HUMMER H3 2007 Owners Manual

Loading Your Vehicle for Off-Road
Driving
{CAUTION:
Cargo on the load oor piled higher
than the seatbacks can be thrown
forward during a sudden stop. You
or your passengers could be injured.
Keep cargo below the top of the
seatbacks.
Unsecured cargo on the load oor can
be tossed about when driving over
rough terrain. You or your passengers
can be struck by ying objects.
Secure the cargo properly.
Heavy loads on the roof raise the
vehicle’s center of gravity, making it
more likely to roll over. You can be
seriously or fatally injured if the
vehicle rolls over. Put heavy loads
inside the cargo area, not on the roof.
Keep cargo in the cargo area as far
forward and low as possible.There are some important things to remember
about how to load your vehicle.
The heaviest things should be on the
load oor and forward of your rear axle.
Put heavier items in the rear area, as far
forward as you can.
Be sure the load is secured properly, so
driving on the off-road terrain does not
toss things around.
You will nd other important information in this
manual. SeeLoading Your Vehicle on page 289
andTires on page 367.
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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.
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The HUMMER H3 has an approximate approach
angle (A) of 37.5 degrees and a departure
angle (B) of 35.5 degrees, depending on
suspension packages.
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Design specications required a minimum
gradeability of 60% (31 degrees) slope, with the
vehicle fully loaded, on high friction surfaces
with maximum vehicle speed not to exceed
6 mph (9.7 km/h). The vehicle is expected to
traverse this grade only for short durations.
Never stop and idle the vehicle or park it on
this grade.Also, your 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.
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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.
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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

{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.
Scanning the Terrain
Off-road driving can take you over many different
kinds of terrain. You need to be familiar with
the terrain and its many different features.
Here are some things to consider.
Surface Conditions:Off-roading can take you
over hard-packed dirt, gravel, rocks, grass, sand,
mud, snow, or ice. Each of these surfaces affects
the steering, acceleration, and braking of your
vehicle in different ways. Depending upon the kind
of surface you are on, you may experience slipping,
sliding, wheel spinning, delayed acceleration,
poor traction, and longer braking distances.Surface Obstacles:Unseen or hidden obstacles
can be hazardous. A rock, log, hole, rut, or bump
can startle you if you are not prepared for them.
Often these obstacles are hidden by grass, bushes,
snow, or even the rise and fall of the terrain itself.
Here are some things to consider:
Is the path ahead clear?
Will the surface texture change abruptly
up ahead?
Does the travel take you uphill or downhill?
There is more discussion of these subjects
later.
Will you have to stop suddenly or change
direction quickly?
When you drive over obstacles or rough terrain,
keep a rm grip on the steering wheel. Ruts,
troughs, or other surface features can jerk
the wheel out of your hands if you are not
prepared.
When possible, it is a good practice to survey
the landscape ahead on foot prior to driving
to observe hidden obstacles.
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When you drive over bumps, rocks, or other
obstacles, your wheels can leave the ground.
If this happens, even with one or two wheels, you
cannot control the vehicle as well or at all.
Because you will be on an unpaved surface, it is
especially important to avoid sudden acceleration,
sudden turns, or sudden braking.
In a way, off-road driving requires a different kind
of alertness from driving on paved roads and
highways. There are no road signs, posted speed
limits, or signal lights. You have to use your
own good judgment about what is safe and
what is not.
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. SeeDrunken Driving on page 235.Crossing Obstacles
Approach Angle — a Key to Mobility
If you encounter a large dip in the terrain, do not
enter straight on; enter at an angle — 15 degrees
minimum approach (A), 75 degrees maximum
approach angle (B). For very large dips, ditches,
or small washes, coast in, using the engine as a
brake (transmission and transfer case lowest
gears). Then, use the low ranges in the
transmission and transfer case to power out.
258

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?
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