How does the horn work (wiring wise)

[pow]

Hi,

I'm normally fairly good with automotive electrics but I'm stumped on the horn in my early bay. The horn has two wires going to it, looking at the wiring digram one comes from +12v and one goes to the wire that pokes out the middle of my steering wheel (that should have the horn push attached to it). So, logic tells me that to complete the circuit (Beep beep) the horn push (when connected to said wire and pushed down) completes the circuit by earthing the brown wire.

But, what I don't understand is when I do a continuity test on that brown wire poking out the steering wheel to earth (some metal inside the steering wheel for example, or anything unpainted on the van) I get continuity - the brown wire and the vans earth are constantly connected?

Is that right? I don't get it if it is the case! Can someone explain this to me please?

Thanks

 

[67panel]

thats cos the outer of the steering column is "live"from the horn ,the brown is conected permantly to earth throgh the steering box .

 

[pow]

Ooo I see I think, so the wire poking out the middle of the wheel is a permanent earth?

So as I have a new wiring loom, where does the horn to outer steering column connect?

 

[gagvanman]

I have to say I am confused that anyone would say that the steering column would be live. Even with only 12v this is going to cause some suprises, and some blown fuses.

The live should go direct to one side of the horn and the other side of the horn is fed up through the center of the steering column to the button on the steering wheel where it is earthed when the horn button is pressed this completes the circuit.

I think the confusuion comes from the fact that the steering column is isolated from earth normally and a special contact within the column connects it to the body. In my case a washer welded to the outside of the column.

 

[bigdaz]

The principal was that the horn has the live feed to it and operates when earthed by the other wire that runs up through the column. The problem is the wire usually wears and shorts in the column causing the horn to go off on its own so someone might of disconnected it at some time. It connects through the steering coupling.

 

[pow]

So mine is deffo broken, the wire down the middle of the column is touching earth all the time, is it easy to fix?

 

[tomedwar72]

This might help:

http://www.type2.com/library/electris/sterhor1.htm

 

[pow]

Well that looks annoying :lol:

 

[67panel]

Was trying to make it simple to understand. :roll: when I said column was"live"from horn its feed with a ign feed to the horn (same feed as brake lights)then the wire goes from the other side of the horn to the steering column that is insulated by plastic and rubber from earthing out .when you press the horn push it conects to the wire that runs down centre to earth.the wire that comes from the horn is conected to a spade terminal riveted to the bottom of steering column tube .only way to see it is raise column outer up and that means taking the steering wheel of.