2002 GMC YUKON DENALI service

2-74
Did you just drive through a deep puddle of water?
If so, your electrical system may be wet. The condition
will usually be corrected when the electrical system
dries out. A few driving trips should turn the light off.
Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel. See
ªFuelº in the Index. Poor fuel quality will cause your
engine not to run as efficiently as designed. You may
notice this as stalling after start
-up, stalling when you
put the vehicle into gear, misfiring, hesitation on
acceleration or stumbling on acceleration. (These
conditions may go away once the engine is warmed up.)
This will be detected by the system and cause the light
to turn on.
If you experience one or more of these conditions,
change the fuel brand you use. It will require at least
one full tank of the proper fuel to turn the light off.
If none of the above steps have made the light turn off,
have your dealer or qualified service center check the
vehicle. Your dealer has the proper test equipment and
diagnostic tools to fix any mechanical or electrical
problems that may have developed.Emissions Inspection and Maintenance Programs
Some state/provincial and local governments have
or may begin programs to inspect the emission
control equipment on your vehicle. Failure to pass
this inspection could prevent you from getting a
vehicle registration.
Here are some things you need to know in order to
help your vehicle pass an inspection:
Your vehicle will not pass this inspection if the
SERVICE ENGINE SOON or CHECK ENGINE light
is on or not working properly.
Your vehicle will not pass this inspection if the OBD
(on
-board diagnostic) system determines that critical
emission control systems have not been completely
diagnosed by the system. The vehicle would be
considered not ready for inspection. This can happen
if you have recently replaced your battery or if your
battery has run down. The diagnostic system is designed
to evaluate critical emission control systems during
normal driving. This may take several days of routine
driving. If you have done this and your vehicle still
does not pass the inspection for lack of OBD system
readiness, see your dealer or qualified service center to
prepare the vehicle for inspection.

2-75 Oil Pressure Gage
United States Canada
The oil pressure gage shows the engine oil pressure in
psi (pounds per square inch) when the engine is running.
Canadian vehicles indicate pressure in kPa (kilopascals).
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but readings above the
low pressure zone indicate the normal operating range.
A reading in the low pressure zone may be caused by a
dangerously low oil level or some other problem
causing low oil pressure. Check your oil as soon as
possible. See ªCheck Eng Oil Pressureº and ªEngine
Oilº in the Index.
CAUTION:
Don't keep driving if the oil pressure is low.
If you do, your engine can become so hot that it
catches fire. You or others could be burned.
Check your oil as soon as possible and have your
vehicle serviced.
NOTICE:
Damage to your engine from neglected oil
problems can be costly and is not covered by
your warranty.

2-80 Low Coolant
This message is displayed
when the cooling system is
low on coolant.
The engine may overheat. See ªEngine Coolantº in
the Index and have your vehicle serviced as soon as
you can.
Check Coolant Temp
This message is displayed
when the cooling system
temperature gets hot.
Check the coolant temperature gage and the coolant
level. See ªEngine Coolant,º ªEngine Coolant
Temperature Gageº and ªEngine Overheatingº in the
Index for further information.
Engine Overheated
This message is displayed
when the cooling system
temperature gets too hot.
This message will be displayed after the air conditioning
system has automatically turned off for the engine
coolant protection mode. See ªEngine Overheatingº in
the Index for further information.
Reduced Engine Power
This message is displayed
when the cooling system
temperature gets too hot
and the engine further
enters the engine coolant
protection mode.
See ªEngine Overheatingº in the Index for
further information.

2-82 Change Engine Oil
This message is displayed
when the engine oil needs
to be changed. The message
is only displayed for
15 seconds at the start of
each ignition cycle.
When you change the engine oil, be sure to reset the
Engine Oil Life Monitor. See ªEngine Oil, When to
Changeº in the Index.
Security
This message is displayed
when the content
theft
-deterrent system
has been activated and
also monitors the
Passlock

system.
If the security message is displayed continuously while
driving and stays on, there may be a problem with the
Passlock system. Your vehicle will not be protected by
Passlock, and you should see your GM dealer.
Low Washer Fluid
This message is displayed
when the vehicle is low on
windshield washer fluid.
The message is only
displayed for 15 seconds
each ignition cycle.
For more information, see ªWindshield Washer Fluidº in
the Index.
Service Ride Control
This message is
displayed when a possible
problem exists with the
Autoride system.
For more information, see ªAutorideº in the Index.

