License Plate light.

[72-Cruiser]

OK, could not get the license plate light to work. Power is supplied when the running lights are turned on. Replaced the unit with a brand new one. It’s a single wire so I am assuming the unit is grounded to the license plate holder. There is power to the bulb but it will not light up. I am stumped.

 

[GandOsDad]

Model, year , pictures perhaps?

 

[EOD Guy]

My guess would be a corroded/broken power wire to the socket or corroded socket to ground. It seems you have ruled out pwr, if you have a multimeter and check continuity between the metal part of the socket body and the vehicle frame..... or I'd take a length of wire strip off approx 3" on insulation and wrap that around the metal part of the socket body and ground the other end.