brakes HUMMER H3 2009 User Guide

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. See
Antilock Brake System (ABS)
Warning Light on page 3-28.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 wheel.
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.
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.
Driving Your Vehicle 4-5

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 applythe 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 a vehicle stability
enhancement system called
StabiliTrak. It is an advanced
computer controlled system that
assists the driver with directional
control of the vehicle in difficult
driving conditions.
StabiliTrak activates when the
computer senses a discrepancy
between the intended path and the
direction the vehicle is actually
traveling. StabiliTrak selectively
applies braking pressure at any one
of the vehicle’s brakes to assist
the driver with keeping the vehicle
on the intended path.
When the vehicle is started and
begins to move, the system
performs several diagnostic checksto 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 cruise control is being used when
StabiliTrak activates, the cruise
control automatically disengages.
The cruise control can be
re-engaged when road conditions
allow. SeeCruise Control on
page 3-9.
If there is a problem detected with
StabiliTrak, a SERVICE STAB
SYS message displays on the Driver
Information Center (DIC). See
DIC Warnings and Messages on
page 3-37for more information.
When this message is displayed, the
system is not working. Adjust your
driving accordingly.
StabiliTrak comes on automatically
whenever the vehicle is started
and resets itself at each ignition
cycle. However, when the transfer
case is placed in Four-Wheel-Low
Lock mode, StabiliTrak is
4-6 Driving Your Vehicle

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 4-3. 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.
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.
Driving Your Vehicle 4-11

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.
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.
Remember: Any traction control
system helps avoid only the
acceleration skid. If the traction
system is off, then an acceleration
skid is best handled by easing
your foot off the accelerator pedal.
SeeTraction Control System
(TCS) on page 4-7andStabiliTrak
®
System on page 4-6.
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.
4-12 Driving Your Vehicle

The vehicle should be able to
traverse a 40% (22 degrees) side
slope at 6 mph (9.7 km/h) while fully
loaded on high friction surfaces.The vehicle can climb a
16 inch (40.6 cm) vertical step.
Step climbing is best done by
approaching the step at an angle
rather than straight on.
Brake and Accelerator
Operation Techniques for
Off-Road Driving
For logs, walls, rocks, severe
ditches, hills, sand, etc.
1. Bring the vehicle to a complete
stop. Do not rev the engine.
2. Select the proper transmission
and transfer case gear
range; usually 1 (First) gear,
Four-Wheel-Low Lock for such
obstacles.3. If wheel spin is experienced,
maintain steady throttle, with
your foot off the brake pedal, to
allow the Traction Control
System (TCS) to control the
wheel spin. TCS might not
operate if the brakes are applied.
4. If wheel spin cannot be controlled
by the TCS system, fully press
the brake pedal with your left foot
so all wheel spin is stopped.
5. Back away from the obstacle
so that a new approach can
be tried.
6. As the rst wheel crosses the
obstacle, be prepared to
alternate the brake and
accelerator pedal to maintain
control and avoid tire drop-off
from obstacles. Repeat this
process for the other wheels.
Driving Your Vehicle 4-17

For mounds, washouts, loose
up-hill slopes, ditches, etc.
When wheel spin occurs as the
vehicle is moving, the driver may
notice a slight shaking or shuddering
of the vehicle. This should be
stopped as soon as possible to
prevent damage to vehicle
components. This is the indication
that a loss of traction is occurring on
this terrain. The operator should:
1. Reduce speed and apply
the brakes.
2. Assess the terrain properly and
adjust vehicle speed and gear
ranges accordingly: Four-Wheel
High position for higher speeds
and Four-Wheel-Low Lock
for more torque and lower
speeds. Transmission 1 (First)
gear is generally recommended.3. Apply slight pressure to the
brake when the shaking or
shuddering sensation is felt,
keeping the vehicle moving in a
controlled manner.
4. Be prepared to alternate between
braking and accelerating through
the adverse terrain.
Getting Familiar with Off-Road
Driving
It is a good idea to practice in an
area that is safe and close to home
before you go into the wilderness.
Off-roading requires some new
and different skills.
Tune your senses to different
kinds of signals. Your eyes need
to constantly sweep the terrain
for unexpected obstacles. Your ears
need to listen for unusual tire or
engine sounds. Use your arms,
hands, feet, and body to respond to
vibrations and vehicle bounce.Controlling the vehicle is the key to
successful off-road driving. One of
the best ways to control the
vehicle is to control the speed.
At higher speeds:
You approach things faster and
have less time to react.
There is less time to scan the
terrain for obstacles.
The vehicle has more bounce
when driving over obstacles.
More braking distance is needed,
especially on an unpaved surface.
{CAUTION
When you are driving off-road,
bouncing and quick changes in
direction can easily throw you
out of position. This could cause
you to lose control and crash.
So, whether you are driving
on or off the road, you and
your passengers should wear
safety belts.
4-18 Driving Your Vehicle

