DIY Solutions

[IchBautAuto]

Flash as a rat with a gold tooth. If only I had a phone that took the App. Can't see why a range extender wouldn't work.

[IchBautAuto]

Waiting...waiting for the post to deliver the new P3 gauges analogue control unit. While so, I have the same issue as many with the center front arm rest lid catch, broken. I understand that a repair kit is available but if it is anywhere near as fragile as the original I can't see the point. I tried using magnets and while the idea is sound, the execution lacks a little in providing the sideways location that the original catch does.

In the end I made up a new bracket in aluminum. It fits perfectly to the thou, works a treat and is invisible when the catch is fitted. It should also last a damn sight longer. The tape is 3M for bonding metal to metal and it is permanent.

One more little job out of the way.

[IchBautAuto]

Moving along, with the enforced idleness, been a week since I drove and the battery voltage was down a lot again. The alarm horn still worked, chirped on lock etc. I've removed it and just left the plug loose. Now to see if it makes any difference. So easy in the Saloon, 2 minute job and it's out.

Had to drive this morning and other than no chirp, nothing indicates the horn has been removed. I have yet to do a VCDS scan so expecting a fault code. As a quickie, is there anything I should do / have done after removing the horn or is the general approach to replace it? I don't have any issues with having no alarm horn so that would be no reason to replace it. As an aside, the Alarm horn is made in Australia by Bosch. Fancy that. Genuine 8L0 951 605A. Badged with VW, AUDI, 906 and Bosch. I haven't done a thing with the horn assembly yet, Looks absolutely brand new but have yet to check the voltage.

[Shoppinit]

I thought the horn would sound if you disconnect it. Interesting that it was made in Australia. Last one I bought was made in Hungary (IIRC). They are junk anyway. Even when they go off it sounds like someone's 80's digital watch alarm going off 6ft away.

[IchBautAuto]

The made in Australia seems common, when I was looking at some US sites their pictures showed the same. Practically, there has been no difference to the car other than the chirp when locking has gone. I'm cutting it up today to check the insides. I did a quick voltage check across the alarm horn terminals and the voltage shown was 6.7V whereas it should be about 13.7v with new button cells. There may be some circuitry influence on the voltage or not, no idea but while it looks brand new, it is likely original.

Plenty of time now to work out what I might replace it with, or not.

[IchBautAuto]

Further to my earlier post and with all the spare "isolation" time, I've got myself a little educated on the Alarm horn. Firstly, the fitted batteries are Varta 2x3.6v V150H rechargeable cells, which, as said elsewhere, are no longer available. There are alternatives however so a repair is not out of the question.

My first mistake was thinking that the alarm battery would be a nominal 12v as it is charged by the car system. It is actually 7.2v and I haven't spent any time on working out how it is charged and the voltage modified. I did find the spec sheet and Varta's published lifespan is 6 years trickle charging at 20 deg C or 3 years trickle charging at 45 deg C. Based on that, a max of 6 years and it is on borrowed time. So after 16 years it's done well.

The horn I removed is date stamped 2003. The circuit board is actually unmarked and there is no corrosion to be seen. This horn did chirp on door locking but voltage across the battery is 6.7v and as it was removed after a few hours on charge it would seem that a / the cells are fubar anyway. The horn has only been out two days so I'm waiting a little longer to see if there is any appreciable voltage drop but normally a week would take the (new) start battery down to about 12v so there was some serious parasitic load somewhere.

While the horn seems to have a number of minor functions, there doesn't seem to be any adverse effects by removing it, other than the bleeding obvious of no chirps.

Maybe more to come once I get a little better informed.

[Shoppinit]

I’m still surprised that it doesn’t go off on disconnection. I’ll have to look into it.

[Mɐʇʇ]

I'm interested in this - I have a spare in store and planned to revamp similar to you.

As it is the car's still parked up in the garage after all that work.

[IchBautAuto]

I’m still surprised that it doesn’t go off on disconnection. I’ll have to look into it.

I was half expecting that but zero. To all intents it seemed to be working when I removed it. Always gave a solid chirp when the doors were locked and the only reason I took it out was to work through the power drain issues. Small things that came up during this process include when I open the boot lid, the CTEK battery charge point which has an LED charge indicator switched from green to amber (12.57v measured) and once the boot light had extinguished, about 10 mins, the light went back to flashing green. Clearly there is enough of a current drain from the light system to drop the battery voltage below the set point on the charge socket. Considering that this should be a reasonably low watt bulb, it might be another area to investigate as a single bulb really shouldn't noticeably drop the voltage of a new 110 AH battery.

[Shoppinit]

It doesn’t take much for the ctek to kick in though. Mine will go from green to orange if I open a door. Might be a red herring. Still, easy enough to check.

[Shoppinit]

Can't find any information about the alarm horn sounding when you disconnect it. I guess the batteries are there so that it continues to sound if you disconnect it once it's been triggered.

Have you measured the total current drain an hour after locking the car? I can't remember if you told us or not.

[IchBautAuto]

I've checked the festoon lights both 5w and no obvious defects. Car is still on green on the CTEK after 3 days and the battery still over 12.6v and the current draw when measured was negligible. The previous reading was 0.2 amp after an hour. My next check will be to measure the battery after the car has been locked for a few days to see if the voltage drop appears when the immobiliser system is engaged. Certainly the massive battery drain is not present now if the car is unlocked.

Re the alarm sounding if unplugged, it doesn't happen when the car battery is disconnected which would sound more likely to happen but anyway, it was working before, so if it should have done so it was in working order.

As an aside I thought I'd check out the B5 RS4 alarm siren / horn. The parts book shows the same unit as fitted to the RS6. As it turns out, that is only in GB, the actual horn fitted is the Anti-Theft Alarm Horn / Siren 4A0951113. That goes back to the 1992 quattro and up to the 99 A8 & S6. No fitted battery here, just a horn. And for a change, the RS6 was far easier to access.

[IchBautAuto]

OK, check charged the battery, locked the car and opened up 4 days later. This test done earlier with the car left unlocked had the battery at 12.57v after 4 days. With the alarm/ immobliser system activated the battery voltage was 12.48v after the same 96 hours. Rough calcs after the 4 days had the battery at 90% unlocked and about 82% locked with the added immobliser current draw. Considering the range of (old) electronics, that doesn't sound like a big issue to me.

Before I removed the alarm siren, the battery would drop to 12.28v after 6 days (60%) so it may still not be perfect but it's a big part of the way there.

There was an old fault too, supporting the alarm horn theory.
1 Fault Found:
01134 - Alarm Horn (H12)
76-10 - Terminal 30 missing - Intermittent

Thanks to Shop for mentioning the potential cause. Saved a pile of extra work.