The horn wire inside the column could be worn and shorting against the steering column. It's included with the turn signal wiring. You may need to remove the TS wire loom to find the issue.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine