Originally Posted by Chip O
And a stuck relay has been ruled out?
And like Mr cruiser stated, the wire in the column could have worn bare with the turning of the wheel, and is grounding out permanently.

The ground path travels up the center steering rod to the wheel. Pressing the horn button connects down the column wire to under the dash and to the relay. A short to ground completes the circuit, but a short on any of the positive side of the circuit to ground will blow fuses. Unplugging the column wire under the dash and fixing it will say it’s not the relay.

I installed a horn button on the colum, and the horn works great. I believe the wire in the column most likely has bare spots and is grounding, causing the horn to blow continoulsy. I will eventually replace the mast bearing / wire but for now, my horn works great again.

1953 3100 with 1957 235, T5 and 12 bolt 373 rear