I had the bike sitting for a couple of weeks, went to take her for a ride and the battery was right dead!
Jump started it, rode it for a while and when I parked it and took the key out I noticed the brake light was still on.. D'oh!!
I unplugged the front brake lever sensor, still on
I'm guessing it has to be the rear brake switch
hope it's an easy fix... bike is a 93 katana