Help no brake lights !

I have a 1993 chev 1/2 ton pick up. No brake lights. Fuse is good, bulbs are good. I'm trying to trouble shoot the pedal switch. Can someone tell me if the ignition key should need to be on to have power at the switch and which wires do what according to their color?
Thanks, Bruce

Good basic diagrams at autozone.com, repair guides. Brake lites work, key off on this truck, btw.

Maxwedge, thanks for the tip, the diagrams helped me to fix the problem, I really really apreciate the help.

Good job, thanks for the post back!