Chevrolet 2007 TrailBlazer Owner's Manua page 312

Let us say the road is wet and you are driving
safely. Suddenly, an animal jumps out in front of
you. You slam on the brakes and continue braking.
Here is what happens with ABS:
A computer senses that wheels are slowing down.
If one of the wheels is about to stop rolling, the
computer will separately work the brakes at each
front wheel and at both rear wheels.
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ABS can change the brake pressure faster than any
driver could. The computer is programmed to make
the most of available tire and road conditions. This
can help you steer around the obstacle while
braking hard.
As you brake, the computer keeps receiving
updates on wheel speed and controls braking
pressure accordingly.