Headlights and Horn

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Jasper
Posts: 53
Joined: Wed Jul 21, 2021 9:30 am
Location: Hailsham East Sussex

Headlights and Horn

Post by Jasper » Wed Dec 22, 2021 5:18 pm

Hi
Can anyone tell me why, when headlights are on, the horn will not sound

Kind regards

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peter_winney
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Location: BATH

Re: Headlights and Horn

Post by peter_winney » Thu Dec 23, 2021 12:23 pm

Jasper
That's a new one for me! Might be a wiring or earth problem. Or perhaps low battery and charging system not working. Does revving the engine to increase the charging make any difference?
Peter W
Member since July 1972
I ache, therefore I am

Jasper
Posts: 53
Joined: Wed Jul 21, 2021 9:30 am
Location: Hailsham East Sussex

Re: Headlights and Horn

Post by Jasper » Thu Dec 23, 2021 12:30 pm

Peter

No it doesnt!!
Regards

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peter_winney
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Re: Headlights and Horn

Post by peter_winney » Thu Dec 23, 2021 12:42 pm

Does the horn sound when the headlights are off?
If you "hotwire" the horn with the headlight on does it sound?
Member since July 1972
I ache, therefore I am

Jasper
Posts: 53
Joined: Wed Jul 21, 2021 9:30 am
Location: Hailsham East Sussex

Re: Headlights and Horn

Post by Jasper » Tue Dec 28, 2021 12:18 pm

Hi
Yes, the horn sounds with no lghs on and sidelights on. Turn the headlights on and the horn does not work

Many thanks Peter

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peter_winney
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Re: Headlights and Horn

Post by peter_winney » Tue Dec 28, 2021 6:22 pm

I would be willing to bet you have a 6v car ;)

Seems to me likely old wiring and poor earth return creating too much resistance in the electrical circuit to power both at the same time. You can check circuits are OK using a multi-meter but others are better able to advise on that - I am not expert. Suggest first clean up all earth contacts on horn and lights and check that there are also clean and firm connections in the wring, and that there are no visible splits or frays in wires.

For headlights I fitted an earth return back to a point on the chassis and do not rely on earthing only through the wing bolts.

Horn differs from most other electrics on the car by having the operating switch after the item in the circuit and not before - it works by earthing back to the button on the steering - i.e. live wire to the horn (which is why it has an insulated bracket).
Member since July 1972
I ache, therefore I am

Jasper
Posts: 53
Joined: Wed Jul 21, 2021 9:30 am
Location: Hailsham East Sussex

Re: Headlights and Horn

Post by Jasper » Wed Dec 29, 2021 9:22 am

Peter
Thank you so much for advice...will have a go when the weather dries up a bit

Best wishes

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