wheel HUMMER H2 2007 Service Manual

Another feature of this system is the Traction
Control 2 (TC2) mode. TC2 should be selected for
improved traction and system performance
when the vehicle is on loose surfaces such as
deep sand or mud.
To enter this mode,
press the TC2 button
located on the
instrument panel to the
right of the steering
wheel.
TC2 only operates in the following transfer case
modes:
Four-Wheel-High Lock
Four-Wheel-Low Lock
Four-Wheel-Low Lock and Rear Axle Lock
SeeLocking Rear Axle on page 311for more
information on the rear axle lock.It will not operate in Four-Wheel-High. If the
TC2 button is pressed while in Four-Wheel High,
the light will ash for about 15 seconds and
then go out. The light should also come on briey
when you turn the ignition key to RUN; if it
doesn’t see your dealer for service.
If you restart your engine, the system reverts to
the standard TCS mode.
The traction off light will
come on when a
Traction Control System
or Anti-Lock Brake
System problem has
been detected and the
vehicle needs service.
SeeTraction Off Light on page 212.
When the traction off light is on, adjust your
driving accordingly.
The traction control system, as delivered from the
factory, will automatically come on whenever
you start your vehicle.
Adding non-GM accessories can affect your
vehicle’s performance. SeeAccessories and
Modications on page 392for more information.
310

Locking Rear Axle
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 above the
transfer case buttons
to the right of the
steering wheel.
To lock the rear axle, do the following:
1. Place the transfer case in the Four-Wheel-Low
Lock mode. This is the only mode which will
allow the rear axle to lock. SeeFull-Time
Four-Wheel Drive on page 128for more
information regarding the transfer case and
Four-Wheel-Low-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
vehicle’s 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 Four-Wheel-Low-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.
311

Steering
Power Steering
If you lose power steering assist because the
engine stops or the system is not functioning,
you can steer but it will take much more effort.
Steering Tips
It is important to take curves at a reasonable speed.
A lot of the “driver lost control” accidents
mentioned on the news happen on curves.
Here is why:
Experienced driver or beginner, each of us is
subject to the same laws of physics when driving on
curves. The traction of the tires against the road
surface makes it possible for the vehicle to change
its path when you turn the front wheels. If there is
no traction, inertia will keep the vehicle going in the
same direction. If you have ever tried to steer a
vehicle on wet ice, you will understand this.
The traction you can get in a curve depends on
the condition of your tires and the road surface,
the angle at which the curve is banked, and your
speed. While you are in a curve, speed is the
one factor you can control.Suppose you are steering through a sharp curve.
Then you suddenly accelerate. Both control
systems — steering and acceleration — have to
do their work where the tires meet the road.
Adding the sudden acceleration can demand too
much of those places. You can lose control.
SeeTraction Control System (TCS) on page 309.
What should you do if this ever happens? Ease
up on the accelerator pedal, steer the vehicle the
way you want it to go, and slow down.
Speed limit signs near curves warn that you
should adjust your speed. Of course, the posted
speeds are based on good weather and road
conditions. Under less favorable conditions you will
want to go slower.
If you need to reduce your speed as you approach
a curve, do it before you enter the curve, while
your front wheels are straight ahead.
Try to adjust your speed so you can “drive”
through the curve. Maintain a reasonable, steady
speed. Wait to accelerate until you are out of
the curve, and then accelerate gently into
the straightaway.
Adding non-GM accessories can affect your
vehicle’s performance. SeeAccessories and
Modications on page 392.
312

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 306. 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.
313

Off-Road Recovery
You may nd that your right wheels have dropped
off the edge of a road onto the shoulder while
you are driving.
If the level of the shoulder is only slightly below the
pavement, recovery should be fairly easy. Ease off
the accelerator and then, if there is nothing in the
way, steer so that your vehicle straddles the edge
of the pavement. You can turn the steering wheel
up to one-quarter turn until the right front tire
contacts the pavement edge. Then turn your
steering wheel to go straight down the roadway.
Passing
The driver of a vehicle about to pass another on a
two-lane highway waits for just the right moment,
accelerates, moves around the vehicle ahead, then
goes back into the right lane again. A simple
maneuver?
Not necessarily! Passing another vehicle on a
two-lane highway is a potentially dangerous
move, since the passing vehicle occupies the
same lane as oncoming traffic for several seconds.
A miscalculation, an error in judgment, or a brief
surrender to frustration or anger can suddenly put
the passing driver face to face with the worst of all
traffic accidents — the head-on collision.
So here are some tips for passing:
Drive ahead. Look down the road, to the sides,
and to crossroads for situations that might
affect your passing patterns. If you have any
doubt whatsoever about making a successful
pass, wait for a better time.
314

Loss of Control
Let us review what driving experts say about what
happens when the three control systems — brakes,
steering, and acceleration — do not have enough
friction where the tires meet the road to do what the
driver has asked.
In any emergency, do not give up. Keep trying to
steer and constantly seek an escape route or
area of less danger.
Skidding
In a skid, a driver can lose control of the vehicle.
Defensive drivers avoid most skids by taking
reasonable care suited to existing conditions, and
by not overdriving those conditions. But skids
are always possible.The three types of skids correspond to your
vehicle’s three control systems. In the braking skid,
your wheels are not rolling. In the steering or
cornering skid, too much speed or steering in a
curve causes tires to slip and lose cornering force.
And in the acceleration skid, too much throttle
causes the driving wheels to spin.
A cornering skid is best handled by easing your
foot off the accelerator pedal.
If your vehicle starts to slide, ease your foot off
the accelerator pedal and quickly steer the
way you want the vehicle to go. If you start
steering quickly enough, your vehicle may
straighten out. Always be ready for a second skid
if it occurs.
316

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. Remove any removable side steps.
SeeAssist Steps on page 338. 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.
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.
318

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 362
andTires on page 448.
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.
319

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.
323

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.
324