I rewired my truck with the EZ wire harness and everything was working fine. Went out the other morning and the horn wouldn't work. Checked fuse, its good... Pulled horn button from column and got a nice little tingle when I touched the wire that seats in the column. Got the horn to work a couple of times with key off but nothing with it on. Now I have nothing....

Ground is on the frame and it appears to be good.

 

Not sure where the relay is mounted, is it part of the circuit board? Do you have a good ground from cab to frame?

 

Should be easy enough to test. Power to the relay should be the center post and that comes straight off the hot side of your regulator (BAT). One side post goes to the horn. The other side comes from your horn button, which should be ground.

If you short the center post to the wire going to the horn, the horn should sound. Be careful not to hit your head!

And don't leave it like that for very long, just a brief test.

If the horn sounds, obviously, the horn is good. If it does not sound, the relay may be bad, or you may not have continuity to ground through your horn button. To test the relay, short the horn button terminal to ground. Don't bump your head! (ask me why I keep saying that) .

I think your horn circuit should look like this.

 

Relay is attached to the firewall under hood. Joe your diagram is close, I'll follow your tests tomorrow.

Thanks

 

Easiest and first thing is run a wire direct from the battery or other known power source directly to the horn and bypass all the circuitry to test the horn. As mentioned, don't knock yourself out when the horn blows.

 

Got it, check horn by bypassing relay, check relay by shorting out horn button at relay. Ok what happens if horn and relay are good?

 

Check horn button, wiring and grounds

 

The relay operates with power to it constantly, and a ground applied by the horn button. That ground completes the circuit, the relay closes, and power is supplied to the horn(s). If the horn(s) are not grounded, they won't make a peep. I found this out the hard way after I removed mine to refurbish them. Mine are mounted to the inside of the hood. I loosened the mounting screws, which disturbed (think rust) the ground to the horn body. No honk. So, if the horns don't honk when the relay is bypassed, check that the horns are grounded to wherever they're attached. But you still have to supply the ground to the circuit.

If horn and relay are good, it's simple. The horn button is not supplying the ground. Wiring is open most likely.