1995 Chevy Suburban tail lights - brake lights only

if you have no brake lights but the third brake light works and the blinkers work then either you have a bad brake light switch. the switch has 2 outputs on it, one for the third brake light and the other wire feeds the directional switch. so check white wire from brake light switch where it feeds into the bottom of steering column at the directional switch plug, if you have power on the white wire there when the brakes are applied then the directional switch is the problem causing the brake lights not to work.