In Reply to: Re: Headlights Ground Wire posted by Robert Angney on March 24, 2020 at 10:09:48:
The first step is to assure that there is a proper electrical path from the ground (OEM +) terminal of the battery to the headlamp housing.
The return (ground) path is through the headlamp housing, mounting stud, hood, etc.
A one wire system will NOT work properly without good electrical connections between battery and lamp bulb.
Assuring such good connections can be challenging on decades old machinery, and is one reason why I run separate ground wires.