A horn that will not blow.

Dear Car Talk

Dear Car Talk | Jul 01, 1990

Dear Tom and Ray:

I found a recent column of yours to be not only very interesting but also amusing. It concerned a car owner with a horn that would start blowing in the middle of the night in very cold weather. I have the opposite problem. The horn on my 1989 Skylark won't work until the car is warmed up; after about 15 to 20 minutes of driving. I've had it into a repair shop three times without success. Any ideas?

TOM: Gee Harold, you raise an interesting philosophical issue. Is it better to have your horn activated or inactivated by cold weather? It's a tough call. That other guy wakes up half the neighborhood and has to go out and disconnect his battery in his bathrobe. But you have to roll down your window and yell "LOOKOUT!" for the first 15 to 20 minutes every morning.

RAY: Anyway, if you remember, Harold, the guy whose horn blew in the middle of the night had a problem with "shrinking contacts." Cold weather causes things to shrink, and the horn contacts in his steering wheel were shrinking until they touched and blew the horn. It's possible that your contacts are shrinking the opposite way in the cold--that is shrinking APART rather than together. But that's only one possibility.

TOM: There are other parts of the horn system that could be affected by the cold weather. Do a little detective work. Next time your horn doesn't work, open the hood and listen carefully. If you can hear a faint gulping sound, the problem is prob?ably the horn itself--or, if you're lucky, the connection to the horn.

RAY: If you don't hear any groaning, see if you can hear a "clicking" sound from underneath the dashboard. The clicking is the sound of the horn relay. If you hear it, that means the relay works, and, again, the problem is probably the horn. If you don't hear the clicking, the re?lay could be faulty. Replacing the relay is cheap and easy (although finding it is hard, especially if it's not clicking!).

TOM: If there's still no clicking after you've replaced the horn relay, then the problem is in the steering column. In that case, your mechanic will have to remove the wheel and fix it for you.

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