Was due to take my son out today, after washing the car this morning I decided to have a go at sourcing the reason that the aftermarket alarm/immob no longer responds to the key fob (having to manually lock/unlock car via passenger door).

So I tried to source the location to where the the lead from this alarm box of tricks (sits in the central cubby hole) leads to. Im 99% sure that the LED on this box used to light up, and that the timing of it no longer lighting up corresponds with the remote central locking/alarm fob no longer working.
Probably just a fuse I thought..

A while later I cannot source where the lead runs, and start to take the dashboard panels apart to get more access.. then I find that the box lead has been cleanly cut!

Not only that, but for the life of me I cannot find the other end of the cut cable anywhere. I have no idea how this could have been sheared during my ownership, but like i said, im sure this box was lit up at one point.
However, whats worse is that I did at one point find a black matching cable, and thinking it to the other end, I tried to pull it through, it gave some resistance then suddenly came out cleanly.. but wasnt the cable I was expecting to see…

As you can see it looks like an earth lead of some description, and its attached to a cross member in the drivers foot well. I’ve obviously pulled it neatly out of whatever it was previously attached to. As a note, it was originally routed upwards, towards the dash cluster (possibly)

Holding this freshly tugged cable I started to worry that I may have affected something electrically now, so attempted to start the car. It now turns over, runs for a approx 2 seconds, then cuts out. Every single time its the same result.

For the life of me I cannot source where the hell ive pulled this cable out from. Ive taken the dash apart as much as I physically can. I can see a small brown box with two small brown cable seemingly coming from it with exposed ends:

But its REALLY hard to get my hand to this box to see what it is or inverstigate these wires. The brown wires are a much thinner gauge than the ‘earth’ cable in the photo above – and theres two of them.. so I cant see how these three could once have been connected.

My questions are, how could I have stuffed the car starting by pulling this one simple lead out?
What could this lead possibly be and have been formerly attached to?

The alarm box/reciever with sheared cable is just a plain mystery. I’ve just opened it up and it doesnt appear to have any internal battery. How could I have once had a working remote central locking system if this receiver never had any power?.. If the cable was cut during my ownership, how on earth did it happen? and where is the other end of the cable??

It seems as though my car has now decided to trigger an immobiliser function, I have no idea if this is related to the cable I pulled out or not.. but I have very limited and very poor undertanding of electronics in general. Im wondering if the ECU (seemingly bolted to the floorpan underneath the heater matrix) or something simliar is now detecting a short/open circuit and cutting the ignition as a result?

Someone please help! My hands are cut to shreds, my day is ruined, I seriously doubt ill ever get this dash back together properly again.. but if I cant get the car going I certainly cant afford to pay a garage to do so for me either.
For reference, its a cabrio golf with auto box.

I can’t help much, but I can tell you that brown is earth on the standard German wiring colour code.

Second picture, you can see the brown colour under the extra black insulation and it’s connected to the body by that bolt.
I would guess that the bare end has pulled out of a terminal now, so something that should be connected to earth no longer is.

Third picture, I take it you know the plug is out of that box ?

Thanks for the reply.

Yes, I assumed it was earth by the hidden brown sheath under the black insulation, and also the fact that its a thicker gauge than most other wires.
It was indeed me that pulled the other end from whatever terminal it once attached to, but for the life of me I cannot trace this terminal.
Wherever it is, it seems critical as the car now will not start.

Third picture, yes, I removed the plugs to see if the earth cable was supposed to be attached somewhere. I took the pic for reference after I had been messing around with it.

The cutting out after 2 seconds is (or, most probably is) the immobiliser.

The black box in pic 1 looks like an aftermarket item. The cables that are loose, they could be anything, the only way to find out is to have a look at connectors that have a cable missing. Or, could they be joined together?
I’d be stripping out bits of trim/dash tomorrow to get better access.

Ive stripped out pretty much as much dash off as I possibly can now.
I’ve just learned that the brown box in the second pic is a factory Siemens immobiliser, ill take another look at the wiring leading from it tomorrow to see if my mystery black cable was spliced onto it at some point.
The two exposed cables are still a mystery, although they lead out of one of the plugs leading into the factory immob.

I spent hours looking for a connector with cables missing, no joy. Access is nigh on impossible too, so frustrating

It’s a guess – but the 2 exposed brown wires could have been in the same earth connection as the thick one you pulled and were pulled out at the same time?

**** if I know where this magical connection needs to be made..

More back breaking required tomorrow to investigate

Yup, I’d say that too, the three wires were joined together and completing a earth which is bypassing the factory immobiliser.
The first pic looks aftermarket as has been said, maybe a reciever unit for the remote fob?

Yeah I figured receiver for the remote, but the RCL was working fine when I bought the car last year and stopped working a few months ago, hence my surprise to find that cut wire on the receiver.. Can’t see how it got cut whilst hidden in the depths of my dash

Will have to check the earth theory tomorrow, i did half heartedly hold all three exposed wires together at one point and started the car, same issue

The cable in picture two looks like a an aerial coax cable. See if there is a centre conductor burried in there somewhere.

Would that have any bearing on the immobiliser though?

And would it still be fixed at the cross member if a co-ax?

Pic 2 Is a Aerial lead.

Check your radio still picks up a signal. If it does, it may have been a lead to an old hands free kit or simular.

Your pic 2 shows the lead going through the dash above the pedals whilst a Google image search shows the aerial on your car should be on the nearside so I can’t work out why the lead would be going across the offside.

Can’t help with the non running though sorry.

It’s not going through the dash (crossmember) it’s bolted to it. I’ve had my hands on the antenna earlier, on the meat side as you mentioned.
I don’t think it’s an ariel in pic 2

Will have to check the earth theory tomorrow, i did half heartedly hold all three exposed wires together at one point and started the car, same issue

You’d have to touch them to the chassis as well – or something else earthed – if they were originally in a single connector attached to earth.

Job done, it was a grounding issue relating to all 3 cables not being sufficiently connected together.

I went back and clamped them together, and right away I heard a relay click. Car started and ran first time.

Soldered together, jobs a goodun. Sod the remote alarm, I’ll use my key for a good while yet. Lost enough of a glorious weekend to this stupid ground connection. After the contorted positions I had to hold to access the bits I needed to, i feel like I’ve been hit by a truck!

Excellent result there!
Its an absolute killer working in / under the dash, especially if you’re 6’5″ like I am.
You’ll generally find that car wiring has very little slack, and the wire will normally “lie” more or less where it should be naturally.

Blimey, yes 6’1″ was a push, literally laying on the drivers seat on my back, upside down in the foot well.

I know now that auto electrical mechanic is not the job for me