First thing is to pull out the horn relay.
Then trace the wiring by downloading the relevant year KJ Service Manual here...includes the circuit diagrams.
Could be the clock spring under the steering boss is faulty....some KJs have "hood open" switch on the right hand side inside the engine bay. If this switch goes faulty the BCM thinks someone is trying to hot-wire your Jeep and blows the horn....you need to try dis-connect this switch or short it out...not sure which one overides the function of this switch.
Manuals here:
http://www.colorado4wheel.com/manuals/Jeep/KJ