GMC 2007 Acadia - Manual (Page 335)

But you will use it when you brake. Once the
power assist is used up, it can take longer to stop
and the brake pedal will be harder to push.
Adding non-dealer/non-retailer accessories can
affect your vehicle’s performance. See Accessories
and Modifications on page 385.
Anti-Lock Brake System (ABS)
Your vehicle has the Anti-Lock Brake System
(ABS), an advanced electronic braking system that
will help prevent a braking skid.
When you start the engine and begin to drive
away, ABS will check itself. You might hear
a momentary motor or clicking noise while this test
is going on, and you might even notice that the
brake pedal moves a little. This is normal.
If there is a problem
with ABS, this warning
light will stay on.
See Anti-Lock Brake
System Warning
Light on page 223.
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
wheel.
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