engine GMC YUKON 2003 Workshop Manual

Stabilitrak®and part of the traction control system can
be turned off or back on by pressing the
Stabilitrak
®button. All-wheel drive vehicles must be in
all-wheel drive mode to turn the system on or off.
When the system is turned off, the traction off light will
illuminate, and the STABILITY SYS DISABLED
message will appear on the DIC to warn the driver that
both the stability system and part of the traction
control system are disabled. Your vehicle will still have
brake-traction control when Stabilitrak
®is off, but
will not be able to use the engine speed management
system. See“Traction Control Operation”next for
more information.
When the Stabilitrak
®system has been turned off you
may still hear system noises as a result of the
brake-traction control coming on.
It is recommended to leave the system on for normal
driving conditions, but it may be necessary to turn
the system off if your vehicle is stuck in sand, mud, ice
or snow, and you want to“rock”your vehicle to
attempt to free it. It may also be necessary to turn off
the system when driving in extreme off-road conditions
where high wheel spin is required. SeeIf You Are
Stuck: In Sand, Mud, Ice or Snow on page 4-52.
When the transfer case is in 4 low, the stability system
is automatically disabled, and the STABILITY SYS
DISABLED message will appear on the DIC. In 4 low,
the Stabilitrak
®button only turns the traction control
system on and off.
Traction Control Operation
The traction control system is part of the
Stabilitrak®system. Traction control limits wheel spin by
reducing engine power to the wheels (engine speed
management) and by applying brakes to each individual
wheel (brake-traction control) as necessary.
The traction control system is enabled automatically
when you start your vehicle, and it will activate and
display the TRACTION ACTIVE message in the Driver
Information Center (DIC) if it senses that any of the
wheels are spinning or beginning to lose traction while
driving. If you turn off Stabilitrak
®, only the brake-traction
control portion of traction control will work. The engine
speed management will be disabled. In this state, engine
power is not reduced automatically and the driven wheels
can spin more freely. This can cause the brake-traction
control to activate constantly. For more information on the
traction active message, seeDriver Information Center
(DIC) on page 3-53.
Notice:If the traction off light comes on due to
heavy braking and/or because the traction control
system has been continuously active, do not
allow the wheel(s) of one axle to spin excessively.If
you do, you may be causing damage to your
transfer case.This could lead to costly repairs not
covered by your warranty.
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If the brake-traction control system activates constantly
or if the brakes have heated up due to high speed
braking, the brake-traction control will be automatically
disabled. The system will come back on after the
brakes have cooled. This can take up to two minutes or
longer depending on brake usage.
Notice:Don’t allow the wheel(s) of one axle to spin
excessively when the traction off, ABS and brake
lights are on and the SERVICE STABILITY MESSAGE
is displayed. In this situation, damage to the
transfer case is possible. This could lead to costly
repairs not covered by your warranty. You should
immediately reduce engine power until the lights
and messages are no longer displayed.
The traction control system may activate on dry or
rough roads or under conditions such as heavy
acceleration while turning or abrupt upshifts/downshifts
of the transmission. When this happens you may
notice a reduction in acceleration, or may hear a noise
or vibration. This is normal.
If your vehicle is in cruise control when the system
activates, the STABILITY SYS ACTIVE message will
appear on the Driver Information Center and the cruise
control will automatically disengage. When road
conditions allow you to use cruise again, you may
re-engage the cruise control. See“Cruise Control”under
Turn Signal/Multifunction Lever on page 3-8Stabilitrak®may also turn off automatically if it
determines that a problem exists with the system. If the
problem does not clear itself after restarting the
vehicle, you should see your dealer for service.
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
Driving on Curves
It’s important to take curves at a reasonable speed.
A lot of the“driver lost control”accidents mentioned on
the news happen on curves. Here’s 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’s no traction, inertia
will keep the vehicle going in the same direction. If
you’ve ever tried to steer a vehicle on wet ice, you’ll
understand this.
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Of course, traction is reduced when water, snow, ice,
gravel or other material is on the road. For safety, you’ll
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.
While driving on a surface with reduced traction, try
your best to avoid sudden steering, acceleration
or braking (including engine braking by shifting to a
lower gear). Any sudden changes could cause the tires
to slide. You may not realize the surface is slippery
until your vehicle is skidding. Learn to recognize warning
clues—such as enough water, ice or packed snow
on the road to make a“mirrored surface”—and slow
down when you have any doubt.
Remember: Any anti-lock brake system (ABS) helps
avoid only the braking skid.
