brake HUMMER H2 2007 Repair Manual

Brakes
Brake Fluid
Your brake master
cylinder reservoir is
lled with DOT-3 brake
uid. SeeEngine
Compartment Overview
on page 402for the
location of the reservoir.
There are only two reasons why the brake uid
level in the reservoir might go down. The rst
is that the brake uid goes down to an acceptable
level during normal brake lining wear. When new
linings are put in, the uid level goes back up.
The other reason is that uid is leaking out of the
brake system. If it is, you should have your
brake system xed, since a leak means that
sooner or later your brakes will not work well, or
will not work at all.So, it is not a good idea to top off your brake uid.
Adding brake uid will not correct a leak. If you
add uid when your linings are worn, then you will
have too much uid when you get new brake
linings. You should add or remove brake uid,
as necessary, only when work is done on
the brake hydraulic system.
{CAUTION:
If you have too much brake uid, it can
spill on the engine. The uid will burn if
the engine is hot enough. You or others
could be burned, and your vehicle could
be damaged. Add brake uid only when
work is done on the brake hydraulic
system. See “Checking Brake Fluid” in
this section.
Refer to the Maintenance Schedule to determine
when to check your brake uid. SeeScheduled
Maintenance on page 517.
427

Checking Brake Fluid
You can check the brake uid without taking off
the cap.
Look at the brake uid
reservoir. The uid level
should be above MIN.
If it is not, have your
brake system checked to
see if there is a leak.
After work is done on the brake hydraulic system,
make sure the level is above the MIN but not
over the MAX mark.
What to Add
When you do need brake uid, use only DOT-3
brake uid. Use new brake uid from a sealed
container only. SeeRecommended Fluids
and Lubricants on page 528.
Always clean the brake uid reservoir cap and the
area around the cap before removing it. This will
help keep dirt from entering the reservoir.
{CAUTION:
With the wrong kind of uid in the brake
system, the brakes may not work well, or
they may not even work at all. This could
cause a crash. Always use the proper
brake uid.
428

Notice:
Using the wrong uid can badly damage
brake system parts. For example, just a
few drops of mineral-based oil, such
as engine oil, in the brake system can
damage brake system parts so badly that
they will have to be replaced. Do not
let someone put in the wrong kind of uid.
If you spill brake uid on your vehicle’s
painted surfaces, the paint nish can be
damaged. Be careful not to spill brake uid
on your vehicle. If you do, wash it off
immediately. SeeWashing Your Vehicle
on page 495.
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 may come and go or be heard all
the time your vehicle is moving, except when you
are pushing on the brake pedal rmly.
{CAUTION:
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.
429

Some driving conditions or climates may cause a
brake squeal when the brakes are rst applied
or lightly applied. This does not mean something
is wrong with your 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 GM torque
specications.
Brake linings should always be replaced as
complete axle sets.
Brake Pedal Travel
See your dealer 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 of brake trouble.
Brake Adjustment
Every time you make a brake stop, your disc
brakes adjust for wear.
Replacing Brake System Parts
The braking system on a vehicle is complex. Its
many parts have to be of top quality and work well
together if the vehicle is to have really good
braking. Your vehicle was designed and tested
with top-quality GM brake parts. When you replace
parts of your braking system — for example,
when your brake linings wear down and you need
new ones put in — be sure you get new
approved GM replacement parts. If you do not,
your brakes may no longer work properly. For
example, if someone puts in brake linings that are
wrong for your vehicle, the balance between your
front and rear brakes can change — for the worse.
The braking performance you have come to expect
can change in many other ways if someone puts in
the wrong replacement brake parts.
430

