Is this new harness made for your truck or is it a universal replacement?

From your post it sounds like it has a fuse box with the relay mounted there. The manufacturor should be able to tell you which wire goes to your button wire.

On 2 wire horns, one is a ground.


"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.