Since you have a voltage regulator you don't need the "fld" wire to the light switch.
Leave regulator "FLD" connected to generator "F", and disconnect yellow wire, and tape it out of the way.
You COULD run a new, heavier wire from the "L" terminal to the terminal on the light switch that is now powered from the Ammeter, bu it's not really necessary. (Likely, the existing wire that was only intended to handle field current isn't heavy enough to to carry the lighting current.)
IMHO, the only reason to CONSIDER connecting the "L" wire to supply the light switch would be if you plan to run it for many hours at a time with the lights on.
As it left the factory, with a cutout, instead of a VR, the lights would have worked just fine wired as they are.
Leave regulator "FLD" connected to generator "F", and disconnect yellow wire, and tape it out of the way.
You COULD run a new, heavier wire from the "L" terminal to the terminal on the light switch that is now powered from the Ammeter, bu it's not really necessary. (Likely, the existing wire that was only intended to handle field current isn't heavy enough to to carry the lighting current.)
IMHO, the only reason to CONSIDER connecting the "L" wire to supply the light switch would be if you plan to run it for many hours at a time with the lights on.
As it left the factory, with a cutout, instead of a VR, the lights would have worked just fine wired as they are.