3-27
After you clean the player, press and hold the EJECT
button for five seconds to reset the CLN indicator. The
radio will display
--- to show the indicator was reset.
Cassettes are subject to wear and the sound quality
may degrade over time. Always make sure the cassette
tape is in good condition before you have your tape
player serviced.
Care of Your Compact Discs
Handle discs carefully. Store them in their original cases
or other protective cases and away from direct sunlight
and dust. If the surface of a disc is soiled, dampen a
clean, soft cloth in a mild, neutral detergent solution and
clean it, wiping from the center to the edge.
Be sure never to touch the signal surface when handling
discs. Pick up discs by grasping the outer edges or the
edge of the hole and the outer edge.
Care of Your Compact Disc Player
The use of CD lens cleaner discs is not advised, due to
the risk of contaminating the lens of the CD optics with
lubricants internal to the CD mechanism.
Fixed Mast Antenna
The fixed mast antenna can withstand most car washes
without being damaged. If the mast should ever become
slightly bent, you can straighten it out by hand. If the
mast is badly bent, as it might be by vandals, you should
replace it.
Check every once in a while to be sure the mast is still
tightened to the cowl. If tightening is required, tighten
by hand, then with a wrench one quarter turn.

4-14
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'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 ªmirrored surfaceº
-- and slow
down when you have any doubt.
Remember: Any anti
-lock brake system (ABS) helps
avoid only the braking skid.
Operating Your All-Wheel-Drive
Vehicle Off Paved Roads
Many of the same design features that help make your
vehicle responsive on paved roads during poor weather
conditions
-- features like the locking rear axle and
all
-wheel drive -- help make it much better suited for
off
-road use than a conventional passenger car. Its higher
ground clearance also helps your vehicle step over some
off
-road obstacles. But your vehicle doesn't have features
like special underbody shielding and a transfer case low
gear range, things that are usually thought necessary for
extended or severe off
-road service. This guide is for
operating your vehicle off paved roads.
Also, see ªAnti
-Lock Brakesº in the Index.
Off
-road driving can be great fun. But it does have some
definite hazards. The greatest of these is the terrain itself.
ªOff
-roadingº 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'll
find many driving tips and suggestions. These will help
make your off
-road driving safer and more enjoyable.

4-15 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 (if so equipped) are properly attached. Is there
enough fuel? Is the spare tire fully inflated? Are the
fluid levels up where they should be? What are the local
laws that apply to off
-roading where you'll be driving?
If you don't 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
There are some important things to remember about
how to load your vehicle.

The heaviest things should be on the load floor and
forward of your rear axle. Put heavier items as far
forward as you can.

Be sure the load is secured properly, so driving on
the off
-road terrain doesn't toss things around.
CAUTION:

Cargo on the load floor 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 floor can
be tossed about when driving over rough
terrain. You or your passengers can be
struck by flying 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.
You'll find other important information in this manual.
See ªVehicle Loading,º ªLuggage Carrierº and ªTiresº
in the Index.

4-27
If the water isn't too deep, then drive through it slowly. At
fast 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.
See ªDriving Through Waterº in the Index for more
information on driving through water.
After Off-Road Driving
Remove any brush or debris that has collected on the
underbody, chassis or under the hood. These
accumulations can be a fire hazard.
After operation in mud or sand, have the brake linings
cleaned and checked. These substances can cause
glazing and uneven braking. Check the body structure,
steering, suspension, wheels, tires and exhaust system
for damage. Also, check the fuel lines and cooling
system for any leakage.
Your vehicle will require more frequent service due to
off
-road use. Refer to the Maintenance Schedule for
additional information.