Ticking noise from inside boot
 

Just this afternoon I noticed quite a loud ticking noise coming form inside the boot, around the alarm horn/CD changer area. It’s ticking regularly, with the ignition off, at around once per second, and has been doing so for some hours now. (I don’t use the CD changer, but I do have phone prep, which I think is in that area too).

Hopefully nothing serious as we’re just heading off to Scotland!

Anyone got any ideas? :Confused:

Does your alarm siren still work Jim? If not, might just be the old leaky siren battery problem causing the siren circuit to emit the ticking noise.

I’m not sure if it’s still working. Brian gave me one a year or so ago and it was OK when I fitted it. But I think I’ll take the damn thing out as this is the third that I’ve fitted. Unless anyone has found a lasting solution?

My lasting solution was to take it out and throw it away ;)

Before I copy Brian’s solution, does anyone know if a compatible new alarm horn is available? Preferably one that you can hear clearly!

Not aware of a compatible horn unfortunately, and you're already quite aware of the (continued) issues of replacing them. I replaced mine back in October 2013 with one I had scavenged from an '05 A4, and it still works, but you have to the hearing of a dog to notice it. It seems to lose volume as time goes by, that's assuming the batteries don't get to it first.

If I lock the car standing by the drivers door, I can't even hear the confirmation beep. As for the alarm itself, I just tested it (again from the drivers door) and it is pathetic.

This is the guts of the faulty alarm horn. probably past saving!

Mine is a replacement that I bought some years ago from our sponsors.
It's still fairly "chirpy" but VCDS throws up a "low internal voltage" error and has for ages.
So, some day I'll probably open it up and replace the batteries before it gets that bad!

It's predecessor was the older shape and a real corroded mess inside, though when I cleaned it and replaced the batteries it did actually work.
But it was never great so I decided to fit one of the newer style ones and hope! (The newer shape also has a different mounting bolt so I had to get slightly creative to fix it.)

So, Jim, clean it up and fit new batteries, you never know! +++

You can't go for anything too new though if you do replace them; they look the same (and have very similar part numbers) but there are subtle difference in the wiring and/or communications protocols and despite investigating for ages I never got anywhere.

That must be a newer version from the original fitment, as the PCB is smaller than mine when I pulled it apart, although mine was well past it anyway, as the three connector pins on the PCB were also corroded, as were the pins in the loom connector block.

That might actually be saveable. As long as the PCB tracks are all intact and it hasn't corroded anything else, it may just need a clean-up and a new battery

My original unit was much worse than that; the leaked battery chemicals had eaten part of the adjacent transformer/choke and corroded away numerous PCB tracks.

I have another unit which is in better nick. The batteries have started to corrode, but the circuit board looks not too bad. But where can I get the batteries? The part number throws up a very similar batter, but with only 3 connections instead of four.

Electrically, there will just be the usual 2 (positive and negative) connections on each battery but some have additional pins for better anchorage. Usually any extra pins are connected by a PCB track so it's possible to make a different pin configuration fit with some coper wire and a bit of fettling. It should be possible to find one with the same configuration though. What's the spec' and part number printed on the battery?

There are two batteries marked as follows:

VARTA
2X3.6V 140 mAh
2x3/V150H Ni-MH
103 —>+

TPS will still sell you a newer one of the correct spec, if needed. The sirens are all pathetic - I activated the chirp just so I knew the poxy thing was doing something for the expenditure! You also need a different nut to fit it as the thread is different 🙄

I had to replace the plug and wiring as the corrosion had eaten the pins and plastic - it did make fitting the new siren easier as the OEM wiring is very short!

I'm struggling to find anything quite the same from any of my electronics suppliers. I'm sure that particular battery configuration used to be quite common but it looks like nobody stocks it any more.

I think I would probably just check the dimensions and make my own battery 'pack' instead, using something like this (assuming that has the correct dimensions). You'd need to tape (or, preferably, heatshrink) 2 of those together and solder wires to them instead. Don't solder directly to the battery though; some batteries have been known to explode when exposed to excessive heat from a soldering iron.

Still think you should follow my example +++

I have! :)

I found this battery too, but the pins are the wrong orientation and there should be 2 on each side. I don’t really think I can be bothered with making up a battery pack (I’m not the best with a soldering iron!) and I’m not sure that it would fit into the horn if I did. I think it’s all too much trouble for a feeble chirp that no-one would pay any attention to.

It's potentially a cheap (or chirp) fix, assuming there's no other damage. But I agree, probably not worth the effort.

I cut my old one open too when it failed but that was largely out of curiosity. After determining that it wasn't worth repairing, I swiftly binned it and replaced it. Replacements units were readily available at the time though; I might have been more inclined to persist with the repair if they weren't. In any case, I like chirps; it's a helpful confirmation that all the doors are fully closed and locked as you walk away (since it won't chirp if any are left ajar). So I'd still repair or replace if possible.