horn sounding on its own

Hi All, While at work on Monday I got a call from reception saying that my alarm was going off. I went out and all was silent, no indicator flashing so just unlocked, locked and went back to my desk. No one at work would no it was mine (daily driver is a company volvo) except for one engineering colleague (who also happens to have a 930 turbo in his garage awaiting restoration) so I messaged him. He said it didn't sound like a normal alarm sound, more like the horn sounding intermittently over a short period and then sounding continuously for a while before going silent. Since having the car I have always felt the horn is a bit sensitive, being easy to make it sound unintentionally. I looked at the fuse with the intention of just removing it for now to ensure it didn't happen again and found the fuse wire broken. I put the spare fuse in and couldn't make the horn sound. It had an MOT a few weeks ago so can only assume it worked then. So, whats happened? is there some sort of dodgy connection causing the horn to sound randomly and then the continuous sounding has caused the fuse to blow? if so, I'm guessing I just need a new horn unit, any suggestions for the dodgy connection? many thanks Steff

Your alarm also has a separate horn. Maybe it was that going off.

common problem with the 4 spoke wheel fitted to early 996 https://rennlist.com/forums/996-forum/485918-horn-problem.html https://www.renntech.org/forums/topic/1728-horn-problem/?tab=comments#comment-11274 check these bushes and the horn relay and fuse try hooking the horn directly to 12v to see if its blown, they do rust away the alarm is a siren rather than horn, well my my99 is anyway

The alarm has a siren and a horn. Alarm your car with the boot or centre glovebox open and you'll hear it beep.

ok cool. thanks both

It's the steering wheel, mine started doing the same while stood on the tipec area at last week's Donington Historic. Also does it under hard braking.

I had a similar fault but on my 997, horn went off on its own in the middle of the night! When got to it it had stopped? After that the horn wouldn't work at all, took it OPC and initially it baffled them, they replaced both horns and that cured it. Hope that might be of some use perhaps. ps. The car only had one horn working prior to this, that had been picked up at its last service but I hadn't got around to booking it it as it was sorned over winter, the lone horn worked till it went off on its own then the above.

Do me a favour .. check under the passenger seat ... make sure theres no water bottles or that its wet under there .. if all good then perhaps the horn . steering wheel contact. My reason .. The alarm horn beeps and will do in an alarm trigger which fits the description .. the siren should go off but didnt hence im wondering water ingress to the alarm control unit . It has a horn and a siren for the UK only markets .. horn is fitted to the o/s of the battery and on the brake servo bracket ... its for the CAT rateing at the time .

Thanks all, Will check for water ingress but pretty sure its ok and having now read up on the contacts/steering wheel issue it sounds very likely that's it.

Right chaps, I had this problem. Call from work to say that the horn had been going off all on its own and then stopped. I did the washer repair on the airbag frame last night and replaced the frame, which had blown. Still no horn. The instrument displays dim a little when I press the steering wheel - so there's a load being taken somewhere. Where does the horn relay live - that's my next thing to check. Cheers

I guessed at a 2002 model and the wiring diagrams are below. Relay board is o/s/f and above the fuse board . GP2 .. or any GP on a wiring diagram is an earth point with the number as the location .. an earth basically . Brown wire.

may I throw my two-penneth in? I had a similar problem with mine. The horn would sound under braking and also if you put any slight pressure on the horn. This was much worse in hot weather. It turned out to be the airbag bracket. This has a couple of rubber bushes on it, that you are pressing against when you push the horn. These become worn and, in hot weather, soft, so there is less resistance against the horn. Its is a cheap part and quick fix. Its worth considering. hope this either helps the OP, or someone else with similar problems.

If it's the black standard 4 spoke wheel you've got I've got a known working one under the bed you can have including airbag

Thanks, mines a 1998, I'll have a look. I assume that if I can hear the relay clicking it's ok?

PM sent re wheel.