How to install wolo air horn #519 2004 ultra - 2004 Harley Davidson FLHTCUI Electra Glide Ultra Classic

If you are trying to make it work simultaneously with stock horns, I suggest you wire it in through a relay. Without a relay you will be placing too much of a load on the horn circuit.
A relay is typically used to control a component that draws high amperage. The relay allows full power to the component without needing a switch that can carry the amps. The switch only controls the relay. The relay then provides a direct connection to the battery. It should be noted that either the power(86) or ground(85) in the relay control circuit can be switched. In the case of a horn, the horn button would be used to switch the ground lead(85) and power(86) would be provided directly from the fuse box.
This is a typical wiring diagram for a standard relay installed for headlights, horn, fuel pump, electric fan, etc. If the relay has a 5th terminal, it is not used.

Check power to the unit and power coming out of it. The pumps go bad on the horn like that a lot.If you have access to an air compressor then run air through the line to the horn portion and see if it works. If it does then more than likely it's the compressor unit being bad.

I’m happy to assist further over the phone at https://www.6ya.com/expert/robert_5bac37c3cb991fdb

send it back

There's two of them located just above the parking light in front of each of the fender wells. You will be able to see them from the bottom looking up

use a standard horn

It is possible that you may have reversed the polarity on the compressor; it may be "pulling" air instead of blowing it out. Remove the air hose from the compressor and put your thumb over the air outlet while pressing on the horn switch. If you don't feel air blowing out, reverse the positive & negative wires going into the compressor and repeat the test. The air horns should work at this time.

Note: Always install a relay on this type of horn system; the compressor puts a high amount of load on the horn switch if you don't.

Try writing Wolo an e-mail and request a wiring schematic.

http://www.wolo-mfg.com/motorcycle.htm

Good Luck
Steve