Wiring harness for topper

[Flyguy]

Ram 1500, 2017. Have a LEER topper. Using the harness that was in the drivers side taillight assembly. Both the high mounted stop light and the cargo interior light on the topper don't work. Checked the factory installed harness and the ground is good but the red and red/white wires are dead regardless of brake application and of course neither the high mounted stop light nor the light that is mounted inside the topper work. Is there a separate circuit that feeds the factory installed harness?
Appreciate any help you can give.

 

[crash68]

Have a LEER topper

Does your Leer have a box like this on the inside near the lift gate? (ignore the small switch) There are fuses inside that cover for the lights.

Wiring harness to the truck:
Blue/Green - power lock actuator
Black - ground
Red/white - +12V battery power(overhead light power)
Red/black & Red goto the Left and Right turn signals. Both have to have power for the third brake light to illuminate.
This was the "new" style electrical for Leer when I bought it back in '15.
The small switch on the side is for the LED tape lights I added.