Hallelujah my horn works!
im posting this because after reading countless posts I had to go through every piece of my horn system. I was about to tear apart my airbag to see if the button was fixable. ( ya I know.)
Having a good diagnostic light was my saving grace. One that has power in it and can switch the tip to ground or power.
anyway I determined my steering column was not grounded.
the mounts that hold it under the dash are grounded so I had connected there but when I put the wire from under the airbag to the steering wheel frame it didn’t blow the horn. It did when I connected my test light up it and put the tip to ground. I ran a temporary wire from a mounting bolt to the steering column frame and viola it works.

not pretty but the next time I’m out I’ll grab a stainless braided ground wire and put a bolt through that hole. Put the other end on the threaded stud with a second nut and it should be good permanently. (?)

Before this I had unbolted and remounted both horns, replaced the relay,replaced the clock spring (2x).wired in a temporary switch on the dash.
Black wire with red tracer on the white connector going into the clock switch is the horn on my 99 Cherokee. Ground that and the horn blows.
hope this helps some of the others out there in Jeep land with similiar horn issues.
Now for my my next issue to get the windshield sprayers working. ( need to replace the pump). Maybe next weekend. lol.

 

Great find on that steering column ground. A dedicated ground wire from the column to the dash frame is the perfect fix. That missing ground is a classic, sneaky horn problem. Good luck with the washer pump next weekend.