horn.. does it ever go wrong?

[james.ed]

my horns alway been alittle slow on the uptake. i'd hit the button and nothing, then a beep... but it's always managed a beep. now its gone very quiet and as much as i thump no noise.

I've had the button out, but i was alittle confused what i was looking at! i thought i'd be able to short the wire (by passing the button) to see if that's the problem, but the button seems wireless! is the steering nut and the spring in the middle anything to do with it perhaps?

also.. i've had a spark off one of the wires from the horn when i was checking the spade connections (the one furtherst from the supporting clamp). guessing that means power! as there's two wires into the horn, i'm assuming one is live from the battery, and one is a return via the steering wheel button. if thats right.. which spade connection on the horn should i short to the body to check the horns working?

if that works it'll be the switch or the wire.. any tips on tracing the fault / known problems?

sorry for the ramble.. didn't want to be fiddling without an idea of whats going where! its a 1969 saloon morris 1000 if that helps.

thanks

[Alec]

Hello james,

you have the circuit correct, the horn is fed from one of the fuses and is live all the time, purple wire, the switch wire from the horn to the push button is purple\black. Short that terminal to a good earth and if the power is there and the horn is serviceable it will sound. Common problems are simply poor connections at the horn or the earth to the body.

Alec

[bmcecosse]

The purple wire is the live - the black/purple is the earth return through the horn push.

[phurn]

ive had horns failike that before, but it could just as easy be a bad earth, best bet is place a wire from the negative terminal to an earth ooint, if the horn works then its bad wires, if its still pathetic then its the horn

[james.ed]

quick test has revealed that my horn is not only alive and kicking but is also deafening if sounded whilst the owners head is buried in the bonnet.. should have seen that coming!

so now i know the circuits good from the battery to the horn, the fault must be on the wire to the wheel, the spade with the horn/button, or the button itself. how can i short the circuit at the button end. i don't quite understand which bits on the wheel are live and the earth.. and surely a wire must come into the switch bit somewhere. at the moment i can just pop it out with a screwdriver. i'll also check the spade as they look quite old, but i've given them a fair bit of wiggling so i can't imagine that's the fault (easy to check in daylight with a piece of flex).

[chrisryder]

there will be a brass dot in the middle of the horn put which, when the push is fitted in the wheel, will be held against the wire in the centre using that spring in the column to keep the wire pushed up to it firmly. when you press the horn push, it pushes a contact onto the other side of that brass dot, and earths through to the wheel, and down the column. it could be a bit of corrosion on the brass dot (either side) or on the end of the wire in the steering column (it's just a bullet held into the spring with a circlip. alternatively the button could be struggling to make contact with the steerin wheel. have a look at your horn push and see where the contact is that touches the wheel body, and make sure the contact and the body of the wheel (where it touches) are both nice and shiny. failing that you may need to dismantle the horn push itself. not sure how easy that is, but if it all goes wrong you can get new ones!

[james.ed]

thanks for the explanation.. should i be able to see the sire in the middle of the spring? if so i don't think i can.. perhaps its slipped. i'll have to investigate tomorrow. I need my horn to ward off badgers and white vans!

[chrisryder]

the wire isnt always obvious, but should definately be noticeable if you squash the spring (without covering the centre to allow the wire to appear). i can't imagine where the wire would've gone!

[mike.perry]

Try undoing the steering wheel nut with a socket and removing the steering wheel without removing the fuse. That is a guaranteed method of testing the horn

[Alec]

Hello James,

the wire runs up the steering column and ends in a round contact so it could be the wire is not visible. The other thing, I think, there should be a sllip ring and brush on the column, possibly under the indicator switch cover, if that isn't making good contact then the horn won't work properly.

Alec

[james.ed]

here's a photo of the spring with a screwdriver pushing downwards.. does this look about right?

sadly, even when shorted with a screwdriver, there's no honk in my horn. even sanded the contacts for a conductive shine. guess thats got the switch off the hook. if the spring but looks good i'll start hunting for a loss connection. The cable's pretty chopped and blocked so perhaps one of these has come free.[frame][/frame]

[Alec]

Hello James,

that's it, so there's a break between that contact and the horn. Start hunting for a purple black comming out of the loom near the steering column. As I said, I think there has to be a rotary connector on the column, that would be my first check? (Otherwise the cable in the column will continually be twisted which woyldn't last long?)

Alec