Defender horn voltage drop!

Dcoximus · Oct 23, 2017

As it says - I can measure 12v at the earth and power wire to the horn, but when connected it produces a dull almost inaudiable noise and measures 6v,
I've tried replacing the horn and have had no joy,
What could be causing this?
Their is power at the switch in the cab, and it reads 12v complete.

neilly · Oct 23, 2017

I fitted a new horn the other week, old one died due to being sunk in mud and water.

it did the same thing, just a faint "parp". Worked when directly connected to a battery, So I fitted a relay and ran a larger gauge wire to the new horn .

Cheers

Dcoximus · Oct 23, 2017

Thanks - so your saying its likely to be the wire not up to the task? Id rather keep it simple and avoid a relay as electrics are far from my strong point.

Could it be anything else?

neilly · Oct 23, 2017

You can go thru all the wiring and check to make sure all the earths and live wires are good , earth connection is good and clean.
Does the horn work well if connected straight to the battery?
I suspect the aftermarket horns on mine required more oomph than the old one did, certainly a lot louder now. Which is why I fitted a relay.

Cheers

Dcoximus · Oct 23, 2017

Ta - cut the wire and put new ends on and it has more oopmh and will try a whole new wire in the morning!

nobber · Oct 23, 2017

Poor connections can show good voltage but when something draws a few amps through them they can let go.

discomania · Oct 24, 2017

Dcoximus said:
As it says - I can measure 12v at the earth and power wire to the horn, but when connected it produces a dull almost inaudiable noise and measures 6v,
I've tried replacing the horn and have had no joy,
What could be causing this?
Their is power at the switch in the cab, and it reads 12v complete.

Seeing 12V with no load is one thing but 12V and a load can drag it down if there are bad connections.

It could be a corroded terminal, it could be a corroded plug it may even be the switch, but basically under load something is acting like a resistor.

Recently I helped a friend fix some brake lights on a Moke, everything "looked" good and the meter showed 12V to the brake lights, but nothing lit up!

New supply to the brake light switch and all was well, the original feed showed 12V but you could deck it to the block and nothing would happen, not even a spark.

Dcoximus · Oct 31, 2017

Thanks for these - got the horn working, but Now I have a new problem! (Have created a new thread) bum!

Defender horn voltage drop!

Dcoximus

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neilly

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Dcoximus

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neilly

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Dcoximus

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nobber

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discomania

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Dcoximus

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