Horn wiring

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nwxh
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Horn wiring

Post by nwxh »

The forum has been very useful about how the horn works however looking at previous topics, there seems to be contradiction about whether the metal shoe on the indicator stalk (and the rest of the metal and wire) is always connected to the horn or the earth.

In addition, should the metal point which the horn button pushes on, which comes out of the middle of the plastic insulator, be always connected to earth?

I have also seen different information about whether there is a wire to the steering column which does not go to the assembly or if the horn button simply earths via steering column and car body. Perhaps there are actually two shoes and slip rings?

In my case, the horn has gone from always sounding (had to open bonnet and disconnect) to not sounding at all (hope it didn't break after being on for so long). However, the shoe is currently always earthed.

So far I took off the steering wheel and one plastic casing. I guess I could go further if required to see wiring.

Thanks for all the help.
MCYorks
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Re: Horn wiring

Post by MCYorks »

If I recall correctly, the earth return from the horn (purple wire with black tracer) connects to the metal shoe on the indicator stalk and so to the metal slip ring and wire in the centre of the insulator. So the metal point which the horn button pushes on, and which comes out of the middle of the plastic insulator, should normally be insulated from earth. This point is only connected to earth via the steering column and body when the horn button is pushed, thus completing the circuit and sounding the horn.
Hope that all makes sense.
ManyMinors
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Re: Horn wiring

Post by ManyMinors »

The explanation above is correct. The horn itself has a permanent live feed from the fusebox and pressing the horn button completes the earth. To test the working of the horn itself - assuming the fuse hasn't blown(?) and you actually do have a live supply, then simply run a temporary earth cable from the other connection on the horn to the car body and the horn should sound.
nwxh
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Location: Bath, UK
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Re: Horn wiring

Post by nwxh »

Many thanks, it's fixed now. I think it was a stray strand earthing the brown ( :-? ) wire connecting the shoe. Strangely, I got a continuity test to earth but the horn was not sounding continuously like it was when I had to disconnect, so I guess it became a higher resistance connection. It was confusing me last night how the slip ring on the outside of the steering column could connect to the inside, but I guess there is a hole in the side of steering column under the slip ring and plastic cover. (Does anyone have a nice picture?)

I think everyone may have been actually saying the same thing by different names, but I was confused as to whether the shoe should be always earthed or if this was the fault. But for avoidance of doubt, I think this is correct from what people have written and my experiments today (please correct if wrong):

At the steering wheel, the "live" side is actually on the earth side of the horn when the horn button is pressed. But it will be battery voltage until the horn is pressed and so insulated. The wire from the horn connects to an insulated piece of metal on the indicator stalk, which has a shoe which always connects to the slip ring on the steering column. This then connects to a solid but a but slightly flexible metal wire (more like a thin nail) which goes inside the centre of the steering column and to the finger at the very front of the steering wheel which is in the centre of the horn push.

The finger like the shoe is always "live" but shorting it to earth sounds the horn. It is not pushing the finger (despite it being springy) that shorts the earth sounds the horn but rather the horn push button. This button connects the always "live" finger to the metal on the steering wheel, which is connected to earth via the steering column and the rest of the steering assembly.
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