[boyt911sc]

Tom,

The horn wiring circuits for '75, '76', 77, and SC's ('78-'83) are the same. They have not changed a bit. The power to the horn relay comes directly from the battery and uses no fuse. It is connected before S18 and goes to the horn relay (J4).

Horn relay tests:
Check if you have power @ terminals #30 & 86 (hot all times).
Check if you get ground @ terminal #85 when you press the horn button.
Check if you get power to terminal #87 when you press the horn button.
Test that the horns are grounded.

Have you bench tested the horn/s? Before you go any further, test the horn/s first and make sure they work. Keep us posted.

Tony