Alarm woes

[Alluminio]

Two nights ago (why do alarms always give grief in the early hours...) the alarm on my 2001 A8 4.2 FL began to act-up.

The car was locked in the usual manner and some time later the alarm began emitting, continuously, three loud beeps, followed by a pause, then three loud beeps. The volume of the beeps was the same as when the alarm is triggered, but it was not accompanied by flashing indicators.

All windows, doors and the boot lid we securely shut.

I left the car unlocked as this was the only means to silence it.

Yesterday, the car appeared to be OK, until 1:30 AM this morning when the repetitive alarm beeps began again... so the car was once more left unlocked.

Having searched the forum, I had assumed the problem would be the back-up batteries in the alarm horn, but on reading the numerous posts on the subject, it was my understanding only three beeps were heard when the car was unlocked or started, as a signal the alarm batteries were on the way out. Not a continuous three-beeping with the car locked.

It might be coincidental, but button 1 on the driver's seat memory is now inoperative...

Is the alarm beeping I have described the back-up batteries? If so, would someone point me to a thread which shows the location of the unit with batteries.

The part number of the replacement unit would would be very useful too, just in case time constraints mean I can't embark on a Dremmeling adventure!

TIA

Mark

[The_Laird]

Part number 8L0 951 605A. The unit you remove will be without the 'A' suffix, but apparently this part number is the 'new and improved' version.

Location - there's a photo in a thread on here if you search (I'll see if I can find it and post a link) - but it's above the central locking pump on the left side of the boot. You need to remove the plastic trim at the rear edge of the boot (where the light and load securing handles are) and the trim on the left side. Then remove the CD changer and the plate it sits on (you don't need to unplug it, just move it out of the way.

You can then pull out the side felt-like trim enought to get at the alarm horn. It's right at the top, secured by a single captive bolt. It's a tight fit and the electrical plug wiring is short - just to make it awkward! A small screwdriver is needed to release the 'lock' on the plug.

There you go. Good luck!

Edit: here's the thread http://forum.a8parts.co.uk/showthread.php?t=8536

[David's8]

There are a lot of us who have had issues with this damn alarm horn! (as you can no doubt see from the threads!) but your issue is a strange one. The only thing that I can think of regarding the peculiar timing (middle of the night) is that batteries perform less well in the cold and the overnight temperature drop causes the standby batteries voltage to initiate a low voltage warning. But why it should keep up the pattern of beeps is beyond me. However, on the positive side its good that you get a loud beep out of your as mine sounds more like a trapped mouse on the boot.

[HPsauce]

As one of the later contributors to that thread I would concur that the warnings occur (randomly, never every time for me) shortly after turning the ignition on.
Doing it at other times would suggest something else may be going on with the locking system, or possibly just the electronics inside the horn are damaged by the leaking batteries?

[Alluminio]

Many thanks for the replies.

I have elected to buy a new part; £119.15 inc VAT from my local dealer. It's surprisingly inexpensive compared to the prices of parts I pay for my other 'classic' - a Generation 1 Honda Insight.

I will post the outcome once the new horn has been installed.

Next problem to sort... squeaking rear suspension!

[Alluminio]

Sorted. And another 5-star review for this excellent forum!

The interior of the boot came to pieces easily and the most difficult job was removing the connector from the alarm horn. Once removed, the new horn - which is smaller than the original - was easy to install.

It took c. 30 minutes from start-to-finish to undertake the task. The longest part was removing the connector.

Once installed, I triggered the alarm deliberately and the sound from the horn is most certainly limp-wristed...

The car is now locked and thus far, no beeping from the alarm.

I took a hammer to the old alarm unit (made in Australia, whereas the new one is made in Hungary) and sure enough the Ni-Mh batteries had leaked onto the PCB and corroded the contacts.

Once again, many thanks for the information.

[The_Laird]

I'm a sucker for a happy ending!

[David's8]

Originally Posted by Alluminio

.......the sound from the horn is most certainly limp-wristed...

I took a hammer to the old alarm unit ........

I still cant understand why the alarm horn should be so weak. And this is a new one! I still believe that mine is lacking the amplification part of the circuit but from what you say I shouldnt expect much from a new unit.

Glad to see you employed a forensic approach to fault finding

[The_Laird]

Well, I got mine sorted, but what a pig!

As the Passat alarm horn didn't work, I splashed out on 8L0 951 605A from a breakers (with a 3 month gurantee). Stripped out all the 'stuff', plugged it in and - not a peep!

Further investigation (and investigation in that space is no joke) revealed that the corrosion on the original alarm horn pin had spread to one of the contacts in the plug. The corroded contact had expanded and split the plastic surround, so when the horn pin was pushed in to the plug, the contact just moved backwards and no electrical connection was made.

Well, after a couple of proclamations such as "gosh" and "goodness me" (or words to that effect), I came upon a solution.

For some reason I had kept a few bits of wire from when I was messing around with the front fog lights, and one bit had a connector that fitted the plug contact (now removed from the back of the plug) just right. So, I stripped the wire from the other end, pushed it through the back of the plug and bent it over so that it wouldn't come out.

Then I pushed the connector on the other end onto the free contact, plugged in the horn and tested it. Bingo!

Just one issue though - I still don't know if the Passat horn would have worked - but David has that now and no doubt report when he's tried it.

[steamship]

Originally Posted by The_Laird

Further investigation (and investigation in that space is no joke) revealed that the corrosion on the original alarm horn pin had spread to one of the contacts in the plug.

Exactly what happened with mine. Since I knew about the plug corrosion, when I sourced mine from an 05 A4, I took about a foot of cable with it.