brake CHEVROLET EXPRESS 2006 Repair Manual

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. The vehicle
was designed and tested with top-quality brake parts.
When parts of the braking system are replaced — for
example, when the brake linings wear down and new
ones are installed — be sure to get new approved
replacement parts. If this is not done, the brakes might
not work properly. For example, if someone puts in
brake linings that are wrong for the vehicle, the balance
between the front and rear brakes can change — for the
worse. The braking performance expected can change in
many other ways if the wrong replacement brake parts
are installed.
Battery
Refer to the replacement number on the original battery
label when a new battery is needed. SeeEngine
Compartment Overview on page 6-14for battery location.
{DANGER:
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.
6-43

Notice:Ignoring these steps could result in costly
damage to the vehicle that would not be covered
by the warranty.
Trying to start the vehicle by pushing or pulling it
will not work, and it could damage the vehicle.
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 firmly on both vehicles involved
in the jump start procedure. Put an automatic
transmission in P (Park) or a manual transmission
in N (Neutral) before setting the parking brake.
Notice:If you leave the radio or other accessories
on during the jump starting procedure, they could
be damaged. The repairs would not be covered by
the warranty. Always turn off the radio and other
accessories when jump starting the vehicle.
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or the accessory power outlet. Turn off the
radio and all lamps that are not needed. This will
avoid sparks and help save both batteries. And it
could save the radio!
6-45

(D) Construction Code:A letter code is used to
indicate the type of ply construction in the tire. The
letter R means radial ply construction; the letter D
means diagonal or bias ply construction; and the
letter B means belted-bias ply construction.
(E) Rim Diameter
:Diameter of the wheel in
inches.
(F) Load Range
:Load Range.
(G) Service Description
:The service description
indicates the load index and speed rating of a tire.
If two numbers are given as in the example,
120/116, then this represents the load index for
single versus dual wheel usage (single/dual).
The speed rating is the maximum speed a tire is
certified to carry a load. This does not apply to
Goodyear LT225/75R16 G949 RSA and Goodyear
LT225/75R16 G933 RSD commercial truck tires;
see the dual tire and single tire maximum load and
load range letter designations on the tire sidewall.
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.
6-65

TPMS Sensor Matching Process
Each TPMS sensor has a unique identification code.
Any time you rotate your vehicle’s tires or replace one
or more of the TPMS sensors, the identification 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 inflation 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 first tire/wheel
position, and five minutes overall to match all four
tire/wheel positions. If it takes longer than two minutes, to
match the first tire and wheel, or more than five 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. Press the Remote Keyless Entry (RKE) transmitter’s
LOCK and UNLOCK buttons at the same time
for approximately five seconds. The horn sounds
twice to signal the receiver is in relearn mode and
TIRE LEARNING ACTIVE message displays on the
DIC screen.
If your vehicle does not have RKE, press the Driver
Information Center (DIC) vehicle information button
until the PRESS
VTO RELEARN TIRE POSITIONS
message displays. The horn sounds twice to signal
the receiver is in relearn mode and TIRE LEARNING
ACTIVE message displays on the DIC screen.
If your vehicle does not have RKE or DIC buttons,
press the trip odometer reset stem located on the
instrument panel cluster until the PRESS
VTO
RELEARN TIRE POSITIONS message displays.
The horn sounds twice to signal the receiver is in
relearn mode and TIRE LEARNING ACTIVE
message displays on the DIC screen.
6-74

Buying New Tires
GM has developed and matched specific 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 Specification
(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 specifications 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 6-61for additional
information.
GM recommends replacing tires in sets of four (or six
if your vehicle has dual rear wheels). This is because
uniform tread depth on all tires will help keep your vehicle
performing most like it did when the tires were new.
Replacing less than a full set of tires can affect the
braking and handling performance of your vehicle.
SeeTire Inspection and Rotation on page 6-75for
information on proper tire rotation.{WARNING:
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.
{WARNING:
If you use bias-ply tires on the vehicle, the
wheel rim flanges 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 the vehicle.
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.
6-79

