Check the wiring. The area that the horn is in (under the raidator on my model) is subject to all kinds of road salt and/or dirt/debris. It is quite possible that the wires have been corroded and they are either grounding themslves or being short circuited by rain water. give them a goo cleaning with simple green or something of that nature and follow the wire leads.

Good luck,

AARON ROCHARD

1976 230.4 W115