2009 HUMMER H3 Owners Manual

Scanning the Terrain
Off-road driving can take you over
many different kinds of terrain.
Be familiar with the terrain and its
many different features.
Surface Conditions:Off-roading
surfaces can be hard-packed
dirt, gravel, rocks, grass, sand,
mud, snow, or ice. Each of these
surfaces affects the vehicle’s
steering, acceleration, and braking
in different ways. Depending on
the surface, slipping, sliding, wheel
spinning, delayed acceleration,
poor traction, and longer braking
distances can occur.
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.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?
Will you have to stop suddenly or
change direction quickly?
When driving 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.
When driving over bumps, rocks, or
other obstacles, the 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.Off-roading requires a different
kind of alertness from driving on
paved roads and highways. There
are no road signs, posted speed
limits, or signal lights. Use
good judgment about what is safe
and what is not.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° minimum
approach (A), 75° maximum
approach angle (B).
Driving Your Vehicle 4-19

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.
Roll The 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, the
vehicle will cross logs up to
10 inches (25.4 cm) in diameter.
Approach the log at approximately a
15° angle (A) with the transmission
in 1 (First) and the transfer case
in Four-Wheel-Low Lock and “walk”
the vehicle over, one tire at a
time. It may be necessary to
modulate the brake pedal and
accelerator to avoid spin-out. Ease
the vehicle down from the log
with the brake.Driving on 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 the 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.
4-20 Driving Your Vehicle

Approaching a Hill
When you approach a hill, decide
if it is 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 might not see this
because the crest of the hill
is hidden by bushes, grass, or
shrubs.
Consider this 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?
What is beyond the hill? Is there
a cliff, an embankment, a
drop-off, a fence? Get out and
walk the hill if you do not know. It
is the smart way to nd out.
Is the hill simply too rough?
Steep hills often have ruts,
gullies, troughs, and exposed
rocks because they are
more susceptible to the effects
of erosion.
See “Hill Start Assist” underBraking
on page 4-3for information on
vehicles stopped on a grade.
Driving Uphill
Once you decide it is safe to drive
up the hill:
Use transmission and transfer
case low gear and get a rm
grip on the steering wheel.
Get a smooth start up the hill
and try to maintain speed.
Not using more power than
needed can avoid spinning the
wheels or sliding.
Let the traction system work to
control any wheel slippage.
The traction control system
allows for moderate wheel spin
with some capability to dig in and
power up the hill.
Driving Your Vehicle 4-21

Do not continue if the vehicle
shudders or exhibits suspension
hopping. This can cause
damage to the driveline or
suspension components.
Improper driving technique is not
covered by the vehicle warranty.
{CAUTION
Turning or driving across steep
hills can be dangerous. You could
lose traction, slide sideways, and
possibly roll over. You could be
seriously injured or killed. When
driving up hills, always try to go
straight up.
Try to drive straight up the hill if
at all possible. If the path twists
and turns, you might want to
nd another route.
Ease up on the speed as you
approach the top of the hill.
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, apply the parking
brake. If the vehicle has an
automatic transmission, shift the
transmission to P (Park).
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).
4-22 Driving Your Vehicle

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.
Things not to do if the vehicle stalls,
or is about to stall, when going
up a hill:
Never attempt to prevent a stall
by shifting into N (Neutral) to
rev-up the engine and regain
forward momentum. This will
not work. The vehicle can
roll backward very quickly and
could go out of control.
Never try to turn around if about
to stall when going up a hill. If
the hill is steep enough to
stall the vehicle, it is steep
enough to cause it to roll over. If
you cannot make it up the hill,
back straight down the hill.
If, after stalling, you try to back
down the hill and decide you just
cannot do it, set the parking brake.
If the vehicle has an automatic
transmission, shift to P (Park). Turn
off the engine. Leave the vehicle
and go get some help. Exit on
the uphill side and stay clear of the
path the vehicle would take if it
rolled downhill. Do not shift
the transfer case to Neutral when
you leave the vehicle. Leave it
in some gear.{CAUTION
Shifting the transfer case to
Neutral can cause your vehicle to
roll even if the transmission is in
P (Park). This is because the
Neutral position on the transfer
case overrides the transmission.
You or someone else could be
injured. If you are going to leave
your vehicle, set the parking
brake and shift the transmission
to P (Park). But do not shift the
transfer case to Neutral.
Driving Your Vehicle 4-23

