Have a 1999 Grand Cherokee Limited 4.6 V-8 engine 200,000 miles.

My current problem is horn keeps blowing when parked unattended at will for unknown reason.

This past Saturday early morning had to disconnect battery terminals, when horn blasted me out of bed. After removing battery cable, decided to clean terminals with wire brush when reinstalled, horn did not blow, great! Problem fixed itself wahoo!

Next day used wife's car as we needed to run errands, when returning home late Sunday night, my neighbor met me at my door stating my jeep's horn was blowing for ten minutes, he was kind enough to disconnect my battery saving my jeep from being destroyed by irate neighbors holding pitchforks & brooms.... scary!

Anyone ever had this happen to them? What can I do for a quick repair?

Appreciate it,
Pe Pop

 

Don't have a WJ, but I think this is your horn circuit diagram.

Is it a constant/sporadic tone, or a regular on and off honking?

If the latter, I'd look into the alarm system.

If the former, Just saw your other post. Since it is a constant tone, I'd troubleshoot the components on the diagram below. Relays are easy to test, so I'd start there. If not that, maybe check the horn switch and clockspring.

That's not to ruse out the alarm system completely, but it seems less likely.

 

Has it been extremely cold lately? The plastic shrinks around the horn switch under the airbag and sets it off. You could just pull the fuse for now. OR the relay so you'll still have your power outlet.

 

Thanks for the useful insight & wire diagram!

Pe Pop

 

Another sound solution, thanks!

Pe Pop

 

I see what you did there!

 

LOL, You don't need to be teaching high school auto mechanics, you need to be teaching at MIT or oxford.

 

Actually, this goes back to a problem I encountered with my boss's new Oldsmobile in the 70s. It had a squeeze-ring for the horn. The horn went off in the hot sun because the plastic swelled. I told him to just leave the windows cracked open an inch or so, and that cured the problem.

I worked in plastic molding most of my adult life. You can change the finished product's size by controlling the molding process; ie cooling time and injection pressure.