brakes HUMMER H3 2007 User Guide

StabiliTrak®System
Your vehicle has a vehicle stability enhancement
system called StabiliTrak®. It is an advanced
computer controlled system that assists you with
directional control of the vehicle in difficult
driving conditions.
StabiliTrak
®activates when the computer senses
a discrepancy between your intended path and
the direction the vehicle is actually traveling.
StabiliTrak
®selectively applies braking pressure at
any one of the vehicle’s brakes to assist the driver
with keeping the vehicle on the intended path.
When you rst start your vehicle and begin to drive
away, the system performs several diagnostic
checks to insure there are no problems. You may
hear or feel the system working. This is normal and
does not mean there is a problem with your vehicle.
If there is a problem detected with StabiliTrak
®,
a SERVICE STAB SYS message will be displayed
on the Driver Information Center (DIC). See
DIC Warnings and Messages on page 196for
more information. When this message is displayed,
the system is not operational. Adjust your driving
accordingly.StabiliTrak
®comes on automatically whenever you
start your vehicle. However, when the transfer
case is placed in Four-Wheel-Low Lock mode,
StabiliTrak
®is automatically disabled. See
Full-Time Four-Wheel Drive on page 111for more
information. To help assist you with directional
control of the vehicle, you should always leave the
system on. You can turn StabiliTrak
®off if you
ever need to using the TC (traction control) on/off
button. If you press and hold the TC button for
ve seconds, the StabiliTrak
®system and
the traction control system will turn off. When this
is done, the STAB SYS OFF message will be
displayed on the DIC. Press the TC button again
to turn StabiliTrak
®back on. SeeTraction
Control System (TCS) on page 241.
If your vehicle is in cruise control when the
StabiliTrak
®activates, the cruise control will
automatically disengage. When road conditions
allow you to safely use it again, you may reengage
the cruise control. See “Cruise Control on
page 159for more information.
244

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 238. 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.
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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.
Remember: Any traction control system helps avoid
only the acceleration skid. If your traction system is
off, then an acceleration skid is also best handled
by easing your foot off the accelerator pedal.
SeeTraction Control System (TCS) on page 241
andStabiliTrak
®System on page 244.
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.
Of course, traction is reduced when water,
snow, ice, gravel, or other material is on the
road. For safety, you will want to slow down
and adjust your driving to these conditions.
It is important to slow down on slippery surfaces
because stopping distance will be longer and
vehicle control more limited.
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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.
255

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

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.
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.
265

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. If you have an automatic transmission,
shift to PARK (P). 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.
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.
266

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 273
for more information on driving through water.
270

The heavier the rain, the harder it is to see.
Even if your windshield wiper blades are in good
shape, a heavy rain can make it harder to see
road signs and traffic signals, pavement markings,
the edge of the road, and even people walking.
It is wise to keep your wiping equipment in
good shape and keep your windshield washer uid
reservoir lled with washer uid. Replace your
windshield wiper inserts when they show signs
of streaking or missing areas on the windshield,
or when strips of rubber start to separate from
the inserts.
{CAUTION:
Wet brakes can cause accidents. They
may not work as well in a quick stop and
may cause pulling to one side. You could
lose control of the vehicle.
After driving through a large puddle of
water or a car wash, apply your brake pedal
lightly until your brakes work normally.Driving too fast through large water puddles or
even going through some car washes can cause
problems, too. The water may affect your brakes.
Try to avoid puddles. But if you cannot, try to slow
down before you hit them.
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.
274

If you drive regularly in steep country, or if you are
planning to visit there, here are some tips that
can make your trips safer and more enjoyable.
SeeOff-Road Driving on page 250for information
about driving off-road.
Keep your vehicle in good shape. Check all
uid levels and also the brakes, tires, cooling
system, and transmission. These parts can
work hard on mountain roads.
{CAUTION:
If you do not shift down, your brakes
could get so hot that they would not work
well. You would then have poor braking or
even none going down a hill. You could
crash. Shift down to let your engine assist
your brakes on a steep downhill slope.
{CAUTION:
Coasting downhill in NEUTRAL (N) or with
the ignition off is dangerous. Your brakes
will have to do all the work of slowing
down. They could get so hot that they
would not work well. You would then have
poor braking or even none going down a
hill. You could crash. Always have your
engine running and your vehicle in gear
when you go downhill.
Know how to go down hills. The most important
thing to know is this: let your engine do some of
the slowing down. Shift to a lower gear when
you go down a steep or long hill.
Know how to go uphill. You may want to shift
down to a lower gear. The lower gears help
cool your engine and transmission, and you can
climb the hill better.
280