so you checked the voltage at the plug ands it was in spec- regulator good. if you checked between the black wire at the plug, then its all good to the switch. on the switch side of the plug, measure between the yellow/red wire and yellow wire with switch on high, and yellow/red and green wire for low beam with switch on low. yellow/red and blue for tail wit switch in high or low. that will test switch good/bad. also check the plugs on the frame behind the front shocks- could've been forgotten. if you're not getting ground at the headlight, then you need to check the frame ground, but i can't remember where it is.