Many moons ago, I had a ski house in Vermont and every holiday and weekend, about 10 of us would pack together in an Animal House atmosphere of skiing and overindulgence.
One notoriously cold Vermont winter night, the temps were hovering around -35F, and a car horn in the driveway started blaring about 3AM for no apparent reason. This was 3AM on Saturday after a full day of skiing and a full night partying. Obviously, no one wanted to go out in -35 temps to deal with it.
My buddy "Sparky" went from room to room waking people up telling them to go shut up their horn unsuccessfully. Finally, he came in and woke me up and said "Your horn's blarin' out there...go shut it up". I listened for a moment and said "that ain't my horn bud. My horn is manly sounding and that thing sounds like a foreign car horn to me. (Sparky owned a Mazda) He insisted that it was my horn and then got everyone else all riled up and demanded that I go out and deal with it because I was the one who understood car stuff. Well, I put on all my clothes for -35 and off I trudged out into the Vermont chill to the driveway only to stop dead in front of Sparky's Mazda who's horn was blaring wildly.
Long story short, I was more than a little [censored] and figured that condensation in the horn relay had frozen up closing the relay contacts, or that the extreme cold had shrunk the metals and closed the relay. I quietly went back in the house and told Sparky I had to move his car to get mine out and got the keys to Sparky's car. I then drove his car down the road and parked it facing away from the house and hiked back leaving it to wail away into the night air. By morning the battery was dead, the car was 1/4 mile away on a desolate Vermont road, and as we all left to go skiing Sparky was still waiting for someone...anyone...to give him a jumpstart with THEIR jumper cables (you don't think he had any do you?). After waking up the whole house first with the horn and then secondly to try to blame everyone's car but his own for the problem, no one would help him jump the little Mazda with a now VERY dead battery. You can't imagine how busy the tow truck guys are when the temps are -35 in ski country.
Sparky finally got a jump and the instant that he got the juice in the car the horn started back up and it was fused closed now as best as I can determine. I told him to cut the battery cables but he wasn't that stupid...after all his name was Sparky for a reason. He was halfway back to Massachusetts before the horn finally quit.
A replacement relay fixed the problem.
The moral of the story is that horn relays can do some crazy things, even when you think it makes no sense at all.
