Horn, wiring, and installing an air horn

[JohnT]

So I tried to install a Screaming Banshee horn yesterday and failed entirely. I may have actually destroyed the horn in the process. This is the second SB horn I have installed but it is the first of the new generation of SB horn that I have installed. The instructions are simple and straight forward.
From what I gathered yesterday the right side horn has both wires "hot" and the shifter side has 1 hot and 1 ground. What the heck?
I wanted and paid dearly for the momentary tap producing a mellower tone and a .15 second or longer press producing a deafening blast and light pulsation.
So, finally on to my question. Has anyone wired an air horn to the stock horn button? And how did you go about it?

[Tonyvdb]

You cant wire a horn like that directly to the horn button as it draws far to much power and can damage the horn button. You need to hook the horn up to a relay that goes directly to the battery and have the switch curcuit only power the relay its self.



Diagram shows both an air horn and two normal horns, I would not even bother hooking up the normal horns again.

[Mr Jensee]

Also it pays to get a simple volt ohm meter. Harbor Freight has them for less than $10 or Lowes and Home Depot also carry them. it will save you a fortune in diagnosing electrical issues.

[JohnT]

You cant wire a horn like that directly to the horn button as it draws far to much power and can damage the horn button. You need to hook the horn up to a relay that goes directly to the battery and have the switch curcuit only power the relay its self.



Diagram shows both an air horn and two normal horns, I would not even bother hooking up the normal horns again.

This horn has not only the relay built in but the relay itself acts as a low volume (short tap of the button) or full volume with a held horn button
The horn is wired directly to the Pos and Neg of the battery. There are an additional 2 wires to be wired to the horn circuit. And a 5th wire to go to the high beam circuit to also flash the headlight. These blue and 1 yellow wires come from / go to the horns built in relay. The horn can also be set using the PC type jumpers to either be full on / no headlight flash or low and high volume / with headlight modulation.
The first Screaming Banshee I bought a few years ago worked great on my old Venture Royale and it still does.
I will be the first to say I'm not an electrician. (my Dad was) I have basic theory and years of trial end error to my favor. My first thought on this problem is that power passes through the the right side horn and goes to the left side on one post only. The ground of that horn I am betting is to the frame. But as I said, I'm not an electrician. I seldom need to ask advice on the simple stuff like this. But, as we all know, if you are stumped, ask.

[JohnT]

Also it pays to get a simple volt ohm meter. Harbor Freight has them for less than $10 or Lowes and Home Depot also carry them. it will save you a fortune in diagnosing electrical issues.

Have one, used it. That's how I determined the (I thought) odd wiring of the stock horns. Both wires to the brake side horn were hot and the shifter side horn is hot and ground as would be expected. The horns work perfectly but if you unhook the shifter side horn you get just a sick cow moan fron the brake side horn. Which is what I expect when a horn has no ground or a bad ground.

[randallar]

Ok I looked at your wiring and I looked at the horn schematic, it looks like the horn is pos to both horns and the horn button is the ground. If that's the case you should be able to pick either horn and tap into one or the other but not both. I don't why its not removing the horns but that's the way it is. Find the pos going to the horn which should be a brown wire and the black w/yellow stripe goes back to the horn button for ground. If anybody else wants to chime in it would be welcome.

[krasmu]

I'm not he best electrician but I'll throw this out to you. Are you sure the brake side horn is really working properly? Maybe it is shorted out and creating a positive through the unit. I'm not even sure if that is possible. Just think someone needs to ask the obvious. Double check that the horn is actually working correctly before looking deeper.