2004 HUMMER H2 transmission

Brake and Throttle 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
overspeed the engine.
2. Select the proper transmission and transfer case
gear range; usually FIRST (1) gear, 4LO LOCK for
such obstacles.
3. If wheel spin is experienced, maintain steady
throttle, with your foot off the brake pedal, to
allow the TCS to control the wheel spin. TCS will
not operate if the brakes are applied, even slightly.
4. If wheel spin can not 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 such that a new
approach can be tried.
6. As the rst wheel crosses the obstacle, be prepared
to modulate the brake and throttle to maintain
control and avoid tire drop-off from obstacles.
Repeat the controlled process for the other wheels.For mounds, washouts, loose up-hill slopes,
ditches, etc.
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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 occuring on this
terrain. The operator should:
1. Reduce throttle, brake wheels.
2. Assess the terrain properly and adjust vehicle
speed and gear ranges accordingly: 4HI position
for higher speeds and 4LO 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 modulate the brake and throttle
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 listenfor 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.
{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’re
driving on or off the road, you and your
passengers should wear safety belts.
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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). 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 Your Tires Over Large
Rocks.Do not straddle
large rocks; drive
over them, letting the tire
envelop 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.
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Log Crossing.Using the proper technique, the
HUMMER H2 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 FIRST (1) and the transfer
case in 4LO LOCK and “walk” the HUMMER H2 over,
one tire at a time. As with all obstacles, face your tires
perpendicular to the object for best traction and tire life. 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.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 can
not do. There are some hills that simply can not 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 can not 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.
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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 (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.
Driving Uphill
Once you decide you can safely drive up the hill, you
need to take some special steps.
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
your speed. Do not use more power than you
need, because you do not want your wheels to start
spinning or sliding.
Let the traction system work to control any wheel
slippage. TC2 is designed to allow moderate
wheel spin with some capability to dig in and power
up the hill.
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Q:What should I do if my vehicle stalls, or
is about to stall, and I can not make it up
the hill?
A:If this happens, there are some things you should
do, and there are some things you must not do.
First, here is what youshoulddo:
Push the brake pedal to stop the vehicle and
keep it from rolling backwards. Also, apply the
parking brake.
If your engine is still running, shift the transmission
to REVERSE (R), release the parking brake, and
slowly back down the hill in REVERSE (R).
If your engine has stopped running, you will need to
restart it. With the brake pedal pressed and the
parking brake still applied, shift the transmission to
PARK (P) and 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 can
not make it up the hill, you must back straight
down the hill.
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Q:Suppose, after stalling, I try to back down the
hill and decide I just can not do it. What should
I do?
A:Set the parking brake, put your transmission in
PARK (P) and 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 PARK (P). 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 PARK (P). But do not shift
the transfer case to NEUTRAL. Leave the
transfer case in the 4 HI, 4 HI Lock or 4 LO
Lock position.
Driving Downhill
When off-roading takes you downhill, you will want to
consider a number of things:
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, then try to
keep your vehicle headed straight down, and use a
low gear. This way, engine drag can help your brakes
and they will not have to do all the work. Descend
slowly, keeping your 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.
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Q:Are there some things I should not do when
driving down a hill?
A:Yes! These are important because if you ignore
them you could lose control and have a serious
accident.
When driving downhill, avoid turns that take you
across the incline of the hill. A hill that is not too
steep to drive down may be too steep to drive
across. You could roll over if you do not drive
straight down.
Never go downhill with the transmission in
NEUTRAL (N). This is called “free-wheeling.”
Your brakes will have to do all the work and could
overheat and fade.
Q:Am I likely to stall when going downhill?
A:It is much more likely to happen going uphill. But if
it happens going downhill, here is what to do.
Stop your vehicle by applying the regular brakes.
Apply the parking brake.
Shift to PARK (P) and, while still braking, restart the
engine.
Shift back to a low gear, release the parking brake,
and drive straight down.
If the engine will not start, get out and get help.
Driving Across an Incline
Sooner or later, an off-road trail will probably go across
the incline of a hill. If this happens, you have to
decide whether to try to drive across the incline. Here
are some things to consider:
A hill that can be driven straight up or down may be
too steep to drive across. When you go straight up
or down a hill, the length of the wheel base (the
distance from the front wheels to the rear wheels)
reduces the likelihood the vehicle will tumble
end over end. But when you drive across an incline,
the much more narrow track width (the distance
between the left and right wheels) may not prevent
the vehicle from tilting and rolling over. Also,
driving across an incline puts more weight on the
downhill wheels. This could cause a downhill
slide or a rollover.
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