Tail light gremlins

[65C10ED]

Can anyone offer suggestions on how I can get my tail lights to work properly? I've made this diagram to explain the problem. Any ideas would be appreciated.

[pjmoreland]

Here are a couple if troubleshooting ideas:

1) Make sure your left tail light & brake light work correctly by themselves. Unplug the light from the truck and connect power directly to the wires to see if you can get the tail light and brake light filaments to light up. If this passes, do the same test, but at the connector where the rear harness enters the cab (I'm not familiar with 1960-66 trucks, so I'm making an assumption that there is a connector there).

2) verify proper function of the turn signal switch. Verify you're getting 12V out of it on the left brake light wire when pressing the brakes.

I have had issues with my brake lights before because my turn signal switch contacts were gummed up. Cleaning them solved the problem.

I have heard of people having problems with reproduction lights that had the wires installed backward from the manufacturer.

[chevyguyase]

Is your right turn signal still on when you're pressing the brake? It seems like you have a turn signal switch issue. Maybe try turning the left turn signal on and press the brake to see if the problem is reversed. Left brake light on and the right is off. I've also seen problems with 1157 bulbs. The glass portion of the bulb separates from the brass and twist the filaments together, but they still look good. That doesn't seem to be the issue here.