Never heard of using a ballast resister on a horn. Most people just blast them with 12V. If you use it, it would go between the relay and horn.

The wire coming from your steering column should be a ground. With a meter make sure it is grounding when the button is depressed.

The horn relay has 3 terminals. Make sure you have 12V going to the power terminal of the relay. Ground the ground terminal to the cab with a screwdriver and you should have 12V to the horn terminal.

Next apply 12V to the horn. It should honk.

If all these are OK then wire it up and it should work. If any of the steps don't work, that is where your problem is.

"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.