BruceB

Yes, old thread, but not a old problem for new poster.
First, you will need to check that you have current to the horns.
Pain in the you know what to get to, but use a multimeter or volt indicator light on the wire to the actual horn and have someone push the horn button.
If you have current to both horns, then it is possible the horns are bad, but unlikely that both would go at the same time. Since the mounting bracket is the ground for the horn I would take them off and clean the area where they bolt to the Jeep.
If you still don't have horns, then try a replacement horn to see if that works.

If you don't have power to the horns, you have a wire grounding out before the current gets to the horns.
Unfortunately, that will be tracing wires from the horn button to the horns to find it.
Could be a wire chafed and grounding out somewhere.

Of course, check your fuses and relays first if you have no power at the horns.

Idunno

Update on a 98 Classic I got with the horn inoperative:

1. The airbag switch is shorted closed. It's a laminated switch consisting of two copper plates and a wire terminal on each plate. As manufactured, separating the two plates was an air gap (bubble) that was sealed in by an adhesive binder all around the edge of the laminated plates, like an air pillow. Pushing on the horn symbol on the airbag cover pushed one plate against the other. Removing pressure allowed the air to expand them apart again. Either the PO burst the bubble with an angry fist to the horn, or time opened up the seal and the air escaped. In any case, the switch is shorted. I can repair it by placing some plastic card between the plates, with a hole centered on the plastic card, and re-bonding the edges together. Experimenting with it, it works. So, the switch is repairable.

2. Both horns are dead. No ohms, no sound when tested out of circuit.

3. Horn relay works fine (also tested out of circuit) and I have battery voltage across the horn fuse (#21 - 15 Amp). When I got the Jeep there was a much heavier fuse in that location and it was open. Wild guess, the PO wasn't a whiz kid.

4. No power to either horn from fuse 21. Somewhere along the circuit the DG/R wire is open. I'm not going dumpster diving to find it. I'm making a wild guess that the PO's attempts to get his horn working with a larger fuse took out the wire somewhere along its length.

My solution is to repair the horn switch as noted above and then run a separate wire from the fuse block at fuse 21 out to the new horns. To do the latter I'll run a separate wire from the relay (Contact 87) to the horns. My kid is taking the Jeep up the coast to Bangor and back in a couple days so I'll work the problem on his return.