Originally Posted by
Cooter
I believe the diode is unrelated. It affects the neutral light and clutch switch.
There is something really wonky going on, and the hunt and peck you've been doing hasn't resolved it (obviously). I'd forget about the fan for a moment. It's time to forget all you have thought so far, get a big, clear copy of the wiring diagram.
Start from the battery positive to the relay/fuse box. Check/trace wiring and test each component in order. By hand, no cheating! It is tedious, but absolutely necessary. It really doesn't take that long and it will find your issue. Guessing hasn't done you any good so far.