Help with aftermarket alarm

Post Sat Apr 17, 2021 5:57 pm

Hi zone.

Had the battery disconnected recently while I was sorting out the central locking. Have a new issue now where the alarm isn't being deactivated by the key fob which means it's impossible to switch off for the time being.

Not an issue for me at the moment since I'm doing other work to it, but I was wondering if anyone can suggest a starting point for solving it since I'm having trouble finding info on these.

Appreciate any help.

Post Sat Apr 17, 2021 9:49 pm

Starting point would be to check the battery in the fob.

Post Sun Apr 18, 2021 11:08 am

Brianmoooore wrote: ↑
Sat Apr 17, 2021 9:49 pm
Starting point would be to check the battery in the fob.

Yep, already replaced it. It has a little red light that lights up when the button is pressed, but the alarm still doesn't respond to it.

Post Sun Apr 18, 2021 4:09 pm

Few details on the alarm might help.

Post Mon Apr 19, 2021 7:27 am

That's the issue, I'm assuming it was installed a while ago and I don't really have any information on it.

The only details I have are that the fob is not bmw and the alarm is triggered by turning the key in the ignition.

I'm assuming it'll be a case of digging around under the dash to see how it's wired in?

Post Mon Apr 19, 2021 10:35 am

E30s were available from new with a BMW alarm, or a choice of, IIRC, three BMW approved alarms, so just because the fob doesn't have a BMW logo, doesn't necessarily mean it wasn't fitted by BMW.
The 'correct' place for an E30 alarm controller to be fitted, if not under the bonnet, is behind the removeable panel in the glovebox, but there's no guarantee that's where you'll find it, of course.
A pic. of the fob might help.

Post Mon Apr 19, 2021 7:10 pm

Appreciate the help Brian.

Here's some pictures of the fob, still working the same way as it always has done from what I can see.

Any common spots I should be looking to find the control unit? With the wiring I've seen so far I somehow doubt it'll be a simple job

Post Mon Apr 19, 2021 7:33 pm

Fairly sure I've worked on one of those before, but without the front cover, I can't put a name to it.
If whoever installed it knew what they were doing, the control unit for it will be behind the glovebox panel, where all the wiring it needs to connect to is present. If they didn't know E30s, then check above the panel above the driver's knees for wiring spliced into the loom that comes down from the ignition switch. Pull out the hazard switch as well, and see if that has an extra wire added to it. There's always a fused permanent live to the hazard switch on cars of this era, so, if they don't know where it should be powered from, the uninitiated often connect to here.

Post Tue Apr 20, 2021 7:34 am

Would any of the panels around the dash need to come off or could this all be checked from just looking under?

I'll check the hazard now as well.

Post Tue Apr 20, 2021 10:32 am

Panel behind the glovebox, and the one to the right, comes off easily. Release the straps supporting the glovebox lid, put a cushion on the floor, and let the lid hang down, then remove the turn buckles that hold the panel in place. Panel above driver's knees is also easy to remove, but is fragile, so remove carefully, noting how it fits, especially at the bottom.

Post Tue Apr 20, 2021 6:36 pm

Saw some crimped connectors under the dash so I started there. Assuming this is all alarm related?

Wires seem to lead under the vent.

Just had a closer look and there are three sets of wires. Two black/red leading connected to red and one red connected to a thicker red. All of them lead under the dash.

Post Tue Apr 20, 2021 6:56 pm

Words fail me! What a bloody mess X 10 is as close as I can get.
You'll have to trace that lot back t where it connects to OE wiring, say what it connects to, and hopefully I'll be able to advise as how to remove and reconnect what's essential.
Looks like the controller might be tucked under the centre console.

Post Tue Apr 20, 2021 7:45 pm

Yeah, seems to be all three leading into it. There's also just a capped plug hanging around down there. Don't know if that's to do with it or just happens to be among the other wiring.

Seems strange that two out of the three wires leading under there are the red/black ones. I'll have a dig under the console tomorrow hopefully.

Another thing is that someone's already made a hash of the panel that hides it, two out of three of the trim clips have just been ripped through the panel instead of getting removed.

Post Wed Apr 21, 2021 12:26 pm

Managed to wrestle it out pretty easily. Didn't even need to remove the console fully.

It's a volkswagen/audi unit, code on the front is 998 VAG 155.

