Brake lights on F/R Legacy 340KP

[jwalton022]

My brake lights have stopped working on the aforementioned coach on a diesel Freightliner chassis. I have checked the obvious fuses, switches, and wiring. The Freightliner people mentioned a air line connection through the firewall, but my unit has a sensor through the floor under the petal and is a part of the brake master cylinder (at least that is what I would call this large brass unit with lines going to the wheels.

Any help would be appreciated!