Strange horn problem

mitsubishi
galant

#1

While driving to my parents for the holidays, without warning or provocation, my car’s horn started blarring. At first, I thought it was simply stuck on. However, when I reach the next exit ramp and began to slow down, the horn began to beep more slowly in direct relationship with the decreasing speed. After having a look under the hood, I was able to rule out the upper horn as the problem – the car continued to beep (faster as the speed increased) even after I unhooked that horn. To temporarily resolve the problem, I had to pull the 15 amp fuse for the horn system. Any idea what could be causing the problem? My wife and father seem to think there must be a short with the speedometer, but I am very skeptical of this idea. Many thanks!


#2

You are right to be skeptical about “short with the speedometer”. To me, that sounds like a wild guess with limited technical background.

Speaking of wild guesses with limited technical background, here’s mine: If you have an alarm system that is supposed to beep the horn if the car is being stolen, maybe something there is on the fritz.

Anyhow, if the upper horn still works OK, you can disconnect the lower horn and drive the car until you can trace out the source of what’s beeping the lower horn. I’d try to get a wiring diagram and do just that. I’ll bet the answer will be real interesting.


#3

I don’t have service data for your vehicle but I suspect the horn circuit has a switched ground connection to activate the horn. There may be broken spot in the wiring insulation that is touching ground and turning on the horn. Check the wiring near the horn that is having the trouble and look for any signs of wire damage. The trouble could also be in the steering column but since you say that only one horn is having trouble I doubt that is the case.