I have a 97 1500 Silverado here with a weird brake light problem. The brake light works when the brake pedal is lightly pressed down, but when you press down harder the brake light shuts off. There are no blown fuses, have checked multiple times. The brake switch has been replaced and then both the new one and the old one were checked and good based on a multimeter. This is a frustrating one. We were thinking maybe relay switches, but swapped a couple of those out and still the same thing. Disasembled the tail lights and nothing going bad back there. When I press down lightly on the brake, I can hear the switch turn on and then when I continue to press down, I can hear the switch turn off. What's the deal? Please help!!![/align]

 

check for voltage coming out of the switch when you press the pedal hard. If it is good there then a wire is chaffed or broken somewhere and is moving with the brake pedal. the stop light switch is just an on\off witch so it really shouldn't matter how hard you step on the brakes

 

also make sure it was adjusted ,there is usually some to be done .