Brake light doesn't work with night running lights on

[colins]

Hey All,
I'm having this really weird issue with the left tail light on my '98 C1500 Truck. When the night running lights are switched on, the left brake light and turn signal does not work, but the night running light does work. When the night running lights are switched off the tail lights work normally (brake light, turn signal). The right tail light functions normally in all states.

I have already replaced:

1. Bulbs
2. Tail Light Circuit Board
3. Tail Light Connector Harness

I have also checked the fuses and those are all normal.

Any thoughts? I'm at a loss. Thanks in advance for the help.

[ToyHauler]

try adding extra ground jumper see if that changes it. is this the original problem or did it happen when you changed the housing