I am resurrecting a 1984 R80 G/S that sat for about 10 years. The previous owner died unexpectedly, so I don't have information on what issues the bike was having when he left our planet. My tail lights weren't working when the bike was running. I checked the fuses located under the tank. I saw in a schematic in my Clymer's book (page 780) that the solid gray wire should leave the ignition switch and go to that fuse. From there, two wires that are gray with black stripes exit. One goes to the tail light, and the other goes to the parking lamp and instrument lights. What is odd to me is that the schematic shows that the gray wire will only be "hot" when the switch is in the parking light position, but not the running (fully on) position. Well low and behold that is exactly how mine works. The tail light is lit in the parking light position, then promptly goes out when I turn the key fully on, but the headlight works just fine -- both high and low beam. I looked at some other schematics, and see that some other models have a headlight relay, and a gray wire comes off of it, and heads to the fuse box. That makes sense to me. But my model doesn't have a headlight relay, or a second gray wire going to the fuse. I can't figure how the tail light is ever to be on when in the regular running mode if my ignition switch is right, and the wiring schematic is right.
A friend tells me that a simple diode from the yellow (headlight) wire to the gray wire will correct the problem, but I'm still mystified on how the system was designed to work, if that pretty Clymer's schematic is correct.
Has anyone dealt with this problem, or know how it should work?
Thanks very much for reading.