Main fuse white wire

I've been trying to fix up this 1979 kz650 sr.
Every time I switch the bugger on I'd blow the fuse to the white wire.
after tracing it around I found it was linked to the brown wires (hours of wiring diagram study)
turns out it was my warning light self checker that is fried!
I unplugged it and lo! no more fried fuse.

Does your tachometer have a brake indicator/warning light? That switch may function to flash the brake indicator/warning light to let you know if there's a problem with the brake light to minimize the chances of getting rear ended.

It does, I don't know if it works or not.
I unplugged this little box and the short stopped.