brake GMC ENVOY 2009 Owner's Guide

Braking
SeeBrake System Warning Light on page 3-35.
Braking action involves perception time and reaction
time. Deciding to push the brake pedal is perception
time. Actually doing it is reaction time.
Average reaction time is about three-fourths of
a second. But that is only an average. It might be less
with one driver and as long as two or three seconds
or more with another. Age, physical condition, alertness,
coordination, and eyesight all play a part. So do
alcohol, drugs, and frustration. But even in three-fourths
of a second, a vehicle moving at 60 mph (100 km/h)
travels 66 feet (20 m). That could be a lot of distance in
an emergency, so keeping enough space between
the vehicle and others is important.
And, of course, actual stopping distances vary greatly
with the surface of the road, whether it is pavement or
gravel; the condition of the road, whether it is wet, dry, or
icy; tire tread; the condition of the brakes; the weight of
the vehicle; and the amount of brake force applied.Avoid needless heavy braking. Some people drive
in spurts — heavy acceleration followed by heavy
braking — rather than keeping pace with traffic. This is a
mistake. The brakes might not have time to cool between
hard stops. The brakes will wear out much faster with a
lot of heavy braking. Keeping pace with the traffic and
allowing realistic following distances eliminates a lot of
unnecessary braking. That means better braking and
longer brake life.
If the engine ever stops while the vehicle is being driven,
brake normally but do not pump the brakes. If the brakes
are pumped, the pedal could get harder to push down.
If the engine stops, there will still be some power brake
assist but it will be used when the brake is applied. Once
the power assist is used up, it can take longer to stop and
the brake pedal will be harder to push.
Adding non-dealer/non-retailer accessories can affect
vehicle performance. SeeAccessories and Modifications
on page 5-3.
4-4

Antilock Brake System (ABS)
This vehicle has the Antilock Brake System (ABS), an
advanced electronic braking system that will help
prevent a braking skid.
When the engine is started and the vehicle begins to
drive away, ABS checks itself. A momentary motor or
clicking noise might be heard while this test is going on.
This is normal.
If there is a problem with
ABS, this warning light
stays on. SeeAntilock
Brake System (ABS)
Warning Light on
page 3-36.
Along with ABS, the vehicle has a Dynamic Rear
Proportioning (DRP) system. If there is a DRP problem,
both the brake and ABS warning lights come on
accompanied by a 10-second chime. The lights and
chime will come on each time the ignition is turned on
until the problem is repaired. See your dealer/retailer
for service.Let us say the road is wet and you are driving safely.
Suddenly, an animal jumps out in front of you. You slam
on the brakes and continue braking. Here is what
happens with ABS:
A computer senses that the wheels are slowing down.
If one of the wheels is about to stop rolling, the computer
will separately work the brakes at each front wheel
and at both rear wheels.
ABS can change the brake pressure to each wheel, as
required, faster than any driver could. This can help
the driver steer around the obstacle while braking hard.
As the brakes are applied, the computer keeps
receiving updates on wheel speed and controls braking
pressure accordingly.
Remember: ABS does not change the time needed to get
a foot up to the brake pedal or always decrease stopping
distance. If you get too close to the vehicle in front of you,
there will not be enough time to apply the brakes if that
vehicle suddenly slows or stops. Always leave enough
room up ahead to stop, even with ABS.
4-5

