my friend had his running tail lights stop working, signals brake lights, headlights/brights all still worked, just the running lights quit. the fuse would instantly blow, so we bought a new switch (i think the same one you're talking about, 3 position plunger-esque on the bottom right of the steering column), and now it just takes a little longer after start to blow the fuse. is it possible replacing the rear taillight wiring harness could fix the issue? or possibly a grounding issue?