Horn only works when ignition off

[pj_sibley]

As above, slightly strange issue where the horn only works when the ignition is off. Passed an MoT a few month back, so not sure what's happened since then. Occasionally get one 'beep' out of the horn whilst ignition on, then nothing more.

Any suggestions for sorting this?

 

[cod3oz]

loose earth or live ?? sounds like the ignition is actually shorting the horn out ... only other thing would be to track the wiring to the horn behind the d/s wheel arch (i think)

 

[pj_sibley]

@cod3oz, thanks for your reply. Sounds like I need to pop the airbag out and check the wiring underneath then. It's a strange issue!

 

[pj_sibley]

Horn isn't working at all any more, balls!! Better get investigating.

 

[pj_sibley]

Finally got around to popping off the airbag and taking a look underneath. Noticed that that the cruise/limiter isn't working either, so suspect a problem with the wiring.
Nothing untoward under the airbag, all wiring as it should be and connectors in place.
Any suggestions on what to check next, even if only to rule out things?

 

[pj_sibley]

Further to the above, it turns out that the cruise actually works fine, so it's just the horn that's not working.
I'm thinking fuse or the horn unit itself - hammer time?!

 

[MicKPM]

Remove the passenger front arch liner. Disconnect the horn and using a volt meter, check for the presence of 12v when the horn is activated.

This will tell you where the fault lays.


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[pj_sibley]

Remove the passenger front arch liner. Disconnect the horn and using a volt meter, check for the presence of 12v when the horn is activated.

This will tell you where the fault lays.

Nice one, thanks! Will definitely give this a go.

 

[Mr Plums]

Unbolt your horn from the passenger front arch(13mm socket iirc) take the horn out and see if its got water in it.

When mine stopped working it had water in it, drained it out and left it to dry and it worked fine after.

 

[pj_sibley]

All fixed now...the culprit was a really badly corroded spade connector at the horn end of things. Ended up cutting the feed wire and mounting a new spade connector. Works a treat now, both wheel buttons fine and with ignition on/off. Happy days!