Check for power (12V+) at the dark green wire at the horns while depressing the horn button. If you have power there, make sure the horns are grounded. If they don't work, they have become defective. If you have no power there, and the relay is clicking, check for power at the terminal of the relay that the dark green wire is attached. If you have no power at that terminal, the relay is bad. If you have power there, the wiring between the relay and horns is bad.
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