Brake light turning on..??

Ok,i got a 92 Gmc Sierra and every time i hit about 35mph my brake light turns on. I already replaced the brakes, lines, and brake punp and it still turns on. Any ideas to what it could be?

um...........wow....
im at a loss....

try seeing if the brake switch is bad..

Is it full of fluid?

I had the same problem in one of my S-10s...never did figure out what it was...just sold it like that!

theres air in the lines of the abs box you need to bleed it at the master cylinder then the abs box we had this happen when a rear brake cylinder would go out and leak all the fluid out