Boot loom/central locking/key shenanigans

[John_B]

I know I can ramble, so I'll try to keep this short...

Before:
1x tombstone style key, remote central locking worked fine

What did I do?
Replaced boot-lid, transferred lock barrel and used a 'loom of doom' repair kit to join the loom (same kit I successfully used on prev Z3)

What's happened?
Central locking (whole car) is not working, attempts to reprogram the key following this guide have not worked, although I did notice that the red led on the key was flashing after I supposedly completed the steps

Before I chop out the loom repair and try again, can anyone suggest any steps or ideas to troubleshoot? All of the connections feel sturdy and I have double-checked the wires are correctly paired up, so I am inclined to think it could be a key or central locking issue rather than loom?

Also, are there any other parts I should have transferred between boot-lids, such as the solenoid?

Thanks

(edit to add: the centre brake light works btw, if that is relevant)

 

[John_B]

The plot thickens...

I have continuity checked each wire either side of the loom repair and it's good. I also transferred the solenoid from the old boot lid, and still nothing.

There are two identical brown wires in the boot loom - with them being indistinguishable, I thought they might be earths and therefore wouldn't matter if they got switched through the loom repair, but just to rule that out I switched them the other way too, and still nothing.

Incidentally I notice that after I try to reprogram the key (ignition on, off, key out, press & hold unlock, press lock button 3 times, release unlock) the red LED on the key is blinking slowly for around 10-15 seconds. So there is a chance the loom & boot lid are fine, but the problem is with the key transmitter or central locking receiver(s) - even though this problem started when I removed the old boot lid and cut the loom? Any suggestions what I can do to narrow down the problem area?

Next up I'm going to continuity check the rest of the boot loom, but I feel like I am clutching at straws at this point

 

[Pond]

I am sure all solid brown wires are earths. Do you have a wiring diagram for the boot/ alarm/ central locking?
If not I can scan them from the Bentleys manual if it helps.

Edit: I have just checked mine, as all the loom for the boot is stripped back and laying disconnected. One of the earths is for the boot lock itself, the other goes to the third brake light. There is no earth on either plug for the lock solenoid. HTH.

 

[John_B]

I am sure all solid brown wires are earths.

Thanks mate, that's what I was hoping. In which case I'm pretty sure that rules out the join in the loom since all 18 connections are proven good.

I'll check the rest of the loom for continuity, but if that doesn't unearth anything (excuse the pun) I might have to admit defeat and let a pro take a look.

I'm booked in at my local BMW specialist in a couple of weeks anyway for them to recommission the A/C, I'll ask them to look at the key/central locking at the same time if I've not gotten anywhere with it

 

[John_B]

Here's a thought actually - let's say for arguments sake the key is not transmitting the signal to remote lock/unlock the car - the central locking should still trigger on all doors and the boot when I lock the drivers door with the key, shouldn't it?

That is not happening, when I do the key in the door lock only the driver's door locks/unlocks - so would I be right in thinking that rules out the key?

 

[Duncodin]

I

Here's a thought actually - let's say for arguments sake the key is not transmitting the signal to remote lock/unlock the car - the central locking should still trigger on all doors and the boot when I lock the drivers door with the key, shouldn't it?

That is not happening, when I do the key in the door lock only the driver's door locks/unlocks - so would I be right in thinking that rules out the key?

If I sit in my car and press the button down on the door to lock the door the passenger door locks as well. When I then open the driver's door from the inside that unlocks the passenger door too. No keys or remotes involved.

 

[John_B]

If I sit in my car and press the button down on the door to lock the door the passenger door locks as well. When I then open the driver's door from the inside that unlocks the passenger door too. No keys or remotes involved.

I don't get any of that, the locks are all operating entirely independently.

So do we think it's looking like the brain of the central locking that's gone fishing?

Interestingly I just found this thread when searching for info about the central locking system, and I have the exact same flashing LED on the key they describe when trying to program the key. I'll read and digest this and attempt to follow it if it ever stops raining...

it could also be a fuse. This who saga started when I chopped the loom to swap the boot lid, so maybe something shorted and popped a fuse

 

[Pond]

it could also be a fuse. This who saga started when I chopped the loom to swap the boot lid, so maybe something shorted and popped a fuse

If you didn't disconnect the battery when working on the wiring, it could well be a fuse (or seven).
Seems too much of a coincidence that a 'module' is playing up after you repairing wiring.
I think I would try and find out what the blinking light on the key means. Is it indicating a fault? Is it trying to transmit but can't? Is it something else?

Car electrics are just too complicated for their own good (or ours) IMO. Give me 240v a/c, or 415v a/c any day.
Too many wires in a car don't really 'do' anything. They just send a 'signal' to other stuff which does the work. It's bloody confusing.

 

[John_B]

Well aren't I a numpty?

It was a fuse. All this time it was a smegging fuse, and I am flabbergasted I didn't think to check that from the start. Oh well.

In my (weak) defence, I did disconnect the battery before chopping the loom... however since I had to wait for the new loom to come, I reconnected it and was driving around for a few days with the cut end of the loom knocking around behind the carpet in the boot.

what a muppet. Anyway, fuse replaced, key reprogrammed and the central locking is fully working again. Hoorah!

 

[the Nefyn cat]

Just found this on platitudes-R-us.com.

 

[Pond]

Well aren't I a numpty?

It was a fuse. All this time it was a smegging fuse, and I am flabbergasted I didn't think to check that from the start. Oh well.

In my (weak) defence, I did disconnect the battery before chopping the loom... however since I had to wait for the new loom to come, I reconnected it and was driving around for a few days with the cut end of the loom knocking around behind the carpet in the boot.

what a muppet. Anyway, fuse replaced, key reprogrammed and the central locking is fully working again. Hoorah!

I had a similar numpty episode a while ago. I re-connected my battery and went to start the car. The dash lights all came on, then on start the lot just died. Nothing.

I thought I had done something stupid and blown a major fuse. Three hours, a good digestion of the Bentley electrical section and checking every single fuse in the car (from the 200 amp down) later turned out the negative battery terminal wasn't tight, as the thread had stripped on the clamping stud.

So the earth wasn't good enough for the high amperage of the start and pushed the terminal away from the battery post.

I still don't know how that happened, as I didn't take the nut off; just loosened it.