Get someone to hold the horn button down and measure both terminals on the horn to ground. One SHOULD show battery voltage and the other SHOULD show zero volts when the horn button is pressed. This is not how I understand your statement above "Pushing horn button applies 6v across the 2 wires".
'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.
| 
