Horn not working

[Midnight]

This has probably been aired many times, but my horn decided to stop working the day before an MOT test!. The relay under the dash is clicking away when I press the horn button but nothing from the horns. I believe the horn circuit is always live with the pressing of the horn button simply completing the earthing of the the circuit. All the terminals have been checked and cleaned and the wiring to the horns is good condition and nothing has been disturbed in the car recently. i did notice that the 20 amp fuse had blown but this migh have been when I was fiddling, as I repalaceD it and it stayed intact afterwards. I've tried swapping the two identical relays on the fuse box as well with no change, Any ideas I could try?

[k80rum]

I'd work backwards from the horns to the problem. So far as I understand it, the horns earth through their mounting points. You could check the horns themselves by removing the spade connector from each and (assuming your battery is earthed to the chassis while you do the test, take a flylead from the +ve to each horn spade connection point in turn.

 

Having established there's no fault there, try a continuity test between the spade connectors at the loom end, and the purple/yellow connection at pin 80 on the horn relay (with the relay removed). Then it'd be a quick check to confirm there's continuity at the relay power (pin 86 with the brown connection) by checking its getting 12v from the battery .

 

Pin 87 (the purple and brown cable I think) at the relay goes to Fuse 11, so this should be providing juice with the ignition on.

 

The last connection - pin 85 on the relay (purple and yellow) will indicate a switch fault. Disconnect at the horn button and earth it to the chassis, with the ignition on. If the horns work then but don't when it's reconnected and the button pressed, it must be a button fault.

 

Hope this helps - good luck with the searching

 

 

 

Darren E

 

Website and Emerald maps library:

K80RUM Superlight R #54

 

 

 

Edited by - k80rum on 30 May 2007 08:59:56

[Midnight]

Hi Darren,

Thanks for the reply. I'll give it a go tonight

[Midnight]

Thanks for the Reply Darren,

I'll check it out tonight.

Des

[Manxseven]

there is an echo in here 😬 😬

 

Caterham Fireblade here