2008 GMC ENVOY brake

Brake Wear
Your vehicle has 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 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.Some driving conditions or climates can cause a brake
squeal when the brakes are rst 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 specications in
Capacities and Specifications on page 5-120.
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.
5-40

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 brake parts.
When you replace parts of the braking system — for
example, when the brake linings wear down and you
need new ones put in — be sure you get new approved
replacement parts. If you do not, the brakes might not
work properly. For example, if someone puts in brake
linings that are wrong for your vehicle, the balance
between the 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.
Battery
Your vehicle has a maintenance free battery. When it is
time for a new battery, see your dealer/retailer for
one that has the replacement number shown on the
original battery’s label. SeeEngine Compartment
Overview on page 5-12for battery location.
Warning:Battery posts, terminals, and related
accessories contain lead and lead compounds,
chemicals known to the State of California to cause
cancer and reproductive harm. Wash hands after
handling.
Vehicle Storage
{CAUTION:
Batteries have acid that can burn you and gas
that can explode. You can be badly hurt if
you are not careful. SeeJump Starting on
page 5-42for tips on working around a battery
without getting hurt.
Infrequent Usage: If you drive your vehicle infrequently,
remove the black, negative (−) cable from the battery.
This will help keep the battery from running down.
Extended Storage: For extended storage of your vehicle,
remove the black, negative (−) cable from the battery
or use a battery trickle charger. This will help maintain
the charge of the battery over an extended period
of time.
5-41

Jump Starting
If your vehicle’s battery has run down, you may want to
use another vehicle and some jumper cables to start
your vehicle. Be sure to use the following steps to do it
safely.
{CAUTION:
Batteries can hurt you. They can be dangerous
because:
They contain acid that can burn you.
They contain gas that can explode or
ignite.
They contain enough electricity to
burn you.
If you do not follow these steps exactly, some
or all of these things can hurt you.Notice:Ignoring these steps could result in costly
damage to your vehicle that would not be covered
by your warranty.
Your vehicle cannot be started by pushing or
pulling it, and can be damage by trying it.
1. Check the other vehicle. It must have a 12-volt
battery with a negative ground system.
Notice:If the other vehicle’s system is not a 12-volt
system with a negative ground, both vehicles can
be damaged. Only use vehicles with 12-volt systems
with negative grounds to jump start your vehicle.
2. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles are not touching
each other. If they are, it could cause a ground
connection you do not want. You would not be able
to start your vehicle, and the bad grounding could
damage the electrical systems.
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.
If you have a four-wheel-drive vehicle, be sure
the transfer case is not in NEUTRAL.
5-42

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,
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. SeeInflation - Tire Pressure on
page 5-64.
Curb Weight
: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 4-34.
GAWR FRT
:Gross Axle Weight Rating for
the front axle. SeeLoading Your Vehicle on
page 4-34.
5-61

TPMS Sensor Matching Process
Each TPMS sensor has a unique identication code.
Any time you rotate your vehicle’s tires or replace one or
more of the TPMS sensors, the identication codes will
need to be matched to the new tire/wheel position. The
sensors are matched to the tire/wheel positions in the
following order: driver side front tire, passenger side front
tire, passenger side rear tire, and driver side rear tire
using a TPMS diagnostic tool. See your dealer/retailer for
service.
The TPMS sensors can also be matched to each
tire/wheel position by increasing or decreasing the tire’s
air pressure. If increasing the tire’s air pressure, do not
exceed the maximum ination pressure indicated on the
tire’s sidewall.
To decrease air-pressure out of a tire you can use the
pointed end of the valve cap, a pencil-style air pressure
gage, or a key.
You have two minutes to match the rst tire/wheel
position, and ve minutes overall to match all four
tire/wheel positions. If it takes longer than two minutes, to
match the rst tire and wheel, or more than ve minutes
to match all four tire and wheel positions the matching
process stops and you need to start over.The TPMS sensor matching process is outlined below:
1. Set the parking brake.
2. Turn the ignition switch to ON/RUN with the
engine off.
3. Turn the headlamp control from off to parking lamps
four times within three seconds. A double horn chirp
will sound and the TPMS low tire warning light will
begin to ash. The double horn chirp and ashing
TPMS warning light indicate that the TPMS matching
process has started. The TPMS warning light should
continue ashing throughout the matching
procedure.
4. Start with the driver side front tire.
5. Remove the valve cap from the valve cap stem.
Activate the TPMS sensor by increasing or
decreasing the tire’s air pressure for 10 seconds,
then stop and listen for a single horn chirp. The
single horn chirp should sound within 15 seconds,
conrming that the sensor identication code has
been matched to this tire and wheel position. If you
do not hear the conrming single horn chirp, you will
need to start over with step number one.
6. Proceed to the passenger side front tire, and repeat
the procedure in Step 5.
7. Proceed to the passenger side rear tire, and repeat
the procedure in Step 5.
5-71

You need new tires if any of the following statements
are true:
You can see the indicators at three or more places
around the tire.
You can see cord or fabric showing through the
tire’s rubber.
The tread or sidewall is cracked, cut, or snagged
deep enough to show cord or fabric.
The tire has a bump, bulge, or split.
The tire has a puncture, cut, or other damage that
cannot be repaired well because of the size or
location of the damage.
The rubber in tires degrades over time, even if they are
not being used. This is also true for the spare tire, if
your vehicle has one. Multiple conditions affect how fast
this aging takes place, including temperatures, loading
conditions, and ination pressure maintenance. With
proper care and maintenance tires will typically wear out
before they degrade due to age. If you are unsure about
the need to replace your tires as they get older, consult
the tire manufacturer for more information.
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 near the tire size. 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 5-58for
additional information.
5-74

Vehicles equipped with a tire pressure monitoring
system may give an inaccurate low-pressure
warning if non-TPC spec rated tires are installed
on your vehicle. Non-TPC Spec rated tires may
give a low-pressure warning that is higher or lower
than the proper warning level you would get with
TPC Spec rated tires. SeeTire Pressure Monitor
System on page 5-67.
Your vehicle’s original equipment tires are listed
on the Tire and Loading Information Label. See
Loading Your Vehicle on page 4-34, for more
information about the Tire and Loading Information
Label and its location on your vehicle.
Different Size Tires and Wheels
If you add wheels or tires that are a different size than
your original equipment wheels and tires, this could
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, rollover
airbags, 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 5-74andAccessories
and Modifications on page 5-3for additional information.
5-76

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,
wheel nuts, or Tire Pressure Monitor System (TPMS)
sensors, replace them only with new GM original
equipment parts. This way, you will be sure to have the
right wheel, wheel bolts, wheel nuts, and TPMS sensors
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 5-82for more
information.
Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You cannot know how it has been
used or how far it has been driven. It could fail
suddenly and cause a crash. If you have to
replace a wheel, use a new GM original
equipment wheel.
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