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Locking Rear Axle
Your vehicle may have this feature. The locking
rear axle can give your vehicle additional traction
from the rear wheels when traveling in off-road
situations such as mud, snow, sand, steep
hills and uneven terrain.
The button used to turn
this feature on or off is
located to the right
of the transfer case
buttons on the center of
the instrument panel.
To lock the rear axle, do the following:
1. Place the transfer case in the 4LO Lock mode.
This is the only mode which will allow the rear
axle to lock. SeeFull-Time Four-Wheel Drive
on page 111for more information regarding
the transfer case and 4LO Lock mode.
2. Press the button with the vehicle stopped or
moving less than 2 mph (3 km/h).
You must wait for the light in the button to stop
ashing and remain illuminated before the
rear axle is locked.Notice:If you try to lock the rear axle while
your vehicle is stuck and the tires are spinning,
you could damage your vehicle’s drivetrain.
The repairs would not be covered by your
warranty. Always lock the rear axle before
attempting situations and/or navigating terrain
which could possibly cause the vehicle to
become stuck.
The locking rear axle will be disengaged when the
wheel speed is greater than 20 mph (32 km/h),
if the vehicle’s battery is low and/or the transfer
case is shifted out of 4LO Lock mode.
Notice:If you lock the rear axle while driving
on pavement, you could damage your vehicle’s
drivetrain. The repairs would not be covered by
your warranty. Do not use the locking rear axle
on pavement. If you need four-wheel drive when
traveling on pavement, use only 4HI.
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StabiliTrak®System
Your vehicle has a vehicle stability enhancement
system called StabiliTrak®. It is an advanced
computer controlled system that assists you with
directional control of the vehicle in difficult
driving conditions.
StabiliTrak
®activates when the computer senses
a discrepancy between your 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 you rst start your vehicle and begin to drive
away, the system performs several diagnostic
checks to insure there are no problems. You may
hear or feel the system working. This is normal and
does not mean there is a problem with your vehicle.
If there is a problem detected with StabiliTrak
®,
a SERVICE STAB SYS message will be displayed
on the Driver Information Center (DIC). See
DIC Warnings and Messages on page 196for
more information. When this message is displayed,
the system is not operational. Adjust your driving
accordingly.StabiliTrak
®comes on automatically whenever you
start your vehicle. However, when the transfer
case is placed in Four-Wheel-Low Lock mode,
StabiliTrak
®is automatically disabled. See
Full-Time Four-Wheel Drive on page 111for more
information. To help assist you with directional
control of the vehicle, you should always leave the
system on. You can turn StabiliTrak
®off if you
ever need to using the TC (traction control) on/off
button. If you press and hold the TC button for
ve seconds, the StabiliTrak
®system and
the traction control system will turn off. When this
is done, the STAB SYS OFF message will be
displayed on the DIC. Press the TC button again
to turn StabiliTrak
®back on. SeeTraction
Control System (TCS) on page 241.
If your vehicle is in cruise control when the
StabiliTrak
®activates, the cruise control will
automatically disengage. When road conditions
allow you to safely use it again, you may reengage
the cruise control. See “Cruise Control on
page 159for more information.
244

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. You can avoid these problems by
braking — if you can stop in time. But sometimes
you cannot; there is not room. That is the time for
evasive action — steering around the problem.
Your vehicle can perform very well in emergencies
like these. First apply your brakes. SeeBraking
on page 238. It is better to remove as much speed
as you can from a possible 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 you are holding the
steering wheel at the recommended 9 and
3 o’clock positions, you can turn it 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.
246

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 may not realize the
surface is slippery until your 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 Anti-Lock Brake System (ABS)
helps avoid only the braking skid.
Off-Road Driving
This off-road guide is meant to provide advice
for when you drive your vehicle off paved roads.
Also, seeBraking on page 238.
Off-road driving can be great fun. But it does have
some denite hazards. The greatest of these is
the terrain itself.
“Off-roading” means you have left the great
North American road system behind. Traffic
lanes are not marked. Curves are not banked.There are no road signs. Surfaces can be slippery,
rough, uphill or downhill. In short, you have
gone right back to nature.
Off-road driving involves some new skills. And
that is why it is very important that you read
this guide. You will nd many driving tips and
suggestions. These will help make your off-road
driving safer and more enjoyable.
Before You Go Off-Roading
There are some things to do before you go out.
For example, be sure to have all necessary
maintenance and service work done. Check to
make sure all underbody shields are properly
attached. Make sure any equipment you
may need — rst aid kit, cell phone, ashlight,
etc. — is securely stored in the vehicle.
Be sure you read all the information about your
four-wheel-drive vehicle in this manual. Is
there enough fuel? Is the spare tire fully inated?
Are the uid levels up where they should be?
What are the local laws that apply to off-roading
where you will be driving? If you do not know, you
should check with law enforcement people in
the area. Will you be on someone’s private land?
If so, be sure to get the necessary permission.
250

