If this is OEM wiring, I'd leave it alone!
I'm sure it's not doubling up on the volts!
I found a HORN diagram in "Prodemand" for a GMC K1500
(If that's wrong, lemme know, I'll look again)
I'm not seeing anything that could 'draw' (My Deductions) without the Horn blowing!
The relay is the only thing that could be an issue (I'm not an auto electrician) Computerized vehicles are not my cup of tea! I like to deal with carburetor vehicles!
I do research things pretty well though!
Seems the computers have taken over every vehicle component in some way.
Alarm system work with the horn?
I am more than happy to look for SPECIFIC diagrams for your vehicle (the whole nine yards would take me weeks!). Should you need more, please verify your vehicle info, type fuel, sub-model, anything that will aid me. Prodemand prompts all info from me to get to the right diagrams.
Click on the diagram below, it is the K1500 diagram
Wednesday, November 30th, 2016 AT 7:33 PM