Bungled horn install, eating fuses.

[CrankyOldMan]

So my horn install had been working swimmingly, but the shortcut I took with the relay has gone all wrong. I mounted the relay where the horn is installed to make the wiring simpler and wrapped the junction in electrical tape. Well, at some point this winter, the salt and moisture seeped into the relay and corroded all of the contacts together. I went this way with it because I'm using two FIAMM freeway blasters in parallel and had to run a larger gauge wire to the horns.

My first remedy was to change the 10A horn fuse in the engine bay fuse box: turn on car, no honk, burned up the fuse. No worries, there was a spare relay handy: connect relay, replace fuse, turn on car, no honk, burned up the new fuse. The relay was also warm. Strange.

The next step was to try the horns individually with an inline fuse direct from the battery. One horn worked, the other didn't. Time for a continuity test. The DMM showed them as having similar resistances of around 3.4 ohms, so that has me a bit stumped.

Ok, time to get out the repair manual. The diagnostics for the integrated relay box involve hooking some very small pins up to a power supply and DMM. I'm really not sure how to safely clip on to those without a sacrificial dongle, and a replacement is at least $50-60 even from a junk yard.

Anyone have any suggestions of how to proceed from here?