GMC Sierra Classic 2007 Owner's Manual page 515

Brake Wear
Your vehicle has front disc brakes and could have
rear drum brakes or rear 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.
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 605.
If you have rear drum brakes, they do not have
wear indicators, but if you ever hear a rear brake
rubbing noise, have the rear brake linings inspected
immediately. Rear brake drums should be removed
and inspected each time the tires are removed for
rotation or changing. Drum brakes have an
inspection hole to inspect lining wear during
scheduled maintenance. When you have the front
brake pads replaced, have the rear brakes
inspected, too.
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 brakes
adjust for wear.
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