Hmm. Gotta have 12 volts to make the horn do its thing. Use a pair of jumper wires to connect one of the horns directly to the battery. It should squawk. That will prove the horn is not defective. As for the missing 12 volts, I suppose it is possible there is a second fuse for the horn current, but normally the same circuit is used that makes the relay click. On normal circuits, when the relay clicks, current travels from the battery positive to the horn fuse, to the relay, through the switching contact, through the bulkhead connector on or near the firewall, and to the horn connector. Somewhere along that path there is a break. If you can follow the wires according to their color, work your way back while measuring at various points. You're looking for that missing 12 volts.
Common suspects are corroded or broken wires at the connectors, (unlikely in this case as it would only affect one of the horns), a corroded connector pin at the bulkhead connector, or most likely, pitted relay contacts, particularly if one of the old horns was shorted and drew heavy current.
Monday, May 24th, 2010 AT 6:33 PM