Chevrolet 2007 TrailBlazer Owner's Manua page 430

Brake Wear
Your vehicle has four-wheel disc brakes.
Disc brake pads have built-in wear indicators that
make a high-pitched warning sound when the
brake pads are worn and new pads are needed.
The sound can come and go or be heard all
the time your vehicle is moving, except when you
are pushing on the brake pedal firmly.
CAUTION:
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The brake wear warning sound means that
soon the brakes will not work well. That
could lead to an accident. When you hear
the brake wear warning sound, have your
vehicle serviced.
Notice: Continuing to drive with worn-out
brake pads could result in costly brake repair.
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Some driving conditions or climates can cause a
brake squeal when the brakes are first applied
or lightly applied. This does not mean something
is wrong with the brakes.
Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated,
inspect brake pads for wear and evenly tighten
wheel nuts in the proper sequence to torque
specifications in Capacities and Specifications
on page 513.
Brake linings should always be replaced as
complete axle sets.
Brake Pedal Travel
See your dealer/retailer if the brake pedal does
not return to normal height, or if there is a rapid
increase in pedal travel. This could be a sign that
brake service might be required.
Brake Adjustment
Every time you make a brake stop, the disc
brakes adjust for wear.