Environmental Concerns
Off-road driving can provide wholesome and
satisfying recreation. However, it also raises
environmental concerns. We recognize these
concerns and urge every off-roader to follow
these basic rules for protecting the environment:
Always use established trails, roads, and
areas that have been specially set aside
for public off-road recreational driving; obey
all posted regulations.
Avoid any driving practice that could damage
the environment — shrubs, owers, trees,
grasses — or disturb wildlife. This includes
wheel-spinning, breaking down trees, or
unnecessary driving through streams or over
soft ground.
Always carry a litter bag — make sure all
refuse is removed from any campsite
before leaving.
Take extreme care with open res (where
permitted), camp stoves, and lanterns.
Never park your vehicle over dry grass or
other combustible materials that could
catch re from the heat of the vehicle’s
exhaust system.
Traveling to Remote Areas
It makes sense to plan your trip, especially when
going to a remote area. Know the terrain and
plan your route. You are much less likely to
get bad surprises. Get accurate maps of trails
and terrain. Try to learn of any blocked or
closed roads.
It is also a good idea to travel with at least one
other vehicle. If something happens to one
of them, the other can help quickly.
Does your vehicle have a winch? If so, be sure
to read the winch instructions. In a remote area,
a winch can be handy if you get stuck. But you
will want to know how to use it properly.
High Mobility Characteristics
The HUMMER H3 has a 10 inch (25.4 cm)
running ground clearance (A) and a 9 inch
(22.8 cm) axle to ground clearance (B) while
maintaining a low silhouette and a low center
of gravity.
252

Your 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 FIRST (1) 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 will not operate
if the brakes are applied, even slightly.
4. If wheel spin cannot be controlled by the
system, fully press the brake pedal with
your left foot so all wheel spin is halted.
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.
255

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 FIRST (1) 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-road driving does require some
new and different skills. Here is what we mean.
Tune your senses to different kinds of signals.
Your eyes, for example, need to constantly sweep
the terrain for unexpected obstacles. Your ears
need to listen for unusual tire or engine sounds.
With your arms, hands, feet and body, you will
need to respond to vibrations and vehicle bounce.
Controlling your vehicle is the key to successful
off-road driving. One of the best ways to control
your vehicle is to control your speed. Here are
some things to keep in mind. At higher speeds:
You approach things faster and you have
less time to scan the terrain for obstacles.
You have less time to react.
You have more vehicle bounce when you
drive over obstacles.
You will need more distance for braking,
especially since you are on an unpaved
surface.
256

Roll Your Tires Over Large Rocks
Do not straddle large
rocks; drive over them,
letting the tire cover
the rock. The tread of
the tire is thicker
and tougher than the
sidewall of the tire
and is more resilient to
impact than underbody
components.
Log Crossing
Using the proper technique, your vehicle will
cross logs up to 10 inches (25.4 cm) in diameter.
Approach the log at approximately a 15 degree
angle (A) with the transmission in FIRST (1)
and the transfer case in Four-Wheel-Low Lock
and “walk” your vehicle over, one tire at a time.
It may be necessary to modulate your brake
pedal and accelerator to avoid spin-out. Ease
the vehicle down from the log with your brake.
259

Driving on Off-Road Hills
Off-road driving often takes you up, down, or
across a hill. Driving safely on hills requires good
judgment and an understanding of what your
vehicle can and cannot do. There are some hills
that simply cannot be driven, no matter how
well built the vehicle.
{CAUTION:
Many hills are simply too steep for any
vehicle. If you drive up them, you will
stall. If you drive down them, you cannot
control your speed. If you drive across
them, you will roll over. You could be
seriously injured or killed. If you have
any doubt about the steepness, do not
drive the hill.
Approaching a Hill
When you approach a hill, you need to decide if it
is one of those hills that is just too steep to climb,
descend, or cross. Steepness can be hard to judge.
On a very small hill, for example, there may be a
smooth, constant incline with only a small change in
elevation where you can easily see all the way to
the top. On a large hill, the incline may get steeper
as you near the top, but you may not see this
because the crest of the hill is hidden by bushes,
grass, or shrubs.
Here are some other things to consider as you
approach a hill:
Is there a constant incline, or does the hill get
sharply steeper in places?
Is there good traction on the hillside, or will
the surface cause tire slipping?
Is there a straight path up or down the hill so
you will not have to make turning maneuvers?
Are there obstructions on the hill that can
block your path, such as boulders, trees, logs,
or ruts?
260

If your engine has stopped running, you will
need to restart it. With the brake pedal
pressed, apply the parking brake. If you
have an automatic transmission, shift the
transmission to PARK (P). Restart the engine.
Then, shift to REVERSE (R), release the
parking brake, and slowly back down the hill
as straight as possible in REVERSE (R).
As you are backing down the hill, put your
left hand on the steering wheel at the
12 o’clock position. This way, you will be
able to tell if your wheels are straight
and maneuver as you back down. It is
best that you back down the hill with your
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.Here are some things youmust notdo if you stall,
or are about to stall, when going up a hill:
Never attempt to prevent a stall by shifting
into NEUTRAL (N) to rev-up the engine
and regain forward momentum. This will
not work. Your vehicle will roll backwards very
quickly and you could go out of control.
Instead, apply the regular brake to stop the
vehicle. Then apply the parking brake. Shift to
REVERSE (R), release the parking brake,
and slowly back straight down.
Never attempt to turn around if you are
about to stall when going up a hill. If the hill
is steep enough to stall your vehicle, it is steep
enough to cause you to roll over if you turn
around. If you cannot make it up the hill,
you must back straight down the hill.
263