The Stovebolt Site Forums The Shop Area The Electrical Bay proper way to wire a horn

I picked up an ahooga horn from the auto parts store and I'm curious as to the proper way to wire it in. The original horn does not apear to have a fuse or a relay. The new horn recommends a 30 amp fuse.

My question is do I need a fuse and should I place a 30 amp (or whatever is suggested) relay somewhere in the mix? In general, how would you wire a horn in?

Thanks Rick...........

Rick,

There is usually more than one way to skin the proverbial feline. If you aren't worried about stock appearance, this is how I would do it.

Use a horn relay mounted near the horn. Power the relay from the starter switch or some big fat connection off the battery. Use a nice gauge wire...maybe a #10 or #12, and stick a inline fuse in it if you want.

Wire the ground for the relay up through the steering column as it is normally done. This is a relatively small gauge wire...maybe a #14 or even a #16.

Mount the horn somewhere secure and you're all set. Some horns ground through their frame, some have a post that must be wired to ground...I don't know which style you have.

Stuart

Rick are you saying the ground on the relay when gounded makes the horn blow i havent hooked one up in my truck but getting ready to soon

32fire2,

I'll assume you directed the question at me. Yes, one of the three terminals on the relay actually grounds the small internal coil which causes the points to close and pass power from the source to the horn.

This low current ground is made when you push the horn button.

Stuart

Stuart,
Thanks for the tip, Ill find a place to hide the relay. The stock horn button is a litle stiff in the sterring wheel. I think I'll take a small wire brush and knock the crud off.

Rick..........

When connecting the relay it is worth noting the 12v supply to the horn relay via a inline fuse must also loop to one coil connection on the relay , ground wire connected to the other coil connection on relay then passes to the horn button via the column or aftermarket pushbutton. There other ways but this is the simplest form.
If the circuit is fused at 30amps keep all wiring the same size as the fuse will allow fault current upto the fuse size to pass thru the system, insulation on any smaller size cable could melt if there is a fault in the system. Insulation melting causes smoke. You do not need smoke signals

Terminal 86 12volts from supply source loop to terminal 30
Terminal 85 ground via horn button or push button
Terminal 30 12 volts from supply source
Terminal 87 12 volts to horn

usa050aus,

That's a very good point. The 'Bosch' type relay does have two external connections for the pull-in coil so it would be wired as you indicated. A typical automotive horn relay will only have three terminals, as the pull-in coil receives power via a internal jumper instead of a external connection like the Bosch style.

Stuart

OK stupid question time if I may. I was given a ahooga horn and the diagram also shows a relay. Can I just wire it to the pos on the batery with a fuse between and then to a togle switch and just ground the horn?? I'd just be giving a flick of the switch.

Tedy,

That's a perfectly fine way to do it. Just make sure the wire size and switch are rated for whatever amount of oink the horn directions call out. I would use a push button instead of a toggle switch, but to each his own. The fuse is important, don't shine it on.

Stuart

Thanx Stuart thats what I thought and yes you are rite I'll go spend $5 on a push button