Horn blasts on its own?

[Bob]

Had a couple of frosts and a little snow a while back and couple nights ago it got pretty darned cold. An old problem from the end of last year reared its head again. When the temperature drops below maybe 20-ish my horn goes off. The other night while at the local Legion a buddy came back in and told me my truck was freaking out. Fortunately it was one of the rare instances when my dog wasn't in the truck waiting on me.

Question... Anybody ever experience this and any clue what's going on? I'm figuring it's got to be a contraction thing. Something is shrinking in the cold and setting it off. I fooled with it some Saturday and thought maybe I got somewhere with it but it was fairly warm out . After the sun went down I heard it out there howling again so I just unhooked it. Unhooked it at the steering wheel so I wouldn't risk running my battery down or maybe screwing up my relay? I couldn't figure how that goofy plastic covered flat strip in there works? (72 with the two bar style wheel) It doesn't seem to be a case of the middle of the wheel pad hitting the shaft? The spring loaded button under the steering wheel has to be good since it's sending juice to make it blow. Ground is good since it blows. What is the switching mechanism? Is it in that flat strip? Maybe a wire in the rib on top of it getting pushed to the flat metal strip? Or now that I think of it maybe something to do with the channel shaped metal thingy under it that's sort of attached by the rubber cover?

Any info would be appreciated...
Thanks,
Bob

[Montana71-F100]

I had the same problem with my '71. I don't know how a '72 works but my problem was in the steering wheel. There is 2 long flat pieces of copper that were too close and when it got cooler, well you know what happens. It's been a couple of years but it seems to me that there was a plastic frame that had some breaks in it. I used JB Weld or Water putty made by the same company that allowed me to repair the plastic so the pieces of copper weren't so close together.

Good luck!

[Bob]

71 & 72 are same I think. Maybe later years too? Thing that chaps my butt is I bought it new not too terrible long ago and it looks fine? Case of aftermarket crap maybe.

[basketcase0302]

I'd almost bet money on it being bad. You could troubleshoot by pulling it out / stuff it in the freezer / run a continuity test when it's chilled down.

[Bob]

It was something to do with the horn bar. Got a new/ used one from a fellow on this board from Colorado and it's working fine and dandy...!!