I want to hook up an air horn, but I think you need to use a relay??? But I do not know how these things work. Can anyone please explain to me the basic idea in seting up a relay with air horns.

Thanks,
MAXecutive

 

check out http://www.hornblasters.com/diagram.jpg

you shouldn't need a relay, just wire a switch to your solenoid.

 

I'm not sure how much current the air horn compressor is gonna draw, so you might not need a relay, but if you are doing it with the relay, the idea is that the relay itself is gonna act as an electronic switch, which you are gonna trigger when you hit the horn on your steering wheel, so you could use the cable that connects to the stock horn to trigger it by connecting it to the 86 contact on the relay, then ground the 85 contact, connect the 30 to the positive on the compressor for the horns, and the 87 to a fused cable going to your battery or other 12 volt cable you could find closer.

 

This is answered in the FAQs...