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 Across an Incline
An off-road trail will probably go
across the incline of a hill. To decide
whether to try to drive across the
incline, consider the following:
{CAUTION
Driving across an incline that is
too steep will make your vehicle
roll over. You could be seriously
injured or killed. If you have any
doubt about the steepness of the
incline, do not drive across it. Find
another route instead.
A hill that can be driven
straight up or down might be
too steep to drive across. When
going straight up or down a
hill, the length of the wheel
base — the distance from
the front wheels to the rear
wheels —reduces the likelihoodthe vehicle will tumble end over
end. But when driving across
an incline, the narrower
track width — the distance
between the left and right
wheels — might not prevent the
vehicle from tilting and rolling
over. Driving across an incline
puts more weight on the downhill
wheels which could cause a
downhill slide or a rollover.
Surface conditions can be a
problem. Loose gravel, muddy
spots, or even wet grass can
cause the tires to slip sideways,
downhill. If the vehicle slips
sideways, it can hit something
that will trip it — a rock, a rut,
etc. — and roll over.
Hidden obstacles can make the
steepness of the incline even
worse. If you drive across a rock
with the uphill wheels, or if the
downhill wheels drop into a rut or
depression, the vehicle can tilt
even more.
For these reasons, carefully
consider whether to try to drive
across an incline. Just because the
trail goes across the incline does
not mean you have to drive it.
The last vehicle to try it might have
rolled over.
If you feel the vehicle starting to
slide sideways, turn downhill. This
should help straighten out the
vehicle and prevent the side
slipping. The best way to prevent
this is to “walk the course” rst,
so you know what the surface is like
before driving it.
Driving Your Vehicle 4-25

Stalling on an Incline
{CAUTION
Getting out on the downhill (low)
side of a vehicle stopped across
an incline is dangerous. If the
vehicle rolls over, you could be
crushed or killed. Always get out
on the uphill (high) side of the
vehicle and stay well clear of the
rollover path.
If the vehicle stalls when crossing
an incline, be sure you, and
any passengers, get out on the
uphill side, even if the door there is
harder to open. If you get out on
the downhill side and the vehicle
starts to roll over, you will be right in
its path.
If you have to walk down the slope,
stay out of the path the vehicle
will take if it does roll over.
Driving in Mud, Sand, Snow,
or Ice
When you drive in mud, snow, or
sand, the wheels do not get good
traction. Acceleration is not as quick,
turning is more difficult, and braking
distances are longer.
It is best to use a low gear when in
mud — the deeper the mud, the
lower the gear. In really deep mud,
keep the vehicle moving so it
does not get stuck.
When driving on sand, wheel
traction changes. On loosely packed
sand, such as on beaches or
sand dunes, the tires will tend to
sink into the sand. This affects
steering, accelerating, and braking.
Drive at a reduced speed and
avoid sharp turns or abrupt
maneuvers.Hard packed snow and ice offer the
worst tire traction. On these surfaces,
it is very easy to lose control. On wet
ice, for example, the traction is so
poor that you will have difficulty
accelerating. And, if the vehicle does
get moving, poor steering and
difficult braking can cause it to slide
out of control.
{CAUTION
Driving on frozen lakes, ponds, or
rivers can be dangerous.
Underwater springs, currents
under the ice, or sudden thaws
can weaken the ice. Your vehicle
could fall through the ice and you
and your passengers could
drown. Drive your vehicle on safe
surfaces only.
4-26 Driving Your Vehicle