Horn goes on randomly when I turn the wheel

Gotta love that wiring . . .
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SouthSwedeSpider

Horn goes on randomly when I turn the wheel

Post by SouthSwedeSpider »

I have a really annoying problem. My horn has starting to take initiatives on its own - when I turn, the horn sometimes goes on just like that, without me touching the horn button. Happened in a parking garage the other day, and I felt really stupid :oops: . I have removed the fuse as a temporary fix, but the same fuse goes to the electronic immobilizer, so I have to put it back every time I start the car, and then remove it again, so it's no long-term solution.

I have removed the horn button, contact and cable looks OK there. I also removed the steering wheel, and I can't see any obvious damage; the two contacts that I assume both should make contact with the brass ring on the back of the wheel are intact. The only thing that bothered me was that it looked like the brass ring in the column (the one with the two contacts) appeared to be very close to (and maybe sometimes in contact with) the steel centre column. If they get in contact, will the circuit be closed and the horn go on?

I'm off for a few days but will post pics when I'm back. Meanwhile, any intelligent thoughts on how to fix the problem are welcome. Otherwise, I will be considered the most aggressive driver in town. :evil:
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manoa matt
Posts: 3442
Joined: Thu Oct 26, 2006 4:28 pm
Your car is a: 1978 Fiat 124 Spider 1800
Location: Honolulu, Hawaii

Re: Horn goes on randomly when I turn the wheel

Post by manoa matt »

The two contacts in the steering column switch assembly should contact the brass outer ring and the steel center ring on the bottom of the steering wheel hub. The horn button connects the two to complete the circuit. Swing one of the contact tabs out of the way, they are both contacting the brass ring.
SouthSwedeSpider

Re: Horn goes on randomly when I turn the wheel

Post by SouthSwedeSpider »

Hooray, problem solved!! Thanks Matt, your input plus an older thread made me localize the problem. I took some pics to show, should anyone else have the same problem.

The inner contact was so worn down that the remaining "hook" on the outer side had started to made contact with the brass ring when turning the wheel. The brass ring was intact (see pics). The problem is probably that the numbers on the steel center ring slowly wear down the much softer brass contact when the wheel is turned.

Image

Image

I just removed the small piece sticking out so that the inner contact once again should make contact with the inner steel ring on the back of the wheel.

Image

Finally I covered it all in dielectric grease, put my fuse back and voila, it worked. Now I can drive and listen to the radio without fearing that my horn will sound in the middle of a queue or car park. Relief!
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