I can't express how many wires are just hanging about.

Post Wed Apr 21, 2021 12:37 pm

Interesting spot for the alarm LED indicator.

Post Wed Apr 21, 2021 1:12 pm

Tzantushka wrote: ↑
Wed Apr 21, 2021 12:37 pm
Interesting spot for the alarm LED indicator.

Haha, so that's what it is. I don't remember if it always lit up since it's been so long since I had the alarm activated/primed, but it's been lit up permanently since I had did the wire mod for the central locking. Don't know if it's awoken some kind of alarm gremlin.

Suppose I'll have to look at replacing that tray as well now.

Post Wed Apr 21, 2021 1:22 pm

Making progress! It hasn't been installed to the connection points BMW provided (probably), so your next task is to follow all those wires to where they go and to list the colours (main colour and tracer) of any OE wires they connect to.

Post Thu Apr 22, 2021 12:20 pm

Alright, think I've traced all of it.

There's one wire that leads left through the dash. It goes to a red/black wire that connects to the horn in the bonnet.

There's three wires that lead into the steering column. One is connected into a blue/brown wire, one into a blue/black wire and the last into a 7.5 amp fuse which then goes into a thick red wire.

There's also a wire tied into the cigarette lighter earth.

There's also this wire which escaped from a spade connector going into the cigarette lighter.

IMG_20210422_123527.jpg

Post Thu Apr 22, 2021 12:31 pm

Just came to a realization.

I'm assuming these things which I cut out when I did the headliner have something to do with how the fob interacts with the alarm.

Post Thu Apr 22, 2021 1:47 pm

Thing in your last pic. looks like an ultrasonic transmitter/receiver. Detects movement inside the car in the same way that a bat would.
The red/yellow with the bare end is a 12volt permanent live, which should be connected to the cig. lighter, but that blue crimp connector isn't the one that BMW put there. If there's another wire connected to the red/yellow to the alarm, it's the main power feed, and can be removed.
Forget that - the one connected to the 7.5A fuse is the power feed, so disconnect it.
Blue/brown and blue/black. Sure it's not blue/red and blue/black? These are the indicator wires, that the alarm uses to flash the indicators when you set it. Again, disconnect and make good.
Wire connected to brown by the cig. lighter is earth/0 volts to the alarm. Disconnect.
Keep tracing, especially looking for connections to plain green, green/purple or black/yellow wires. These are the wires that actually stop your car from starting and running. Not all may be used, but there will be two of each that are.
There might also be connections to the central locking, but there are more than one way they might have done this, besides the correct way.

Post Thu Apr 22, 2021 3:25 pm

Alright, I'll get busy with getting them removed.

I think that's it though, there's nothing else leading out aside from those I've mentioned. I've always been able to start the car even with the alarm going so I can't imagine an immobilizer is something they wired in when they installed it.

Nevermind, found the plain green connection. Guessing that goes as well?

Post Thu Apr 22, 2021 6:02 pm

Got it all out and buttoned up. Jumped it to see if it would run, which it did luckily. Suppose that means replacing the cat is next.

Really appreciate the help Brian.

Post Thu Apr 22, 2021 6:26 pm

Grepot wrote: ↑
Thu Apr 22, 2021 6:02 pm
Really appreciate the help Brian.

I have never come across anything this guy has not had an answer for or more often than not sorted !!!!

Mart.

Post Thu Apr 22, 2021 7:17 pm

Never come across an alarm that was only an alarm before! Assumed it was an immobiliser as well, and that the car wouldn't start.
Green wire connection was probably to stop the alarm going off while driving, if the fob button was accidently pushed.

Post Thu Apr 22, 2021 9:34 pm

martauto wrote: ↑
Thu Apr 22, 2021 6:26 pm

I have never come across anything this guy has not had an answer for or more often than not sorted !!!!

Mart.

Feels like it's more his project than mine at this point lol.

Brianmoooore wrote: ↑
Thu Apr 22, 2021 7:17 pm
Never come across an alarm that was only an alarm before! Assumed it was an immobiliser as well, and that the car wouldn't start.
Green wire connection was probably to stop the alarm going off while driving, if the fob button was accidently pushed.

I imagine it's something the controller would've supported but it just wasn't wired in. With the amount of terminated connections coming out of it I would assume it was second hand out of another car.