2005 GMC YUKON traction control

The StabiliTrak®button is
located on the instrument
panel.
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.
Four-wheel-drive vehicles must be in 2HI, 4HI
or AUTO 4WD 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 Your Vehicle is Stuck in
Sand, Mud, Ice or Snow on page 4-49.
When the transfer case is in 4LO, the stability system is
automatically disabled, and the STABILITY SYS
DISABLED message will appear on the DIC. In 4LO,
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.
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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, see
Driver Information Center (DIC) on page 3-54.
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 the
transfer case. This could lead to costly repairs not
covered by your warranty.
If the brake traction-control system activates constantly
or if the brakes have heated up due to high speed
braking, brake traction-control will be disabled and the
TRACTION SYS LIMITED message will be displayed. In
the limited mode, the traction-control system will only
use engine traction-control and is limited in it’s ability to
provide optimal performance since the system will
not utilize brake traction-control to control slip on the
drive wheels. The system will return to normal operation
after the brakes have cooled. This can take up to two
minutes or longer depending on brake usage.Notice:If you allow the wheel(s) of one axle to spin
excessively while the traction off, ABS and brake
warning lights and the SERVICE STABILITY
message are displayed, you could damage the
transfer case. The repairs would not be covered by
your warranty. Reduce engine power and do not
spin the wheel(s) excessively while these lights and
this message are 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 (DIC), and the
cruise control will automatically disengage. When road
conditions allow you to use cruise again, you may
re-engage the cruise control. SeeCruise Control on
page 3-11.
StabiliTrak
®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.
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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 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 Assist System (TAS) on
page 4-8.
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.
4-13

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 you have the Traction Assist System (TAS),
remember: It helps avoid only the acceleration skid. See
Traction Assist System (TAS) on page 4-8. If you do
not have this system, or if the system is off, then
an acceleration skid is also 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.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.
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.
4-20

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.
Surface Obstacles:Unseen or hidden obstacles can
be hazardous. A rock, log, hole, rut or bump can startle
you if you are not prepared for them. Often these
obstacles are hidden by grass, bushes, snow or even
the rise and fall of the terrain itself. Here are some
things to consider:
Is the path ahead clear?
Will the surface texture change abruptly up ahead?
Does the travel take you uphill or downhill?
There is more discussion of these subjects later.
Will you have to stop suddenly or change direction
quickly?
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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.
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.
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.
4-34

Uniform Tire Quality Grading
Quality grades can be found where applicable on the
tire sidewall between tread shoulder and maximum
section width. For example:
Treadwear 200 Traction AA Temperature A
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration, which grades tires by
treadwear, traction and temperature performance.
(This applies only to vehicles sold in the United States.)
The grades are molded on the sidewalls of most
passenger car tires. The Uniform Tire Quality Grading
system does not apply to deep tread, winter-type
snow tires, space-saver or temporary use spare tires,
tires with nominal rim diameters of 10 to 12 inches
(25 to 30 cm), or to some limited-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specied government test course.
For example, a tire graded 150 would wear one and
a half (1.5) times as well on the government course as
a tire graded 100. The relative performance of tires
depends upon the actual conditions of their use,
however, and may depart signicantly from the norm
due to variations in driving habits, service practices and
differences in road characteristics and climate.
Traction – AA, A, B, C
The traction grades, from highest to lowest, are AA, A,
B, and C. Those grades represent the tire’s ability
to stop on wet pavement as measured under controlled
conditions on specied government test surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance. Warning: The traction grade
assigned to this tire is based on straight-ahead braking
traction tests, and does not include acceleration,
cornering, hydroplaning, or peak traction characteristics.
5-72

Tire Chains
{CAUTION:
If your vehicle has P265/75R16, LT265/75R16,
P265/70R16 or P265/70R17 size tires, don’t use
tire chains. They can damage your vehicle
because there’s not enough clearance. Tire
chains used on a vehicle without the proper
amount of clearance can cause damage to the
brakes, suspension or other vehicle parts. The
area damaged by the tire chains could cause
you to lose control of your vehicle and you or
others may be injured in a crash.
Use another type of traction device only if its
manufacturer recommends it for use on your
vehicle and tire size combination and road
conditions. Follow that manufacturer’s
instructions. To help avoid damage to your
vehicle, drive slowly, readjust or remove the
device if it’s contacting your vehicle, and don’t
spin your wheels.
If you do nd traction devices that will t,
install them on the rear tires.Notice:If you have a tire size other than P265/75R16,
LT265/75R16, P265/70R16 or P265/70R17 use tire
chains only where legal and only when you must. Use
chains that are the proper size for your tires. Install
them on the rear tires only.
Don’t use chains on the front tires.
Tighten them as tightly as possible with the ends
securely fastened. Drive slowly and follow the chain
manufacturer’s instructions. If you can hear the
chains contacting your vehicle, stop and retighten
them. If the contact continues, slow down until
it stops. Driving too fast or spinning the wheels with
chains on will damage your vehicle.
5-75