I’m assuming your wires are accessible at the relay? If so, you’ll need to test for basically four likely scenarios:

1. The fuse in your auxiliary power wire has blown
2. The horn itself has failed
3. The switch on the handlebars has failed
4. The relay has failed

#1 – I’d start here. Assuming you installed an inline fuse on the wire you ran from the (+) battery terminal, make sure that hasn’t blown out. If it has, the relay is asking for power via the handlebar switch (the noise you’re hearing) but not getting any current from the battery.

#2 — The easiest way to check if the horn works is to hook it up directly to a 12V battery source like a car battery. Depending on how you’ve installed it, you’ll have to figure out the best way to do that. Pro tip: wear ear plugs!

#3 — If you are hearing a click or other noise when you press the switch on your handlebars, then we can likely rule out the handlebar switch. The way to test for sure would be to unhook the wires from terminal 85 and the one opposite on the relay (the OEM wires). Hook up your voltmeter to those two wires and push the horn button on your handlebars. You should get current. If not, then either the switch is bad, or something has unhooked or shorted between that switch and the relay in the OEM wiring. But again, if you’re getting a click or a buzz at the relay, then that switch is probably fine.

#4 — If the relay is bad, the way to test it would be to unhook the horn wires from the relay (the two wires at 90º to terminal 85), hook up the voltmeter to the relay on those terminals, then press the switch at the handlebars. If no current passes through the relay when the switch is pressed, then there you go: dead relay. Replacement relays can be had easily at your local auto parts store in the driving lights section. It even has terminal 85 labeled, so the replacement should be a direct one. The one relay one I had to replace even had the mounting tab in the same spot.

Hope that helps.

how do you test:
double check continuity on your wires
make sure you’re grounded to the frame

i can hear my relay doing something when i hit the horn button, but no honk.

The scooter I use as the example in this article is 12V neg earth, so the wiring diagram should work for you just fine. If you’re replacing your existing horn, then just follow the instructions verbatim. If you’re supplementing, then you’ll need to splice into the positive wire for your existing horn to the relay instead of simply plugging it in. Does that make sense? You’re using the existing horn wire to trigger the relay and the new wire you’ve run from the battery through the relay to power the new horn. Good luck!