Horn sounding spontaneously

[tom1985]

My 1000 has developed a very annoying (and MOT-unfriendly) habit of sounding its horn by itself!

Before jumping to conclusions about cars having minds of their own, or Stephen King-esque demonic possessions, I think the most likely reason is that it is shorting out somewhere. The horn generally sounds when turning the steering wheel.

I've taken the cover of the centre of the steering wheel, and there doesn't appear to be any problem with the push button, and I cannot see any damage to the wire leading to it. The wire from there goes down inside the steering column. I've got a wiring diagram that shows what it's connected to (the horn is the purple and purple/black wires, apparently) but I don't know where it physically goes.

Has anyone had a similar problem? Is it likely to be a short, and if so, any ideas on where / how I could start looking for it?

Many thanks as always!

[pgp001]

You are probably correct about the wire shorting to earth, that is what happens when you press the button.
I had an intermittent problem with the horn not working at all, it turned out to be a loose bullet on a wire behind the drivers glove box.

If you remove the glovebox you can get to most of the loom htrough there and start checking things out with a meter.

If it is only happeneing when you move the steering wheel then I would remove the column cover from where the indicator stalk protrudes and check what is going on around the slip ring area.

Phil

[simmitc]

Classic symptom of shorting and you've been looking in the most likely area. I had one once that always sounded the horn when turning right or left, but not when going straight. That made it easy to diagnose that the problem was in the steering column but I couldn't see anything obvious so I replaced the entire length of wire and the problem disappeared. An easy check would be to disconnect the wire where it goes into the coilumn - if the problem goes way then that's where the fault lies. It might be the cable but could also be where the contact on the side of the column runs. With the column wire disconnected, if the problem persists then, the short must be elsewhere, so try wiggling the harness around.

[tom1985]

Thanks very much, both. Where exactly does the wire get into the steering column? Is it around the cover where the indicator stalk is, or does it go right through to the base of the steering column?

[tom1985]

I was able to - I think - rectify this problem this evening. There was an exposed bit of wire that was shorting against the inside of the steering column, which I think was the culprit.

It turns out that the supply to the horn push button enters the steering column beneath the indicator stalk area, via a spring-loaded stud that applies against the underside of the brass ring through a hole in the plastic ring beneath it that fits around the steering column (sorry I don't know what these parts are technically referred to). The brass ring has to be slid off to get to it. I hope this helps anyone who might at some point have the same problem as me

[geoberni]

What's weird is that I posted info you asked for, ie where the wire goes into the column, on Monday afternoon including a link to Charles Ware website page, but it's vanished. Perhaps my mistake, or just another forum glitch!

As you have said, the supply wire comes from under the dash to the leaf spring contact against the brass slip ring. The supply then comes up the centre of the column to the sprung contact (9 on illustration) under the horn button. Pushing the horn then shorts it to the return path through the column.
https://www.morrisminor.org.uk/parts/60 ... e-size=all
I've been careful not to use Positive and Negative in that description, as some people are still on Positive Earth systems.