If you know how to locate the horn behind the radiator, un plug the leads at the horn and put a meter to them while pressing the horn button. (Bike or key on). If you get power, your horn is bad. If there is no power you will need to trace to wires back and check all connections. Don't know if there have been any horn button problems. If your horn is bad, many of us have our old ones we would be willing to give you. Some horns can be re activated by spraying WD40 down the throat. This generally requires horn removal though and I am not sure if it works with the V horn.
Ha, GW beat me to it while I was typing!
'07 HD SEUC