My anti lock brakes keep coming on when i press the brake pedal about 1 out of every time the pedal vibrates.

this condition is on dry roads sometimes i almost rearend the car in front of me because the anti locks are on

whats making my blazer think the tires are sliding

 

Dirty wheel speed sensors? Too much air gap between the sensor and the tone ring?

This thread will explain how to check things out:
Brakes - Low Speed (below 5 MPH) ABS Activation