Running Tail Lights don't work?

[SHEPP2]

Hello, Need some help Buick family. I have no running tail lights. Yes the fuse is good just replaced with new brake switch. Turn single lights work,hazard lights all blink fine I also removed the brake switch and all rear brake lights light up all three. I can't figure out what's next Any help is well appreciated thanks in advance

 

[salvageV6]

Do the front marker lights work when you turn on the tail lamps?
If the front lamps work with the switch and the back don't check the brown wire in the 6 cavity harness connector in the trunk LH rear corner.

 

[1986 Buick GX1]

I had the multi pin connector on top the steering column under the dash come loose. It seems the taillight wire was towards the top end of the connector. It was in ‘88 or so and a bit foggy. lol