98 brake lights flickering

[mata1k]

I have a 98 c1500 , whenever I press down on the brake pedal the brake lights sometimes turn on and stops when I press down harder. Happens at different pressures ( every time it’s random ) Reverse, turn signals all work perfectly , checked relays and fuses

 

[JOHNGAAA1]

GROUND

 

[GoToGuy]

If it was gound the turn signal would be affected, as the same power and ground wire is brake filament and turn. Should check the brake switch under dash. Good luck.