1994 Chevy Chevy Silverado 1500 1994 my brake lights won't come on

Did you check for voltage, anywhere, use a test light. The stop fuse is hot all the time, see if any voltage at the fuse. The orange wire at stop lamp switch, hot all the time, check for voltage. From stop lamp switch, yellow wire goes hot when switch is activated, check that. Your hi mount stop lamp doesn't work as well as lower brake lamps? your brake switch is activated by brake pedal arm, follow the arm up to find the stop lamp switch. It appears your lower brake lamps are wired through the turn signal switch. your hi mount stop lamp isn't wired that way.