engine GMC YUKON 2008 Repair Manual

TRANSMISSION HOT IDLE ENGINE
Notice:If you drive your vehicle while the
transmission uid is overheating and the
transmission temperature warning is displayed on
the instrument panel cluster and/or DIC, you
can damage the transmission. This could lead to
costly repairs that would not be covered by
your warranty. Do not drive your vehicle with
overheated transmission uid or while the
transmission temperature warning is displayed.
This message displays along with a continuous chime if
the transmission uid in the vehicle gets hot. Driving
with the transmission uid temperature high can cause
damage to the vehicle. Stop the vehicle and let it
idle to allow the transmission to cool. This message
clears and the chime stops when the uid temperature
reaches a safe level.
TURN SIGNAL ON
This message displays and a chime sounds if a turn
signal is left on for 3/4 of a mile (1.2 km). Move the turn
signal/multifunction lever to the off position.
WASHER FLUID LOW ADD FLUID
This message displays when the windshield washer
uid is low. Fill the windshield washer uid reservoir as
soon as possible. SeeEngine Compartment Overview
on page 5-14for the location of the windshield
washer uid reservoir. Also, seeWindshield Washer
Fluid on page 5-40for more information.
DIC Vehicle Customization
(With DIC Buttons)
Your vehicle may have customization capabilities that
allow you to program certain features to one preferred
setting. Customization features can only be programmed
to one setting on the vehicle and cannot be programmed
to a preferred setting for two different drivers.
All of the customization options may not be available on
your vehicle. Only the options available will be
displayed on the DIC.
The default settings for the customization features were
set when your vehicle left the factory, but may have
been changed from their default state since then.
The customization preferences are automatically
recalled.
To change customization preferences, use the following
procedure.
3-72

REMOTE START
If your vehicle has this feature, it allows you to turn the
remote start off or on. The remote start feature allows
you to start the engine from outside of the vehicle using
the Remote Keyless Entry (RKE) transmitter. See
Remote Vehicle Start on page 2-8for more information.
Press the customization button until REMOTE START
appears on the DIC display. Press the set/reset
button once to access the settings for this feature. Then
press the customization button to scroll through the
following settings:
OFF:The remote start feature will be disabled.
ON (default):The remote start feature will be enabled.
NO CHANGE:No change will be made to this
feature. The current setting will remain.
To select a setting, press the set/reset button while the
desired setting is displayed on the DIC.
FACTORY SETTINGS
This feature allows you to set all of the customization
features back to their factory default settings.
Press the customization button until FACTORY
SETTINGS appears on the DIC display. Press the
set/reset button once to access the settings for
this feature. Then press the customization button to
scroll through the following settings:
RESTORE ALL (default):The customization features
will be set to their factory default settings.
DO NOT RESTORE:The customization features will
not be set to their factory default settings.
To select a setting, press the set/reset button while the
desired setting is displayed on the DIC.
3-80

While your vehicle is parked:
Familiarize yourself with all of its controls.
Familiarize yourself with its operation.
Set up your audio system by presetting your
favorite radio stations, setting the tone, and
adjusting the speakers. Then, when driving
conditions permit, you can tune to your favorite
radio stations using the presets and steering wheel
controls if the vehicle has them.
Notice:Before adding any sound equipment to
your vehicle, such as an audio system, CD player,
CB radio, mobile telephone, or two-way radio, make
sure that it can be added by checking with your
dealer/retailer. Also, check federal rules covering
mobile radio and telephone units. If sound
equipment can be added, it is very important to do
it properly. Added sound equipment may interfere
with the operation of your vehicle’s engine, radio, or
other systems, and even damage them. Your
vehicle’s systems may interfere with the operation
of sound equipment that has been added.
Your vehicle has a feature called Retained Accessory
Power (RAP). With RAP, the audio system can be
played even after the ignition is turned off. SeeRetained
Accessory Power (RAP) on page 2-27for more
information.
Setting the Clock
MP3 Radios with a Single CD or a
Single CD and DVD Player
If your vehicle has a radio with a single CD or a CD and
DVD player, it has a
H(clock) button for setting the
time and date.
To set the time and date, follow the instructions:
1. Press the
Hbutton and the HR, MIN, MM, DD,
YYYY (hour, minute, month, day, and year)
displays.
2. Press the pushbutton located under any one of the
labels that you want to change. Every time the
pushbutton is pressed again, the time or the date if
selected, increases by one.
Another way to increase the time or date, is to
press the right
¨SEEK arrow or the\
FWD (forward) button.
To decrease the time or date, press the left©
SEEK arrow or thesREV (reverse) button.
You can also turn the
f(tune) knob, located on
the upper right side of the radio, to adjust the
selected setting.
3-82