Using ABS
Do not pump the brakes. Just hold the brake pedal
down rmly and let antilock work. The brakes might
vibrate or some noise might be heard, but this is normal.
Braking in Emergencies
ABS allows the driver to steer and brake at the same
time. In many emergencies, steering can help more than
even the very best braking.
Brake Assist
This vehicle has a Brake Assist feature designed to
assist the driver in stopping or decreasing vehicle speed
in emergency driving conditions. This feature uses the
stability system hydraulic brake control module to
supplement the power brake system under conditions
where the driver has quickly and forcefully applied the
brake pedal in an attempt to quickly stop or slow down
the vehicle. The stability system hydraulic brake control
module increases brake pressure at each corner of the
vehicle until the ABS activates. Minor brake pedal
pulsations or pedal movement during this time is normal
and the driver should continue to apply the brake pedal
as the driving situation dictates The Brake Assist feature
will automatically disengage when the brake pedal is
released or brake pedal pressure is quickly decreased.
StabiliTrak®System
The vehicle has the StabiliTrak system which combines
antilock brake, traction and stability control systems and
helps the driver maintain directional control of the vehicle
in most driving conditions.
Traction control activates when the controller senses
wheel spin. StabiliTrak will selectively apply the brakes
and reduce engine torque to help regain traction.
Stability control activates when the controller senses a
discrepancy between the intended path and the direction
the vehicle is travelling. StabiliTrak selectively applies
braking pressure at any one of the vehicle’s brakes to
help guide the vehicle in the intended direction.
When you rst start the vehicle and begin to drive away,
the system performs several diagnostic checks to insure
there are no problems. The system may be heard or felt
while it is working. This is normal and does not mean
there is a problem with the vehicle. If driving conditions
delay system initialization, the STABILITRAK NOT
READY message may be displayed on the Driver
Information Center (DIC). If this is the case, the
vehicle does not need servicing.
For more information on the stability messages, see
DIC Warnings and Messages on page 3-51.
4-6

When the StabiliTrak
system is both on and
actively controlling the
stability of the vehicle, the
StabiliTrak light will blink for
the duration of the event.
The system may be heard or felt while it is working.
This is normal.
The StabiliTrak disable
button is located on the
transmission shift handle.
The StabiliTrak system is automatically disabled in
4LO mode and cannot be turned on until the vehicle is
switched to 2HI, 4HI, or 4AWD.
The StabiliTrak system has three modes of operation:
STABILITRAK ON, TRACTION CONTROL OFF, and
STABILITRAK OFF.
STABILITRAK ON — The vehicle will default to
STABILITRAK ON every time the driver starts the
vehicle. The StabiliTrak light will be off and no DIC
messages will be displayed.TRACTION CONTROL OFF — The driver can modify
the engine speed management system by momentarily
pressing the StabiliTrak button on the transmission shift
handle. The StabiliTrak light will come on and TRACTION
CONTROL OFF will be displayed. For vehicles without
a DIC, the StabiliTrak indicator light will come on.
Momentarily pressing the StabiliTrak button again will
return the system to the STABILITRAK ON mode.
STABILITRAK OFF — The driver can turn off
StabiliTrak by pressing the StabiliTrak button for more
than ve seconds. The StabiliTrak light will come on
and STABILITRAK OFF will be displayed. For vehicles
without a DIC, the StabiliTrak indicator light will
come on. Momentarily pressing the StabiliTrak button
again will return the system to the STABILITRAK
ON mode. See StabiliTrak Off below for more
information.
Traction Control Off
In this mode, stability control and brake-traction control
are functional. Engine speed management will be
modied and the driven wheels can spin more freely.
This can cause the brake-traction control to activate
more frequently. If the controller detects excessive wheel
spin in this mode, the StabiliTrak indicator light may
blink and the STABILITRAK ACTIVE message may be
displayed to warn the driver that damage may occur
to the transfer case.
4-7

StabiliTrak Off
In this mode, both stability control and part of the traction
control system are disabled. The vehicle will still have
brake-traction control, but will not be able to use the
engine speed management system. System noises may
be heard as a result of the brake-traction control coming
on. If the controller detects excessive wheel spin in this
mode, the StabiliTrak indicator light may blink and the
STABILITRAK ACTIVE message may be displayed
to warn the driver that damage may occur to the
transfer case.
It is recommended to leave the system on for normal
driving conditions, but it may be necessary to turn
the system off if the vehicle is stuck in sand, mud, ice orsnow, and you may want to “rock” the vehicle in an
attempt to free it. It may also be necessary to turn off the
system when driving in extreme off-road conditions
where high wheel spin is required. SeeIf Your Vehicle
is Stuck in Sand, Mud, Ice, or Snow on page 4-30
for more information.
When the transfer case is in 4LO, the stability system is
automatically disabled. The StabiliTrak light will come
on and the STABILITRAK OFF message will appear on
the DIC. The StabiliTrak system cannot be turned on
until the vehicle is switched to 2HI, 4HI, or 4AWD.
The following chart describes the StabiliTrak system
events and the corresponding messages and lights that
will be displayed on the instrument panel cluster.
Vehicles with a DIC Vehicles without a DIC Event
StabiliTrak
Indicator LightDIC MessageStabiliTrak
Indicator LightStabiliTrak
Service Light—
Off None Off OffStabiliTrak On mode (System is fully
enabled, but is not actively
controlling vehicle stability).
SolidTraction
Control OffSolid Off Traction Control Off Mode
Solid StabiliTrak Off Solid OffStabiliTrak Off Mode (StabiliTrak
indicator light will ash when system
rst enters this mode).
4-8

