2002 GMC YUKON XL service

6-20Automatic Transmission Fluid When to Check and Change A good time to check your automatic transmission fluid
level is when the engine oil is changed.
Change both the fluid and filter every 50,000 miles
(83 000 km) if the vehicle is mainly driven under one or
more of these conditions:

In heavy city traffic where the outside temperature
regularly reaches 90  F (32  C) or higher.

In hilly or mountainous terrain.

When doing frequent trailer towing.

Uses such as found in taxi, police or delivery service.
If you do not use your vehicle under any of
these conditions, change the fluid and filter
every 100,000 miles (166 000 km).
See ªScheduled Maintenance Servicesº in the Index. How to Check Because this operation can be a little difficult, you
may choose to have this done at the dealership
service department.
If you do it yourself, be sure to follow all the
instructions here, or you could get a false reading
on the dipstick.
NOTICE: Too much or too little fluid can damage your
transmission. Too much can mean that some of
the fluid could come out and fall on hot engine
parts or exhaust system parts, starting a fire.
Too little fluid could cause the transmission to
overheat. Be sure to get an accurate reading if
you check your transmission fluid.

6-23How to Add Fluid Refer to the Maintenance Schedule to determine what
kind of transmission fluid to use. See ªRecommended
Fluids and Lubricantsº in the Index.
Add fluid only after checking the transmission fluid
while it is hot. (A cold check is used only as a
reference.) If the fluid level is low, add only enough of
the proper fluid to bring the level up to the HOT area for
a hot check. It doesn't take much fluid, generally less
than one pint (0.5 L). Don't overfill.
NOTICE: We recommend you use only fluid labeled
DEXRON 
- III, because fluid with that label is
made especially for your automatic transmission.
Damage caused by fluid other than DEXRON 
- III
is not covered by your new vehicle warranty.

After adding fluid, recheck the fluid level as
described under ªHow to Check.º

When the correct fluid level is obtained, push the
dipstick back in all the way; then flip the handle
down to lock the dipstick in place. Rear Axle When to Check Lubricant Refer to the Maintenance Schedule to determine how
often to check the lubricant. See ªScheduled
Maintenance Servicesº in the Index.
How to Check Lubricant
To get an accurate reading, the vehicle should be on a
level surface.
The proper level is from 5/8 inch to 1 5/8 inch
(15 mm to 40 mm) below the bottom of the filler plug
hole. Add only enough fluid to reach the proper level.

6-25What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See ªRecommended Fluids and
Lubricantsº in the Index.
Front Axle When to Check and Change Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant and when to change it. See
ªScheduled Maintenance Servicesº in the Index. How to Check Lubricant
To get an accurate reading, the vehicle should be on a
level surface.
If the level is below the bottom of the filler plug hole,
you may need to add some lubricant.

6-35Brake Wear Your vehicle has four
- wheel disc brakes.
Disc brake pads have built
- in wear indicators that
make a high
- pitched warning sound when the brake
pads are worn and new pads are needed. The sound
may come and go or be heard all the time your vehicle
is moving (except when you are pushing on the brake
pedal firmly).
CAUTION:The brake wear warning sound means that soon
your brakes won't work well. That could lead to
an accident. When you hear the brake wear
warning sound, have your vehicle serviced.
NOTICE: Continuing to drive with worn
- out brake pads
could result in costly brake repair. Some driving conditions or climates may cause a brake
squeal when the brakes are first applied or lightly
applied. This does not mean something is wrong with
your brakes.
Properly torqued wheel nuts are necessary to help
prevent brake pulsation. When tires are rotated, inspect
brake pads for wear and evenly tighten wheel nuts in the
proper sequence to GM torque specifications.
Brake linings should always be replaced as complete
axle sets.
See ªBrake System Inspectionº in Section 7 of this manual
under Part C ªPeriodic Maintenance Inspections.º
Brake Pedal Travel See your dealer if the brake pedal does not return to
normal height, or if there is a rapid increase in pedal
travel. This could be a sign of brake trouble.
Brake Adjustment Every time you make a brake stop, your disc brakes
adjust for wear.

6-42Tires Your new vehicle comes with high
- quality tires made by
a leading tire manufacturer. If you ever have questions
about your tire warranty and where to obtain service,
see your GMC Warranty booklet for details.
CAUTION:Poorly maintained and improperly used tires
are dangerous.