To avoid the possibility of the vehicles rolling,
set the parking brake rmly on both vehicles
involved in the jump start procedure. Put
an automatic transmission in PARK (P) or a
manual transmission in NEUTRAL before
setting the parking brake.
Notice:If you leave your radio or other
accessories on during the jump starting
procedure, they could be damaged. The repairs
would not be covered by your warranty.
Always turn off your radio and other
accessories when jump starting your vehicle.
3. Turn off the ignition on both vehicles.
Unplug unnecessary accessories plugged into
the cigarette lighter or accessory power
outlets. Turn off the radio and all lamps that
are not needed. This will avoid sparks
and help save both batteries. And it could
save your radio!4. Open the hoods and locate the positive (+)
and negative (−) terminal locations of the
other vehicle.
Your vehicle has a remote positive (+) jump
starting terminal and a remote negative (−)
jump starting terminal. You should always use
these remote terminals instead of the
terminals on the battery.
The remote positive (+)
terminal is located near
the engine accessory
drive bracket. On some
vehicles, the terminal
may be covered
by a red plastic cover.
To access the
remote positive (+)
terminal, open
the cover, if equipped.
433

Tire Terminology and Denitions
Air Pressure:The amount of air inside the tire
pressing outward on each square inch of the
tire. Air pressure is expressed in pounds
per square inch (psi) or kilopascal (kPa).
Accessory Weight:This means the combined
weight of optional accessories. Some examples
of optional accessories are, automatic
transmission/transaxle, power steering, power
brakes, power windows, power seats, and
air conditioning.
Aspect Ratio:The relationship of a tire’s height
to its width.
Belt:A rubber coated layer of cords that is located
between the plies and the tread. Cords may be
made from steel or other reinforcing materials.
Bead:The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the rim.
Bias Ply Tire:A pneumatic tire in which the plies
are laid at alternate angles less than 90 degrees
to the centerline of the tread.Cold Tire Pressure:The amount of air pressure
in a tire, measured in pounds per square inch
(psi) or kilopascals (kPa) before a tire has built up
heat from driving. SeeInation - Tire Pressure
on page 456.
Curb Weight:This means the weight of a motor
vehicle with standard and optional equipment
including the maximum capacity of fuel, oil, and
coolant, but without passengers and cargo.
DOT Markings:A code molded into the sidewall
of a tire signifying that the tire is in compliance
with the U.S. Department of Transportation (DOT)
motor vehicle safety standards. The DOT code
includes the Tire Identication Number (TIN),
an alphanumeric designator which can also identify
the tire manufacturer, production plant, brand,
and date of production.
GVWR:Gross Vehicle Weight Rating.
SeeLoading Your Vehicle on page 362.
GAWR FRT:Gross Axle Weight Rating for the
front axle. SeeLoading Your Vehicle on page 362.
GAWR RR:Gross Axle Weight Rating for the
rear axle. SeeLoading Your Vehicle on page 362.
453

Buying New Tires
GM has developed and matched specic tires
for your vehicle. The original equipment tires
installed on your vehicle, when it was new,
were designed to meet General Motors Tire
Performance Criteria Specication (TPC spec)
system rating. If you need replacement tires,
GM strongly recommends that you get tires with
the same TPC Spec rating. This way, your vehicle
will continue to have tires that are designed to
give the same performance and vehicle safety,
during normal use, as the original tires.
GM’s exclusive TPC Spec system considers over
a dozen critical specications that impact the
overall performance of your vehicle, including
brake system performance, ride and handling,
traction control, and tire pressure monitoring
performance. GM’s TPC Spec number is molded
onto the tire’s sidewall by the tire manufacturer.
If the tires have an all-season tread design,
the TPC spec number will be followed by a MS,
for mud and snow. SeeTire Sidewall Labeling on
page 449for additional information.{CAUTION:
Mixing tires could cause you to lose control
while driving. If you mix tires of different
sizes, brands, or types (radial and
bias-belted tires) the vehicle may not
handle properly, and you could have a
crash. Using tires of different sizes, brands,
or types may also cause damage to your
vehicle. Be sure to use the correct size,
brand, and type of tires on your vehicle’s
wheels.
{CAUTION:
If you use bias-ply tires on your vehicle,
the wheel rim anges could develop
cracks after many miles of driving. A tire
and/or wheel could fail suddenly, causing
a crash. Use only radial-ply tires with the
wheels on your vehicle.
460

