Give me the horn (Help - auto electricians?)

[ferrisbueller]

My horn isn't working. Car was fitted with air-horns at time of purchase and the compressor is knackered. Just replaced it with a generic horn and that's not working either.

When I press the horn I can hear the relay operated (also swapped it out just to be sure) and I measure a voltage across the connectors for the horn so the fuse isn't blown. However, I'm apparently only getting 1 volt.

Any ideas please?

Edited by ferrisbueller on Saturday 24th July 13:18

[Plotloss]

Is the relay arse about face?

[ferrisbueller]

Plotloss said:

Is the relay arse about face?

Nope.

[Pigeon]

Bad connection somewhere. You should be able to light a bulb from the positive horn connector to earth and also from battery positive to the negative horn connector. The connector that doesn't do this is the one with the bad connection somewhere in its wiring.

[ferrisbueller]

Pigeon said:

Bad connection somewhere. You should be able to light a bulb from the positive horn connector to earth and also from battery positive to the negative horn connector. The connector that doesn't do this is the one with the bad connection somewhere in its wiring.

Is this with the horn button depressed?

It's not an easy check as the battery is in the boot......

[netherfield]

If you can see the starter motor,the biggest cable is positive straight from the battery.

And many cars with the battery in the boot have a positive connection in the engine bay for jumper cable use.

Edited by netherfield on Saturday 24th July 13:44

[Pigeon]

ferrisbueller said:

Is this with the horn button depressed?

Yes... gaffer tape may be useful

ferrisbueller said:

It's not an easy check as the battery is in the boot......

Long piece of wire may also be useful

[spikeyhead]

if you're getting 1V across the horn, then either it's close to a short circuit or else the voltage is getting dropped elsewhere. Try the horn separately with some jump leads.

If it's ok with that, then it's probably a poor relay or a bad earth. My money is almost always on a bad earth.

[ferrisbueller]

A combination of several of the things above. Sorted. Thanks chaps.