Vehicles with a DIC Vehicles without a DIC Event
Blinking StabiliTrak Active Blinking OffStabiliTrak system activates using
engine speed management, brake
traction control, and/or stability
control.
SolidService
StabiliTrakSolid SolidStabiliTrak system is disabled due to
a system fault.
SolidStabiliTrak Not
ReadySolid OffStabiliTrak system is disabled due to
a failure to initialize.
Notice:If the StabiliTrak
®light comes on due to
heavy braking and/or because the traction control
system has been continuously active, do not allow
the wheel(s) of one axle to spin excessively. This
could lead to damage to the transfer case and costly
repairs not covered by the vehicle warranty.
Notice:If the wheel(s) of one axle is allowed to spin
excessively while the StabiliTrak, ABS and brake
warning lights and any relevant DIC messages are
displayed, the transfer case could be damaged. The
repairs would not be covered by the vehicle warranty.
Reduce engine power and do not spin the wheel(s)
excessively while these lights and messages are
displayed.StabiliTrak may activate on dry or rough roads or under
conditions such as heavy acceleration while turning
or abrupt upshifts/downshifts of the transmission. When
this happens, a reduction in acceleration may be noticed,
or a noise or vibration may be heard. This is normal.
If cruise control is being used when the system activates,
the StabiliTrak light will ash and cruise control will
automatically disengage. Cruise control may be
reengaged when road conditions allow. SeeCruise
Control on page 3-10.
4-9

Steering in Emergencies
There are times when steering can be more effective
than braking. For example, you come over a hill and nd
a truck stopped in your lane, or a car suddenly pulls out
from nowhere, or a child darts out from between parked
cars and stops right in front of you. These problems can
be avoided by braking — if you can stop in time. But
sometimes you cannot stop in time because there is no
room. That is the time for evasive action —steering
around the problem.
The vehicle can perform very well in emergencies like
these. First apply the brakes. SeeBraking on page 4-4.
It is better to remove as much speed as possible from a
collision. Then steer around the problem, to the left or
right depending on the space available.
An emergency like this requires close attention and
a quick decision. If holding the steering wheel at the
recommended 9 and 3 o’clock positions, it can be turned
a full 180 degrees very quickly without removing either
hand. But you have to act fast, steer quickly, and just as
quickly straighten the wheel once you have avoided the
object.
The fact that such emergency situations are always
possible is a good reason to practice defensive driving
at all times and wear safety belts properly.
4-11

Off-Road Recovery
The vehicle’s right wheels can drop off the edge of a
road onto the shoulder while driving.
If the level of the shoulder is only slightly below the
pavement, recovery should be fairly easy. Ease off the
accelerator and then, if there is nothing in the way, steer
so that the vehicle straddles the edge of the pavement.
Turn the steering wheel 3 to 5 inches, 8 to 13 cm, (about
one-eighth turn) until the right front tire contacts the
pavement edge. Then turn the steering wheel to go
straight down the roadway.
Passing
Passing another vehicle on a two-lane road can be
dangerous. To reduce the risk of danger while passing:
Look down the road, to the sides, and to crossroads
for situations that might affect a successful pass.
If in doubt, wait.
Watch for traffic signs, pavement markings, and
lines that could indicate a turn or an intersection.
Never cross a solid or double-solid line on your side
of the lane.
Do not get too close to the vehicle you want to
pass. Doing so can reduce your visibility.
Wait your turn to pass a slow vehicle.
When you are being passed, ease to the right.
Loss of Control
Let us review what driving experts say about what
happens when the three control systems — brakes,
steering, and acceleration — do not have enough friction
where the tires meet the road to do what the driver has
asked.
In any emergency, do not give up. Keep trying to steer
and constantly seek an escape route or area of less
danger.
4-12

