I have done this a number of times, though on other vehicles. I agree with starting at the horn itself. You might can trace the wire back to an more convenient spot under the hood. My additional suggestion is to tee into that wire and keep your factory horns functional, and use the tapped-in wire as a signal wire to your new air horn relay. I've found that sometimes with the add-on air horn system you can blow a fuse, lose a relay, have an air leak, have a faulty air solenoid, compressor, pressure switch, etc., etc. It's best that you not find that out the hard way when you really need a horn and have absolutely none.Planning an air horn install on my new truck (don't have it yet) I will need to tap into the stock horn wire to run a relay to fire the air horns. I was wondering where an easy place to get to it is?