Air Horn Hook up

I want to hook up an air horn instead of my stock horn. i was wondering if anyone knows where the horn is located on a 99+ GMC Seirra, or a silverado, (same vehicle) and/or also if anyone has done this, what is the easiest way of going about it. I.E. where to disconnect the stock horn and whatnot. Thanx

have someone honk it and listen where its coming from, use a dmm to see if the wire is sending a neg or pos signal to turn on the horn (most likely pos)shold have only 2 wires going to the horn

most likly in the grill or one of the fender wells. look up from the ground under the vechile. a relay to bring power to the air pump would be what you need to do directly ground air pump  to chassis and i believe it is a switch ground to the horn and a constant pos. so you'll need to use the ground but always double check all wires usind dvm or test light.JUST ONE MORE AMP!!!

hu,alpine cva 1005/dva 5205

sound processor,symmetry(first one).

sub amp,power 1000 the terminator.(1992).

subs,spl comp dual 1 ohms.

punch 150hd on a 10" ev.

alotofhighs