Horn Sounding By Itself

[Moto61]

Just wondering if anyone else has experienced this Alfa 'feature'....Alfa 159 3.2 Q4 auto

When I turned the engine off after a drive on Friday the horn started blaring immediately. It wouldn't stop even after locking the car, but would stop as soon as I restarted the engine. When I stopped the engine, the horn started again. I ended up pulling the horn fuse to get it to stop.

When I got back home I disconnected the battery, reinserted the fuse, and all good - no horn. I locked the car, went inside and 10 mins later, the bloody horn starts again! I've pulled the fuse again to avoid annoying the neighbours with random horn events...

Anyone come across this before, or have any ideas?

[bazzbazz]

Whats the voltage on the battery when standing still & engine off?

[Moto61]

Whats the voltage on the battery when standing still & engine off?

I will check but the battery is only a couple of months old (and charging system was checked when the battery was replaced), and I'd just been for a long drive. 

[Alfa-mad]

Whats the voltage on the battery when standing still & engine off?

I will check but the battery is only a couple of months old (and charging system was checked when the battery was replaced), and I'd just been for a long drive.

Could be the horn relay on its way out.

Swap the horn relay with the relay for the main headlights (same type relay) and see if the behaviour is fixed. If it works like normal with the relay from the headlights, then you know to buy a new one.

[MD]

Alternators have a nasty habit of being perfect one day and outta gogo juice the next. If the brushes are marginal it may develop intermittent charging  symptoms. Nevertheless, as bazz has suggested possibly a low voltage may trip it.(My assumption) Then again a low voltage would give other problems like starting issues so perhaps one of your security inputs is failing to provide the input to the security module?
Failing that, it's an emotional problem. Hates being lonely. I wouldn't suggest moving the mattress out into garage to cure the problem.

[Moto61]

Alternators have a nasty habit of being perfect one day and outta gogo juice the next. If the brushes are marginal it may develop intermittent charging  symptoms. Nevertheless, as bazz has suggested possibly a low voltage may trip it.(My assumption) Then again a low voltage would give other problems like starting issues so perhaps one of your security inputs is failing to provide the input to the security module?
Failing that, it's an emotional problem. Hates being lonely. I wouldn't suggest moving the mattress out into garage to cure the problem.

I have had issues from low voltage in the past & that was the reason the battery was replaced, and that certainly involved random warning lights...but I do like your idea of it being an emotional problem . A much more realistic diagnosis for an Alfa! The garage is occupied by an MV Agusta and a Ducati, so the 159 has to slum it outside. Maybe it is sending me a not so subtle message....maybe next thing I know.....a horses head appears in the bed if I don't show it enough amore???