadster.org/threads/boot-w...ng-issues.959/

[Gregkar13]

thank's for helping me, these problems are the worst for me because they are really annoying and you may never find the cause, or you may have changed 20 parts first until you track down the 1 part that was faulty in the first place

However i paid a visit to BMW yesterday, and for some reason($$$) the dealership insists i should install a new latch...

i think i will have to check that wiring loom asap before moving to other costly parts.

[Gregkar13]

It was DIY Saturday today so i took the decision and ripped the BMW loom, thankfully i was right and found 3 cable torn, one thick white cabel, one thin white-blue and another thin white-brown. I soldered them back awfully (don't got this AT ALL) and taped back everything to isolate them, the result was REALLY strange. Now when i lock the trunk with the key, everything in the car locks perfectly as it should, but when i lock either doors with the key the trunk still stays unlocked! same happens if i use the alarm to lock it. Next i check the comfort relay seems to be ok (seems to be repaired although i paid for a new one ) but i have some pictures if someone sees anything i don't see.








BTW i found these plugs that are not connected to anything, perhaps someone knows what are they for?

[Vintage42]

Now when i lock the trunk with the key, everything in the car locks perfectly as it should, but when i lock either doors with the key the trunk still stays unlocked! same happens if i use the alarm to lock it.

Perhaps the trunk lock actuator is faulty. Can you hear it trying to work when you turn the key in the door, or is there no sound?
No. 22 in RealOEM:
http://www.realoem.com/bmw/enUS/showparts?id=CH73-USA---Z3-BMW-Z3+1.9&diagId=41_0042
https://www.ecstuning.com/Search/SiteSearch/67118361140/ES2612027/

[Gregkar13]

No i cannoot hear it at all! Thankfully i have spare trunk actuator! But what are the chances i have at the same time a cutted wiring loom AND a faulty actuator? unless the actuator gone off when the wires cutted (short-circuit)

[Vintage42]

... i have spare trunk actuator! But what are the chances i have at the same time a cutted wiring loom AND a faulty actuator? unless the actuator gone off when the wires cutted (short-circuit)

Maybe that is what happened. Since you have a spare actuator, it won't take long to find out.

[Gregkar13]

I changed the actuator, still same situation, trunk locks everything but everything else doesn't lock the trunk. i am starting to believe there must be more cables damaged because i only cutted on small section of the bmw harness isolation

[Vintage42]

I changed the actuator, still same situation... i am starting to believe there must be more cables damaged because i only cutted on small section of the bmw harness isolation

You said you cut the harness sheath at one place and found three wires completely parted:
one thick white
one thin white-blue
and another thin white-brown.
It is possible that other wires are broken nearby in that harness. This post about an E39 BMW shows that can happen:
http://www.bimmerforums.com/forum/sh...8#post25612688
The post also shows that the trunk lock uses a gray-yellow wire. I don't know if a Z3 is the same.

This person had the same problem as you, and was told to "meter" the wires at the actuator -- use a circuit tester to find a dead wire:
http://www.bimmerforums.com/forum/sh...2#post27731822

Here is another thread about your problem:
http://www.bimmerforums.com/forum/sh...3#post28056033

[Gregkar13]

very helpfull info, i will check again when i got some free time and report back!

[Gregkar13]

I had one more cable torned, i soldered it and finally problem solved! Thank you all for your help!