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Horn stuck in On position

Recently my car horn became stuck in the on position even though I was not driving the car or using the horn. In fact, it got stuck in the middle of the night!! To stop the horn, I simply removed the fuse for the horn, but I was curious what sort of issue would cause this problem and what should be done to fix it.

Well, the problem might be with the horn switch on the steering wheel, but I’m guessing it’s more likely a stuck horn relay. If your horn relay is identical to other relays (as it is in some cars) you can swap to test this idea.

The horn switch is layered into the padding that covers the air bag. The plastic can curl and close the horn switch when cold.

I had the same problem years ago with a 1971 Ford Maverick and my brother had the same problem with a 1977 Cadillac. In both cases it was the horn switch that was layered into the padding. However, neither the Maverick nor the 1977 Cadillac had an airbag. The Maverick didn’t have a horn relay–the full current to the horn went through the switch.

If your problem does turn out to be the switch, you can do a cheap repair by buying a horn button that mounts on the side of the sterring column and bypassing the switch in the steering wheel. I think auto parts stores probably still have these auxilliary horn buttons.

One problem with removing the fuse for the horn is that this same fuse may also be on the same circuit for another electrical component. Hence, while silencing the horn, you may be eliminating another accessory/feature. This may involve something trivial, or it could involve some function that is important.

Let me give you an example. On my '71 Dodge Charger, I had a situation on a couple of occasions where I had left the driver’s door open for an extended period of time while the engine was idling. (I was off-loading some large items that I had bought.) The extended buzzing of the door-open warning caused the relay (which controlled both the door-open warning buzzer and the horn) to overheat, and I wound up with a jammed-on horn. Obviously, the short-term solution was to disconnect the horns until the relay cooled down and functioned normally.

After this situation occurred for the second time, I realized that this was an inherent design flaw. What did I do? I consulted my Dodge Service Manual regarding the circuitry of the relay for the door-open warning and the horn, and I sawed off the contacts for the door-open warning. This preserved the functioning of the horn, while eliminating the door-open warning buzzer.

Yes, I never again had to hear the dulcet tones of a buzzer telling me the obvious–that my door was open–but the best part was that I could leave the driver’s door open as long as I wanted while the motor was running, and never again had my horn jammed in the “on” position.

Check to see what else–besides the horn–is linked to the fuse for the horn!

Above comments are excellent. I’ll add that if this were my problem, the first thing I’d do to start the solving process is look at the wiring schematic for the car. It’s difficult to know where to start without the schematic.

Don’t have a schematic? The best bet (as suggested by VDC) is the shop manual. Those can be hard to find for older cars. But usually you can find schematics in Chilton’s manuals too, which are readily available. Your public library likely has one for your car. You library may also suscribe to the All-Data database service. It’s a sort of computer-manual. You can check that for speciific horn related known issues with your make and model and year, and it likely has a horn schematic as part of that database.

Also, try Googling your make and model and the phrase “Horn schematic” . It might just pop up right there on your computer screen.