If you must replace your vehicle’s tires with those
that do not have a TPC Spec number, make
sure they are the same size, load range, speed
rating, and construction type (radial and
bias-belted tires) as your vehicle’s original tires.
Your vehicle’s original equipment tires are listed on
the Tire and Loading Information label. This label
is attached to the vehicle’s center pillar (B-pillar).
SeeLoading Your Vehicle on page 362, for
more information about the Tire and Loading
Information label.
Different Size Tires and Wheels
If you add wheels or tires that are a different size
than your original equipment wheels and tires,
this may affect the way your vehicle performs,
including its braking, ride and handling
characteristics, stability, and resistance to rollover.
Additionally, if your vehicle has electronic
systems such as, anti-lock brakes, traction control,
and electronic stability control, the performance
of these systems can be affected.
{CAUTION:
If you add different sized wheels, your
vehicle may not provide an acceptable
level of performance and safety if tires
not recommended for those wheels are
selected. You may increase the chance
that you will crash and suffer serious
injury. Only use GM specic wheel and
tire systems developed for your vehicle,
and have them properly installed by a
GM certied technician.
SeeBuying New Tires on page 460and
Accessories and Modications on page 392for
additional information.
461

Wheel Replacement
Replace any wheel that is bent, cracked, or badly
rusted or corroded. If wheel nuts keep coming
loose, the wheel, wheel bolts, and wheel
nuts should be replaced. If the wheel leaks air,
replace it (except some aluminum wheels,
which can sometimes be repaired). See your
dealer if any of these conditions exist.
Your dealer will know the kind of wheel you need.
Each new wheel should have the same
load-carrying capacity, diameter, width, offset and
be mounted the same way as the one it replaces.
If you need to replace any of your wheels, wheel
bolts, or wheel nuts, replace them only with
new GM original equipment parts. This way,
you will be sure to have the right wheel, wheel
bolts, and wheel nuts for your vehicle.{CAUTION:
Using the wrong replacement wheels,
wheel bolts, or wheel nuts on your vehicle
can be dangerous. It could affect the
braking and handling of your vehicle,
make your tires lose air and make you
lose control. You could have a collision
in which you or others could be injured.
Always use the correct wheel, wheel bolts,
and wheel nuts for replacement.
Notice:The wrong wheel can also cause
problems with bearing life, brake cooling,
speedometer or odometer calibration,
headlamp aim, bumper height, vehicle ground
clearance, and tire or tire chain clearance
to the body and chassis.
SeeChanging a Flat Tire on page 468for more
information.
464

If a Tire Goes Flat
It is unusual for a tire to blowout while you are
driving, especially if you maintain your vehicle’s
tires properly. If air goes out of a tire, it is
much more likely to leak out slowly. But if you
should ever have a blowout, here are a few tips
about what to expect and what to do:
If a front tire fails, the at tire will create a drag
that pulls the vehicle toward that side. Take your
foot off the accelerator pedal and grip the
steering wheel rmly. Steer to maintain lane
position, and then gently brake to a stop well out
of the traffic lane.
A rear blowout, particularly on a curve, acts much
like a skid and may require the same correction
you would use in a skid. In any rear blowout
remove your foot from the accelerator pedal.
Get the vehicle under control by steering the way
you want the vehicle to go. It may be very
bumpy and noisy, but you can still steer. Gently
brake to a stop, well off the road if possible.{CAUTION:
Lifting a vehicle and getting under it to do
maintenance or repairs is dangerous
without the appropriate safety equipment
and training. The jack provided with your
vehicle is designed only for changing a
at tire. If it is used for anything else, you
or others could be badly injured or killed
if the vehicle slips off the jack. Use the
jack provided with your vehicle only for
changing a at tire.
If a tire goes at, the next part shows how to use
the jacking equipment to change a at tire safely.
Changing a Flat Tire
If a tire goes at, avoid further tire and wheel
damage by driving slowly to a level place.
Turn on your hazard warning ashers.
468