Off-Road Driving with Your
Four-Wheel-Drive Vehicle
This off-road guide is for vehicles that have four-wheel
drive. Also, seeBraking on page 4-6. If your vehicle
doesn’t have four-wheel drive, you shouldn’t drive
off-road unless you’re on a level, solid surface.Off-road driving can be great fun. But it does have
some denite hazards. The greatest of these is
the terrain itself.
“Off-roading”means you’ve left the great North American
road system behind. Traffic lanes aren’t marked.
Curves aren’t banked. There are no road signs.
Surfaces can be slippery, rough, uphill or downhill. In
short, you’ve gone right back to nature.
Off-road driving involves some new skills. And that’s
why it’s very important that you read this guide.
You’llnd many driving tips and suggestions. These will
help make your off-road driving safer and more
enjoyable.
If you think you will need some more ground clearance
at the front of your vehicle, you can easily remove
the front bumper lower air dam.
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3. Pull the push-pins and
lower air dam assembly
away from the
retainers until the lower
air dam is free.
When you’re back on roads, though, be sure to replace
the air dam.
Notice:Operating your vehicle for extended
periods without the front bumper lower air dam
installed can cause improper air flow to the engine
and may allow things like fog lamps or tow hooks
on the front of your vehicle to be damaged. Always
be sure to replace the front bumper air dam when
you’re finished off-road driving.To reinstall the lower air dam do the following:
1. Line up each push-pin
with its intended
retainer and push the
washer portion of
the push-pin towards
the retainer until it locks
into place.
2. Push theat end of the
push-pin towards the
retainer until it
locks into place,
making sure each is
secure.
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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 openres (where
permitted), camp stoves and lanterns.
Never park your vehicle over dry grass or other
combustible materials that could catchre from
the heat of the vehicle’s exhaust system.
Traveling to Remote Areas
It makes sense to plan your trip, especially when going
to a remote area. Know the terrain and plan your
route. You are much less likely to get bad surprises.
Get accurate maps of trails and terrain. Try to learn of
any blocked or closed roads.
It’s also a good idea to travel with at least one other
vehicle. If something happens to one of them, the other
can help quickly.
Does your vehicle have a winch? If so, be sure to read
the winch instructions. In a remote area, a winch
can be handy if you get stuck. But you’ll want to know
how to use it properly.
Getting Familiar with Off-Road Driving
It’s a good idea to practice in an area that’s safe
and close to home before you go into the wilderness.
Off-road driving does require some new and different
skills. Here’s 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’ll need to respond to
vibrations and vehicle bounce.
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Ease up on your speed as you approach the top of
the hill.
Attach aag to the vehicle to make you 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’re there.
Use your headlamps even during the day. They
make you 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.
Q:What should I do if my vehicle stalls, or is
about to stall, and I can’t 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’s 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’ll 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’ll be able to tell if your wheels
are straight and maneuver as you back down. It’s
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.
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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 won’t 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’s steep enough to
cause you to roll over if you turn around. If you can’t
make it up the hill, you must back straight down
the hill.
Q:Suppose, after stalling, I try to back down the
hill and decide I just can’t 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 2 Wheel High, 4 High or 4 Low
position.
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Driving Downhill
When off-roading takes you downhill, you’ll want to
consider a number of things:
How steep is the downhill? Will I be able to maintain
vehicle control?
What’s the surface like? Smooth? Rough? Slippery?
Hard-packed dirt? Gravel?
Are there hidden surface obstacles? Ruts? Logs?
Boulders?
What’s 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 won’t 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’s not too
steep to drive down may be too steep to drive
across. You could roll over if you don’t 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.
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Q:Am I likely to stall when going downhill?
A:It’s much more likely to happen going uphill. But if
it happens going downhill, here’s 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 won’t 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 (thedistance 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.
Surface conditions can be a problem when you drive
across a hill. Loose gravel, muddy spots, or even wet
grass can cause your 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, your vehicle can tilt even more.
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Driving in Water
Heavy rain can meanashooding, andood waters
demand extreme caution.
Find out how deep the water is before you drive through
it. If it’s deep enough to cover your wheel hubs, axles
or exhaust pipe, don’t try it—you probably won’t
get through. Also, water that deep can damage your
axle and other vehicle parts.
If the water isn’t 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’ll 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’s only shallow water, it can
still wash away the ground from under your
tires, and you could lose traction and roll the
vehicle over. Don’t drive through rushing
water.
SeeDriving in Rain and on Wet Roads on page 4-39for
more information on driving through water.
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