The horn is located under the battery. You access it from pulling down the front bottom part of the fenderwell from underneath. Your horn is actually 2 horns. They are notorious for grounding themselves out. Yours may only have one of the horns out.
When you feel in there, you will feel the power wire to one, and a jumper running to the second. My guess is the jumper has either broke or come off. If the horn grounds itself out, you will lose both the horn and your cruise. They are run through the same circuit in the main Distribution Block under the hood next to the back of the passenger side fenderwell.