3rd Brake light not working

[Texican]

pulled the unit out of liftgate, No power coming from truck.
Lamp functions on bench.
Does it feed from separate fuse or stoplight switch?

 

[Dirt J]

pulled the unit out of liftgate, No power coming from truck.
Lamp functions on bench.
Does it feed from separate fuse or stoplight switch?

Stoplight switch & fuse (15 amp)

 

[Malleus]

All the electrical answers are in the EWD: