Horn works like this. Power goes thru fuse or fusible link to horn, then to wheel horn button switch, then to ground. If you don't have power to horn, trace that wire back to fuse or fusible link. If you have power to one horn wire and not the other, the horn has an internal circuit break. If you have power on both horn wires, and none at the horn switch, you have a broken wire between the horn and switch. I assume you've checked the horn fuse?

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