Overloading your tires can cause
overheating as a result of too much friction.
You could have an air
- out and a serious
accident. See ªLoading Your Vehicleº in
the Index.
CAUTION: (Continued) CAUTION: (Continued)

Underinflated tires pose the same danger as
overloaded tires. The resulting accident
could cause serious injury. Check all tires
frequently to maintain the recommended
pressure. Tire pressure should be checked
when your tires are cold.

Overinflated tires are more likely to be
cut, punctured or broken by a sudden
impact
-- such as when you hit a pothole.
Keep tires at the recommended pressure.

Worn, old tires can cause accidents. If your
tread is badly worn, or if your tires have
been damaged, replace them.

6-44Tire Inspection and Rotation Tires should be rotated every 6,000 to 8,000 miles
(10 000 to 13 000 km). Any time you notice unusual
wear, rotate your tires as soon as possible and check
wheel alignment. Also check for damaged tires or
wheels. See ªWhen It's Time for New Tiresº and
ªWheel Replacementº later in this section for more
information. Make sure the spare tire is stored securely.
Push, pull, and then try to rotate or turn the tire. If it
moves, use the wheel wrench to tighten the cable. See
ªStoring a Flat or Spare Tire and Toolsº in the Index.
The purpose of regular rotation is to achieve more uniform
wear for all tires on the vehicle. The first rotation is the
most important. See ªScheduled Maintenance Servicesº in
the Index for scheduled rotation intervals. When rotating your tires, always use the correct rotation
pattern shown here. Don't include the spare tire in your
tire rotation.
After the tires have been rotated, adjust the front and rear
inflation pressures as shown on the Certification/Tire label.
Make certain that all wheel nuts are properly tightened.
See ªWheel Nut Torqueº in the Index.
CAUTION: Rust or dirt on a wheel, or on the parts to which
it is fastened, can make wheel nuts become loose
after a time. The wheel could come off and cause
an accident. When you change a wheel, remove
any rust or dirt from places where the wheel
attaches to the vehicle. In an emergency, you
can use a cloth or a paper towel to do this; but
be sure to use a scraper or wire brush later, if
you need to, to get all the rust or dirt off. See
ªChanging a Flat Tireº in the Index.

6-46Buying New Tires To find out what kind and size of tires you need, look at
the Certification/Tire label.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Specification (TPC Spec)
number on each tire's sidewall. When you get new tires,
get ones with that same TPC Spec number. That way
your vehicle will continue to have tires that are designed
to give proper endurance, handling, speed rating,
traction, ride and other things during normal service on
your vehicle. If your tires have an all
- season tread
design, the TPC number will be followed by an ªMSº
(for mud and snow).
If you ever replace your tires with those not having
a TPC Spec number, make sure they are the same
size, load range, speed rating and construction type
(bias, bias
- belted or radial) as your original tires. CAUTION: Mixing tires could cause you to lose control while
driving. If you mix tires of different sizes or types
(radial and bias
- belted tires), the vehicle may not
handle properly, and you could have a crash.
Using tires of different sizes may also cause
damage to your vehicle. Be sure to use the same
size and type tires on all wheels.
If your vehicle has 17 inch road tires (those
originally installed on your vehicle) it is all right
to drive with the 16 inch spare tire that came
with your vehicle. When new, your vehicle
included a spare tire and wheel assembly with the
same overall diameter as your vehicle's road tires
and wheels. Because this spare tire was developed
for use on your vehicle, it will not affect vehicle
handling or cause damage to your vehicle.

6-48 Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specified government test course.
For example, a tire graded 150 would wear one and
a half (1 1/2) 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 significantly 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 specified 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. Temperature
-- A, B, C
The temperature grades are A (the highest), B, and C,
representing the tire's resistance to the generation of
heat and its ability to dissipate heat when tested under
controlled conditions on a specified indoor laboratory
test wheel. Sustained high temperature can cause the
material of the tire to degenerate and reduce tire life, and
excessive temperature can lead to sudden tire failure.
The grade C corresponds to a level of performance
which all passenger car tires must meet under the
Federal Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of performance
on the laboratory test wheel than the minimum required
by law.
Warning: The temperature grade for this tire is
established for a tire that is properly inflated and not
overloaded. Excessive speed, underinflation, or
excessive loading, either separately or in combination,
can cause heat buildup and possible tire failure.