Vehicles that have a tire pressure monitoring system
could 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. See
Tire Pressure Monitor System on page 6-70.
Your vehicle’s original equipment tires are listed on the
Tire and Loading Information label. SeeLoading the
Vehicle on page 5-19, 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 electronicsystems such as anti-lock brakes, rollover airbags,
traction control, and electronic stability control, the
performance of these systems can be affected.
{WARNING:
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
specific wheel and tire systems developed for your
vehicle, and have them properly installed by a GM
certified technician.
SeeBuying New Tires on page 6-79andAccessories
and Modications on page 6-3for additional information.
6-80

Your dealer/retailer 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 the 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 the vehicle.
{WARNING:
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.
Whenever a wheel, wheel bolt or wheel nut is replaced
on a dual wheel setup, check the wheel nut torque after
100, 1,000 and 6,000 miles (160, 1 600 and 10 000 km)
of driving. For proper torque, see “Wheel Nut Torque”
underCapacities and Specications on page 6-116.
SeeChanging a Flat Tire on page 6-86for more
information.
Used Replacement Wheels
{WARNING:
Putting a used wheel on the 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.
6-83

Tire Chains
{WARNING:
If your vehicle has dual wheels or P245/70R17 or
LT245/75R16 size tires, do not use tire chains.
They can damage your vehicle because there is not
enough clearance. Tire chains used on a vehicle
without the proper amount of clearance can cause
damage to the brakes, suspension, or other vehicle
parts. The area damaged by the tire chains could
cause you to lose control of your vehicle and you
or others may be injured in a crash.
Use another type of traction device only if its
manufacturer recommends it for use on your
vehicle and tire size combination and road
conditions. Follow that manufacturer’s instructions.
WARNING: (Continued)
WARNING: (Continued)
To help avoid damage to your vehicle, drive
slowly, readjust, or remove the device if it is
contacting your vehicle, and do not spin the
vehicle’s wheels.
If you do find traction devices that will fit, install
them on the rear tires.
Notice:If your vehicle does not have dual wheels
and has a tire size other than P245/70R17 or
LT245/75R16, use tire chains only where legal and
only when you must. Use chains that are the proper
size for your tires. Install them on the tires of the
rear axle. Do not use chains on the tires of the front
axle. Tighten them as tightly as possible with the
ends securely fastened. Drive slowly and follow the
chain manufacturer’s instructions. If you can
hear the chains contacting your vehicle, stop and
retighten them. If the contact continues, slow down
until it stops. Driving too fast or spinning the
wheels with chains on will damage your vehicle.
6-84

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 flat tire creates a drag that pulls
the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel firmly.
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.{WARNING:
Lifting a vehicle and getting under it to do
maintenance or repairs is dangerous without the
appropriate safety equipment and training. If a jack
is provided with the vehicle, it is designed only for
changing a flat tire. If it is used for anything else,
you or others could be badly injured or killed if the
vehicle slips off the jack. If a jack is provided with
the vehicle, only use it for changing a flat tire.
If a tire goes flat, the next part shows how to use the
jacking equipment to change a flat tire safely.
6-85

Changing a Flat Tire
If a tire goes flat, avoid further tire and wheel damage
by driving slowly to a level place. Turn on the hazard
warning flashers. SeeHazard Warning Flashers
on page 4-3.
{WARNING:
Changing a tire can be dangerous. The vehicle
can slip off the jack and roll over or fall on you or
other people. You and they could be badly injured
or even killed. Find a level place to change your
tire. To help prevent the vehicle from moving:
1. Set the parking brake firmly.
2. Put the shift lever in P (Park).
3. Turn off the engine and do not restart while
the vehicle is raised.
4. Do not allow passengers to remain in the
vehicle.
WARNING: (Continued)
WARNING: (Continued)
To be even more certain the vehicle will not move,
you should put blocks at the front and rear of the
tire farthest away from the one being changed.
That would be the tire, on the other side, at the
opposite end of the vehicle.
When the vehicle has a flat tire (B), use the following
example as a guide to assist you in the placement
of wheel blocks (A).
A. Wheel Block
B. Flat Tire
The following information explains how to use the jack
and change a tire.
6-86