Hey everyone, I have a 1985 K100 and I'm trying to put a aftermarket tail light with a double element bulb on my bike. The original tail light had one bulb for braking and one as a running light, both were single element bulbs. The aftermarket tail light has a doubled element bulb, with 3 wires, black, red and yellow. I hooked the black to ground, gray/yellow to yellow and the gray/black to red. The light will stay on, but as soon as I hit the brake I blow the no.1 fuse. If I switch the gray/yellow to red and the gray/black to yellow, I just blow the no.2 fuse as soon as I turn the key. Anyone have any suggestions? Besides putting the original light back on......:|

You have a short to ground at the yellow wire to the new tail light.

Could be caued by a short in the bulb holder, incorrect mounted bulb,
wrong bulb to that specific bulb holder.

Try the other wires as grounds.  I'd go with yellow first.

thanks guys i will give that a try.-KT