Hey Folks,
New to the forum, just bought a '96 FJZ80, "Metallic Red Pearl", lockers, 73K miles. Truck had been sitting in a condo parking lot for quite some time (found cobwebs, wasps nests (!!) under the hood, no wasps thankfully)
I've been cleaning/detailing under the hood and my OEM horns were pretty rusted and sad looking. I took 'em apart, took the rust off the baseplate, painted it with POR-15 and Chassis Coat Black and bolted it back on with some nice ARP stainless bolts.
Decided to buy Hella Supertones after looking at sorry state of OEM horns. Meanwhile, I had to use old horns until Hellas came and could not get them to work after putting them back on. Hellas arrived and could not get them to work either.
Long story short -- it was a combination of two different issues.
1.) Relay was fine and working (heard clicking when depressing horn); fuse was not melted, but there was some oxidation on fuse contacts, barely noticable. Took it off with a copper wire brush.
2.) POR-15 (anti-rust paint) apparently is not conductive...it's like a hard polyurethane coating. Stainless bolts don't help. Duh. Baseplate is the ground for the 12v circuit, as mentioned above. Hellas each have 2 male connectors, one presumably for power and one for ground if needed; I wired me up some ground cables which I connected from horns to the baseplate.
Dedicated ground wires, plus cleaning the contacts of the fuse, gave me a screaming pair of supertones. Seriously loud! I drove around this morning looking for someone to blast them at...
Check the ground first, then the fuse. My case it was both. Driving in Brooklyn without a horn is a lesson in patience (and not very smart...)
Cheers to all who helped out, great site.