Driving Downhill
When off-roading takes you
downhill, consider:
How steep is the downhill? Will I
be able to maintain vehicle
control?
What is the surface like?
Smooth? Rough? Slippery?
Hard-packed dirt? Gravel?
Are there hidden surface
obstacles? Ruts? Logs?
Boulders?
What is at the bottom of the hill?
Is there a hidden creek bank or
even a river bottom with large
rocks?
If you decide you can go down a hill
safely, try to keep the vehicle
headed straight down. Use a low
gear so engine drag can help
the brakes so they do not have to
do all the work. Descend slowly,
keeping the vehicle under control at
all times.
{CAUTION
Heavy braking when going down
a hill can cause your brakes to
overheat and fade. This could
cause loss of control and a
serious accident. Apply the brakes
lightly when descending a hill and
use a low gear to keep vehicle
speed under control.
Things not to do when driving down
a hill:
When driving downhill, avoid
turns that take you across
the incline of the hill. A hill that
is not too steep to drive down
might be too steep to drive
across. The vehicle could
roll over.
Never go downhill with the
transmission in N (Neutral), called
free-wheeling. The brakes will
have to do all the work and could
overheat and fade.Vehicles are much more likely to
stall when going uphill, but if it
happens when going downhill:
1. Stop the vehicle by applying the
regular brakes and apply the
parking brake.
2. With an automatic transmission,
shift to P (Park). While still
braking, restart the engine.
3. Shift back to a low gear, release
the parking brake, and drive
straight down.
4. If the engine will not start, get
out and get help.
4-24 Driving Your Vehicle

Driving in Water
{CAUTION
Driving through rushing water can
be dangerous. Deep water can
sweep your vehicle downstream
and you and your passengers
could drown. If it is only shallow
water, it can still wash away the
ground from under your tires, and
you could lose traction and roll
the vehicle over. Do not drive
through rushing water.
Heavy rain can mean ash ooding,
and ood waters demand extreme
caution.Find out how deep the water is
before driving through it. Do not
try it if it is deep enough to cover
the wheel hubs, axles, or exhaust
pipe — you probably will not get
through. Deep water can damage the
axle and other vehicle parts. The
vehicle is capable of depths up to
20 inches (50 cm). Know how to
judge whether the water is deeper
than this before proceeding into it.
If the water is not too deep, drive
slowly through it. At faster speeds,
water splashes on the ignition
system and the vehicle can stall.
Stalling can also occur if you get the
tailpipe under water. If the tailpipe
is under water, you will never
be able to start the engine. When
going through water, remember that
when the brakes get wet, it might
take longer to stop. SeeDriving
in Rain and on Wet Roads on
page 4-29.
After Off-Road Driving
Remove any brush or debris that
has collected on the underbody,
chassis, or under the hood. These
accumulations can be a re hazard.
After operation in mud or sand,
have the brake linings cleaned and
checked. These substances can
cause glazing and uneven braking.
Check the engine and oil coolers
for mud accumulation. Thoroughly
and carefully clean these devices to
allow proper cooling. Check the
body structure, steering, suspension,
wheels, tires, and exhaust system
for damage and check the fuel lines
and cooling system for any
leakage.
The vehicle requires more frequent
service due to off-road use.
Refer to the Maintenance Schedule
for additional information.
Driving Your Vehicle 4-27

Driving in Rain and on
Wet Roads
Rain and wet roads can reduce
vehicle traction and affect your
ability to stop and accelerate.
Always drive slower in these types
of driving conditions and avoid
driving through large puddles and
deep-standing or owing water.
{CAUTION
Wet brakes can cause crashes.
They might not work as well in a
quick stop and could cause
pulling to one side. You could
lose control of the vehicle.
After driving through a large
puddle of water or a car/vehicle
wash, lightly apply the brake
pedal until the brakes work
normally.
(Continued)
CAUTION (Continued)
Flowing or rushing water creates
strong forces. Driving through
owing water could cause your
vehicle to be carried away. If this
happens, you and other vehicle
occupants could drown. Do not
ignore police warnings and be
very cautious about trying to drive
through owing water.
Hydroplaning
Hydroplaning is dangerous. Water
can build up under your vehicle’s
tires so they actually ride on
the water. This can happen if the
road is wet enough and you
are going fast enough. When your
vehicle is hydroplaning, it has little or
no contact with the road.
There is no hard and fast rule about
hydroplaning. The best advice is
to slow down when the road is wet.
Other Rainy Weather Tips
Besides slowing down, other wet
weather driving tips include:
Allow extra following distance.
Pass with caution.
Keep windshield wiping
equipment in good shape.
Keep the windshield washer uid
reservoir lled.
Have good tires with proper tread
depth. SeeTires on page 5-44.
Turn off cruise control.
Driving Your Vehicle 4-29

Before Leaving on a
Long Trip
To prepare your vehicle for a long
trip, consider having it serviced
by your dealer/retailer before
departing.
Things to check on your own
include:
Windshield Washer Fluid:
Reservoir full? Windows
clean — inside and outside?
Wiper Blades:In good shape?
Fuel, Engine Oil, Other Fluids:All
levels checked?
Lamps:Do they all work and are
lenses clean?
Tires:Are treads good? Are tires
inated to recommended
pressure?
Weather and Maps:Safe to
travel? Have up-to-date maps?
Highway Hypnosis
Always be alert and pay attention
to your surroundings while driving. If
you become tired or sleepy, nd
a safe place to park your vehicle
and rest.
Other driving tips include:
Keep the vehicle well ventilated.
Keep interior temperature cool.
Keep your eyes moving — scan
the road ahead and to the sides.
Check the rearview mirror and
vehicle instruments often.
Hill and Mountain Roads
Driving on steep hills or through
mountains is different than driving
on at or rolling terrain. Tips for
driving in these conditions include:
Keep the vehicle serviced
and in good shape.
Check all uid levels and brakes,
tires, cooling system, and
transmission.
Going down steep or long hills,
shift to a lower gear.
{CAUTION
If you do not shift down, the
brakes could get so hot that they
would not work well. You would
then have poor braking or even
none going down a hill. You could
crash. Shift down to let the engine
assist the brakes on a steep
downhill slope.
4-30 Driving Your Vehicle