Braking
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
SeeBrake System Warning Light on page 3-44.
Braking action involves perception time and reaction
time. First, you have to decide to push on the brake
pedal. That is perception time. Then you have to bring up
your foot and do it. That is reaction time.
Average reaction time is about three-fourths of a second.
But that is only an average. It might be less with one
driver and as long as two or three seconds or more with
another. Age, physical condition, alertness, coordination,
and eyesight all play a part. So do alcohol, drugs, and
frustration. But even in three-fourths of a second, a
vehicle moving at 60 mph (100 km/h) travels 66 feet
(20 m). That could be a lot of distance in an emergency,
so keeping enough space between your vehicle and
others is important.
And, of course, actual stopping distances vary greatly
with the surface of the road, whether it is pavement
or gravel; the condition of the road, whether it is
wet, dry, or icy; tire tread; the condition of the brakes;
the weight of the vehicle; and the amount of brake force
applied.Avoid needless heavy braking. Some people drive in
spurts — heavy acceleration followed by heavy
braking — rather than keeping pace with traffic. This is
a mistake. The brakes might not have time to cool
between hard stops. The brakes will wear out much
faster if you do a lot of heavy braking. If you keep pace
with the traffic and allow realistic following distances,
you will eliminate a lot of unnecessary braking.
That means better braking and longer brake life.
If your vehicle’s engine ever stops while you are driving,
brake normally but do not pump the brakes. If you do,
the pedal could get harder to push down. If the
engine stops, you will still have some power brake
assist. But you will use it when you brake. Once the
power assist is used up, it can take longer to stop and
the brake pedal will be harder to push.
Adding non-dealer/non-retailer accessories can affect
your vehicle’s performance. SeeAccessories and
Modifications on page 5-3.
4-4

Antilock Brake System (ABS)
Your vehicle has the Antilock Brake System (ABS), an
advanced electronic braking system that will help
prevent a braking skid.
When you start the engine and begin to drive away,
ABS will check itself. You might hear a momentary
motor or clicking noise while this test is going on. This
is normal.
If there is a problem with
ABS, this warning light will
stay on. SeeAntilock
Brake System Warning
Light on page 3-46.
Along with ABS, your vehicle has a Dynamic Rear
Proportioning (DRP) system. If there is a DRP problem,
both the brake and ABS warning lights come on
accompanied by a 10-second chime. The lights and
chime will come on each time the ignition is turned on
until the problem is repaired. See your dealer/retailer for
service.Let us say the road is wet and you are driving safely.
Suddenly, an animal jumps out in front of you. You slam
on the brakes and continue braking. Here is what
happens with ABS:
A computer senses that wheels are slowing down. If
one of the wheels is about to stop rolling, the computer
will separately work the brakes at each front wheel
and at both rear wheels.
ABS can change the brake pressure faster than any
driver could. The computer is programmed to make the
most of available tire and road conditions. This can
help you steer around the obstacle while braking hard.
As you brake, the computer keeps receiving updates
on wheel speed and controls braking pressure
accordingly.
Remember: ABS does not change the time you need to
get your foot up to the brake pedal or always decrease
stopping distance. If you get too close to the vehicle in
front of you, you will not have time to apply the brakes if
that vehicle suddenly slows or stops. Always leave
enough room up ahead to stop, even though you
have ABS.
4-5

