Morning all. I have 48 Ford coupe. It's still 6 volt. Passenger side tail light. When only the tail light wire is connected with bulb installed power comes back thru the unplugged brake light wire of the tail light housing. Bulb won't light unless brake light wire is connected. Bulb only lights up on tail light side of bulb even when applying the brake.
Look closely at the bulb - one filament possibly has dropped onto the other causing the feedback. It happens once in a while.
Yep, what 302GMC said, had the same problem with an OT vehicle.. Stop tail bulb had a broken tail light fillament which had fallen across the brake light filament..
Probably ground issues with tail light housing. 6 volts are really touchy with the grounds.I had a similar problem with the '50 Chevy, I installed a lead wire from my offending tail light housing for a ground to the body, works fine. You may see if you have rust causing it not to get a proper ground.
DC voltage runs in a circular motion in your auto + to - or -to+ depending on if you have pos or neg ground system . The current flows through the bulb and back to ground . If there is a bad ground or wires touching current goes to least resistance to return to the battery , this is where the term “ short circuit “ comes from . The current is not completing the designed path of flow through the bulb correctly it finding the easiest path to ground through the remaining element to ground . Damn . I hope this makes it easier to understand . Just get yourself a good clean ground and it will cure itself .
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