Sorry. Pull out the wiring diagram and start tracing wires. Can't be that hard to find. On my 1981 to 1985 Wiring diagram, the Flash circuit connects the High beam wire to a green wire that gets its power from the ignition switch. Power for the lights normally comes from the headlight relay -- a yellow wire. The flasher circuit bypasses the headlamp relay and directly connects the high beam to a green wire that is always powered. Also connected to this green wire are the coils, the turn signal relay, the tachometer, the charge indicator, the neutral light, and the oil pressure light. So if all that other stuff is working then I would start at the switch and see if that green wire has system voltage and if not then trace it back to under the tank until I found the break. It could be that connector under the tank. Persistance will pay off in the end.
Good luck.
