I have recently acquired a 91 Ultra Glide. An absolute beauty! However, the horn makes a "thonk" sound when activated. I replaced it with a little over the counter car horn, to pass inspection, and it does honk, but real whiny. I purchased a new OEM horn from the dealer. Same result. I got 12 volts, at the wires, but no honk?? When I attache the new horn to my battery charger it works fine. I'm thinking it may be an amp issue, but i dont have an amp meter. Any direction or thoughts would be fantastic!!