With a jumper wire ground the horn case to the batt neg post then jump 12V from the batt positive post to the horn terminal to see if the horn itself is good. If the sound is weak see if the horn has a "sound trimmer" knob & turn it SLIGHTLY to the right then to the left then back to center & repeat jumping it. If good hook the horn back up & go to the horn relay and ground the wire/terminal that goes to the steering column & see if it honks. See if you have voltage to the relay and continuity from the wire from the relay to the horn. Electronic voltage regs are either good or bad so the reg ain't the problem but make sure it's grounded well. Poor connections anywhere or alt (brushes which are easy to check or poor connection/continuity somewhere inside the alt) or way less likely a bad batt. Not sure where to advise you to start on #3 but www.mymopar.com has wiring diagrams for you but I would unhook the drain on the battery & charge it up and remove the jumper on the fuse box till you get it