The StabiliTrak®light will
ash on the instrument
panel cluster when
the system is both on and
activated.
You may also feel or hear the system working; this is
normal.
The traction control disable
button is located on the
instrument panel below the
climate controls.
The traction control part of StabiliTrak
®can be turned
off by pressing and releasing the StabiliTrak®button
if both systems (traction control and StabiliTrak®) were
previously on. To disable both traction control and
StabiliTrak
®, press and hold the button for ve seconds.
Traction control and StabiliTrak
®can be turned on by
pressing and releasing the StabiliTrak®button if
not automatically shut off for any other reason.When the TCS or StabiliTrak
®system is turned off, the
StabiliTrak®light and the appropriate TCS off or
StabiliTrak®off message will be displayed on the DIC to
warn the driver. Your vehicle will still have brake-traction
control when traction control is off, but will not be
able to use the engine speed management system. See
“Traction Control Operation” next for more information.
When the traction control 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 4-33.
When the transfer case is in 4LO, the stability system is
automatically disabled, the StabiliTrak
®light will come
on and the STABILITRAK OFF message will appear on
the DIC. Both traction control and StabiliTrak
®are
automatically disabled in this condition.
4-7

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. It will activate and the
StabiliTrak
®light will ash if it senses that any of the
wheels are spinning or beginning to lose traction while
driving. If you turn off traction control, only the
brake-traction control portion of traction control will
work. The engine speed management will be disabled.
In this mode, engine power is not reduced automatically
and the driven wheels can spin more freely. This can
cause the brake-traction control to activate constantly.
Notice:If you allow the wheel(s) of one axle to spin
excessively while the StabiliTrak
®, ABS and brake
warning lights and the SERVICE STABILITRAK
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 StabiliTrak
®light will ash 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 3-13.
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/retailer for service.
4-8

Steering
Power Steering
If your vehicle is a Two-mode Hybrid, see the Two-mode
Hybrid manual for more information.
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 the 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. SeeStabiliTrak
®System on
page 4-6.
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 the 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-dealer/non-retailer accessories can affect
your vehicle’s performance. SeeAccessories and
Modifications on page 5-3.
4-9

Off-Road Driving
This off-road guide is for vehicles that have four-wheel
drive. Also, seeBraking on page 4-4. If your vehicle
does not have four-wheel drive, you should not
drive off-road unless you are on a level, solid surface.
The airbag system is designed to work properly under a
wide range of conditions, including off-road usage.
Observe safe driving speeds, especially on rough
terrain. As always, wear your safety belt.
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 have left the great North
American road system behind. Traffic lanes are not
marked. Curves are not banked. There are no
road signs. Surfaces can be slippery, rough, uphill or
downhill. In short, you have gone right back to nature.
Off-road driving involves some new skills. And that
is why it is very important that you read this guide. You
will nd 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 remove the front
fascia lower air dam.The front fascia lower air dam is held in place by two
bolts and 10 snap features. The bolts and snap features
are accessible from underneath the front fascia.
The following steps must be performed on the bolts and
snap features to remove the air dam:
1. Remove the two outboard air dam bolts.
2. With a at-blade screwdriver, push down on the
snap features and disengage the snaps.
3. After the bolts are removed and the snaps are
disengaged, push forward on the air dam until it
is free.
When you are back on roads, though, be sure to
replace the air dam.
Notice:Operating your vehicle for extended
periods without the front fascia lower air dam
installed can cause improper air ow to the engine.
Always be sure to replace the front fascia air
dam when you are nished off-road driving.
To reinstall the lower air dam do the following:
1. Line up the snap features and push the air dam
rearward to engage the snaps.
2. Install the two outboard bolts.
4-13

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.
4-16