engine HUMMER H2 2006 Workshop Manual

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, 4LO 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.
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: 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 alternate between braking and
accelerating through the adverse terrain.
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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.
{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.
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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 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.
4-24

Q:What should I do if my vehicle stalls, or
is about to stall, and I cannot 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
cannot make it up the hill, you must back straight
down the hill.
4-28

Q:Suppose, after stalling, I try to back down the
hill and decide I just cannot 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.
4-29

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:
1. Stop your vehicle by applying the regular brakes.
Apply the parking brake.
2. Shift to PARK (P) and, 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.
4-30

Stalling on an Incline
If your vehicle stalls when you are 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.{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.
Driving in Mud, Sand, Snow, or Ice
When you drive in mud, snow, or sand, your wheels will
not get good traction. You cannot accelerate as quickly,
turning is more difficult, and you will need longer braking
distances.
It is best to use a low gear when you are in mud — the
deeper the mud, the lower the gear. In really deep
mud, the idea is to keep your vehicle moving so you do
not get stuck. Be careful to keep mud from building
up and washing onto the engine cooling system.
When you drive on sand, you will sense a change in
wheel traction. But it will depend upon how loosely
packed the sand is. On loosely packed sand, such as
on beaches or sand dunes, your tires will tend to
sink into the sand. This has an effect on steering,
accelerating, and braking. Drive at a reduced speed and
avoid sharp turns or abrupt maneuvers.
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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 you do get
moving, poor steering and difficult braking can cause
you 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.
Driving in Water
Heavy rain can mean ash ooding, and ood waters
demand extreme caution.
Find out how deep the water is before you drive through
it. If it is deep enough to cover your wheel hubs, axles, or
exhaust pipe, do not try it — you probably will not get
through. Also, water that deep can damage your axle and
other vehicle parts. Your vehicle is capable of depths up
to 20 inches. 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 your ignition
system and your vehicle can stall. Stalling can also
occur if you get your tailpipe under water. And, as long
as your tailpipe is under water, you will never be
able to start your engine. When you go through water,
remember that when your brakes get wet, it may
take you longer to stop.
{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.
SeeDriving in Rain and on Wet Roads on page 4-39for
more information on driving through water.
4-33

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. Also, check the
fuel lines and cooling system for any leakage.
Your vehicle will require more frequent service due to
off-road use. See the Maintenance Schedule for
additional information.
Assist Steps
Your vehicle may be equipped with removable side steps.
Remove the steps prior to off-roading to give your
vehicle more ground clearance and to prevent damage
to the vehicle from the side steps dragging and/or
catching on obstacles.
Notice:Do not drive off-road with the side steps
attached to your vehicle. You can damage the side
steps and/or your vehicle’s frame if they get caught
or drag against an obstacle. This damage would not
be covered by your vehicle’s warranty. Always
remove the side steps prior to any off-road driving.
U-Type Side Steps
The following instructions show how to install the
optional U-type steps. If you want to remove them, just
reverse the instructions:
1. Start with the side step brackets pointing up and
away from you, or just make sure the HUMMER
logo faces up.
2. For the front step, use the rst and third brackets
on the vehicle from the front tire. For the rear step,
use the rst and third brackets on the vehicle
from the rear tire.
You will notice that the side steps have pins on
both sides of the step brackets. This is because the
steps are interchangeable between front/back
and the driver/passenger sides of the vehicle. Use
the pins as follows:
Driver Side:Look at the side step with the
HUMMER logo facing you. You will use the pins
which are on the right side of each side step
bracket. This works for the front or rear of
the vehicle.
Passenger Side:Look at the side step with the
HUMMER logo facing you. You will use the pins
which are on the left side of each side step
bracket. This works for the front or rear of
the vehicle.
4-34

Hydroplaning
Hydroplaning is dangerous. So much water can build up
under your tires that they can 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.
Hydroplaning does not happen often. But it can if your
tires do not have much tread or if the pressure in
one or more is low. It can happen if a lot of water is
standing on the road. If you can see reections
from trees, telephone poles, or other vehicles, and
raindrops dimple the water’s surface, there could
be hydroplaning.
Hydroplaning usually happens at higher speeds. There
just is not a hard and fast rule about hydroplaning.
The best advice is to slow down when it is raining.
Driving Through Deep Standing Water
Notice:If you drive too quickly through deep
puddles or standing water, water can come in
through your engine’s air intake and badly damage
your engine. Never drive through water that is
slightly lower than the underbody of your vehicle. If
you cannot avoid deep puddles or standing water,
drive through them very slowly.
Driving Through Flowing Water
{CAUTION:
Flowing or rushing water creates strong forces.
If you try to drive through owing water, as you
might at a low water crossing, your vehicle can
be carried away. As little as six inches of
owing water can carry away a smaller vehicle.
If this happens, you and other vehicle
occupants could drown. Do not ignore police
warning signs, and otherwise be very cautious
about trying to drive through owing water.
Some Other Rainy Weather Tips
Besides slowing down, allow some extra following
distance. And be especially careful when you
pass another vehicle. Allow yourself more clear
room ahead, and be prepared to have your
view restricted by road spray.
Have good tires with proper tread depth. SeeTires
on page 5-53.
4-40