When the temp drops below freezing, our car's horn starts beeping.

Dear Car Talk

Dear Car Talk | Feb 01, 1999

Dear Tom and Ray:

We have a 1989 Dodge Shadow. In the middle of a frigid winter's night, we
thought we heard a car alarm going off at about 2 a.m. It turned out to be our
car horn. It seems that any time the temperature drops below 32 degrees, ice
forms behind the steering wheel and sets off the horn. When we brought it to the
"car place," they said we have to bring the car in when it happens. Since it
happens in the middle of the night, that's not realistic. Now what we've been
doing is disconnecting the horn on any night when we think the temperature is
going to drop below freezing and then reconnecting it in the morning. It's
getting tedious. At this point, even our 10-year-old son knows how to disconnect
the horn. Can you help? -- Fran

RAY: I don't think it has anything to do with ice itself behind the steering
wheel, Fran. It's much more likely to be either the horn contacts in the wheel
or the horn relay.

TOM: There are metal contacts in the steering wheel, and when you push on the
horn button, those contacts touch. That trips the horn relay, which makes the
horn blow. If the contacts are out of adjustment, cold weather could cause the
contacts to shrink and touch, tripping the relay and sounding the horn.

RAY: The other possibility is that the cold weather is causing the horn relay
itself to close, skipping the steering wheel contacts all together.

TOM: So here's what you do. Buy your 10-year-old son a "puller." And on the next
really cold night, have him use it to remove the steering wheel. Then take the
wheel to bed with you. That'll take the horn contacts out of the circuit. Then,
if the horn blows in the middle of the night, you know the problem is the horn

RAY: If you don't feel like sleeping with your steering wheel, you can ask your
mechanic to just go ahead and replace the relay (it costs about 10 bucks) and
see if that fixes it. If it doesn't, then you know it's the contacts in the
steering wheel and you can ask him to fix or replace those next. Good luck,

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