Skidding
In a skid, a driver can lose control of the vehicle.
Defensive drivers avoid most skids by taking reasonable
care suited to existing conditions, and by not overdriving
those conditions. But skids are always possible.
The three types of skids correspond to the vehicle’s
three control systems. In the braking skid, the wheels are
not rolling. In the steering or cornering skid, too much
speed or steering in a curve causes tires to slip and lose
cornering force. And in the acceleration skid, too much
throttle causes the driving wheels to spin.
If the vehicle starts to slide, ease your foot off the
accelerator pedal and quickly steer the way you want
the vehicle to go. If you start steering quickly enough,
the vehicle may straighten out. Always be ready for
a second skid if it occurs.
Of course, traction is reduced when water, snow, ice,
gravel, or other material is on the road. For safety, slow
down and adjust your driving to these conditions. It is
important to slow down on slippery surfaces because
stopping distance is longer and vehicle control
more limited.
While driving on a surface with reduced traction, try
your best to avoid sudden steering, acceleration, or
braking, including reducing vehicle speed by shifting to
a lower gear. Any sudden changes could cause the tires
to slide. You might not realize the surface is slipperyuntil the vehicle is skidding. Learn to recognize warning
clues — such as enough water, ice, or packed snow on
the road to make a mirrored surface — and slow down
when you have any doubt.
Remember: Any Antilock Brake System (ABS) helps
avoid only the braking skid.
Off-Road Driving
Vehicles with four-wheel drive can be used for off-road
driving. Vehicles without four-wheel drive should not be
driven off-road except on a level, solid surface.
The airbag system is designed to work properly under
a wide range of conditions, including off-road usage.
Always wear your safety belt and observe safe driving
speeds, especially on rough terrain.
Drinking and driving can be very dangerous on any road
and this is certainly true for off-road driving. At the very
time you need special alertness and driving skills, your
reexes, perceptions, and judgment can be affected
by even a small amount of alcohol. You could have a
serious — or even fatal — accident if you drink and drive
or ride with a driver who has been drinking.
Off-roading can be great fun but has some denite
hazards. The greatest of these is the terrain itself. When
off-road driving, traffic lanes are not marked, curves are
not banked, and there are no road signs. Surfaces can be
slippery, rough, uphill, or downhill.
4-13

Attach a ag to the vehicle to be more visible to
approaching traffic on trails or hills.
Sound the horn as you approach the top of the hill
to let opposing traffic know you are there.
Use headlamps even during the day to make the
vehicle more visible to oncoming traffic.
{CAUTION:
Driving to the top (crest) of a hill at full speed can
cause an accident. There could be a drop-off,
embankment, cliff, or even another vehicle. You
could be seriously injured or killed. As you near
the top of a hill, slow down and stay alert.If the vehicle stalls, or is about to stall, and you cannot
make it up the hill:
Push the brake pedal to stop the vehicle and keep it
from rolling backwards and apply the parking brake.
If the engine is still running, shift the transmission to
R (Reverse), release the parking brake, and slowly
back down the hill in R (Reverse).
If the engine has stopped running, you need to
restart it. With the brake pedal pressed and the
parking brake still applied, shift the transmission
to P (Park) and restart the engine. Then, shift to
R (Reverse), release the parking brake, and slowly
back down the hill as straight as possible in
R (Reverse).
While backing down the hill, put your left hand on the
steering wheel at the 12 o’clock position so you can
tell if the wheels are straight and can maneuver as
you back down. It is best to back down the hill with
the wheels straight rather than in the left or right
direction. Turning the wheel too far to the left or right
will increase the possibility of a rollover.
4-19