I have been wracking my brain trying to fix this problem for months. Every once in a while I wake up to find the horn going off continuously, mostly in the middle of the night (of course).
After a couple of trips to the mechanic I finally figured it out:
- it only seemed to happen when my jeep was parked head in on my driveway, which would mean the jeep sloped downhill.
-it also only happened after a heavy rain.
I FINALLY took the thing open after this happened to find a small drip of water coming down BEHIND the fuse box. What I finally figured out was that the sunroof drain on the driver's side was partially clogged, meaning that during a normal rain it would be okay if it was parked nose uphill or if the rain was light, but when it came down in buckets, the drain would overflow and then drip down along the frame channel into the fuse box and short out the horn.
So, next time you have an uncontrolled horn incident, check out the sunroof drains!