The l/h brake light has no power to the socket. All fuse's are good. Any ideas?

When the brake lamp switch is closed (and the other brake lamps are lit), there should be battery voltage on the G-W wire leading to all the brake lamp sockets.
They all share redundant common ground points in separate locations.
(see schematics)
If you're not getting power to only the L/H brake lamp socket, there is an open circuit between the socket and the splice that shares power to all the other lamps on that circuit.

Attachment 41230