If the horn only "has one wire coming from it" it is depending on the frame of the horn being grounded and the "one wire" having 12v when you press the horn button.
1964 C-10 wiring diagram shows a horn wired that way and the use of a relay. I don't know about a 60 model, but late 50s also used a relay. Buy a generic horn relay at FLAPS and wire it like this:
Last edited by Bill Hanlon; 12/14/20235:28 PM.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
