Hi
I have a defender 90 53 reg and i am looking for some help.
The horn randomly started to go off and would not stop whether the engine was turned on/ off or you drove it or not.
After 15 minutes of the horn blaring on and off it stopped.
we have now removed 2 fuses with photos of a horn on them for the time being and I'm hoping this will stop the noise from re occurring in the meantime. (Car is parked right near mine and next doors house so its not ideal on new years eve!)

Has anyone had this before and know what could be triggering it? Will the removal of the fuses be a short term fix that should work?

thanks and happy new year to all!

Could be a short circuit in the horn button or associated wiring. Removing the fuse should keep it quiet, if you are not handy with a test meter, you probably need to get an auto electrician to sort it. The only time my horn sounds is during the mot test, so you probably wont miss it.

Col

are you referring to the alarm back-up sounder going off and is the immobilizer light on when its decides to go off
i would check your passive's (if fitted)for water ingress with all the heavy rain we have been enduring and make sure the bonnet switch is made when bonnet closed

Yes, sounds very much like the alarm to me. The standard alarm used the horns, rather than having its own bleeper. In addition to mystery's suggestions I've had problems as a result of difficulties in the interior light wiring. It's chafed through in places and with the addition of a little rain water ingress can make the interior lights come on at odd times and make the alarm sound if it has been set. In addition I've had the alarm/immobilizer unit (it's in a green plastic box that usually lives behind the instrument cluster) fail on me, but this simply stopped working rather than sounded the horn.

I'm not saying it's definitely any of this, just things that you might want to explore based ion firsthand experience.

The bonnet alarm switch is the most likely suspect, my defender and my next doors range rover have had this, ensure the alarm switch on bulkhead is straight and being pushed down when bonnet is closed, the rubber cover on the switch maybe split, mine was and I fixed it with super glue,

Scooby22 said:

The bonnet alarm switch is the most likely suspect, my defender and my next doors range rover have had this, ensure the alarm switch on bulkhead is straight and being pushed down when bonnet is closed, the rubber cover on the switch maybe split, mine was and I fixed it with super glue,

Click to expand...

Had this on my Disco 300TDi too ...