2003 GMC YUKON DENALI Owners Manual

Trailer Wiring Harness
Heavy-Duty Trailer Wiring Package
Your vehicle is equipped with the seven-wire trailer
towing harness. This harness with a seven-pin universal heavy-duty trailer connector
is attached to a bracket
on the hitch platform. The Center High-Mounted Stoplamp
(CHMSL) wire is
tied next
to the trailer wiring harness for use with a
trailer.
The seven-wire harness contains the following trailer
circuits:
0 Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
0 Red: Battery Feed
Dark Blue: Trailer Brake
4-56

Section 5 Service and Appearance Care
Service ............................................................ 5.3
Doing Your Own Service Work
......................... 5-3
Adding Equipment
to the Outside of Your
Vehicle
.................................................. 5-4
................................................................ Fuel 5.5
Gasoline Octane ............................................ 5.5
Gasoline Specifications ................................... 5-5
California Fuel ............................................... 5-6
Additives
....................................................... 5.6
Fuels in Foreign Countries
............................... 5-6
Filling Your Tank
............................................ 5-7
Filling a Portable Fuel Container ....................... 5.9
the Hood .................... , .................... 5.10
Hood Release ...................... ................ 5-10
Engine Compartment Overview ....... ......... 5-12
Engine Oil ....................................... ..... 5.13
Engine Air Cleaner/Filter ............................. 5.17
Automatic Transmission Fluid ......................... 5-20
Engine Coolant ......................................... 5-22
Checking Things Under
~~
Coolant Surge Tank Pressure Cap ............... 5-25
Engine Overheating ....................................... 5-25
Cooling System ............................................ 5.28
Engine Fan Noise ......................................... 5.33
Power Steering Fluid
..................................... 5-34
Windshield Washer Fluid
................................ 5.34
Brakes
........................................................ 5.36
Battery
........................................................ 5-39
Jump Starting
............................................... 5.40
All-Wheel Drive .............................................. 5.46
Rear Axle .................................. .......... 5-48
Bulb Replacement .......................................... 5-49
Halogen Bulbs .............................................. 5-49
Headlamps
.................................................. 5-49
Running Lamps
......................................... 5-50
Center High-Mounted Stoplamp (CHMSL) ......... 5-52
Taillamps ..................................................... 5-52
Replacement Bulbs ................................... 5.53
Front Turn Signal, Sidemarker and Daytime
5- 1

Section 5 Service and Appearance Care
Windshield Wiper Blade Replacement .............. 5.54
Tires .............................................................. 5.55
Inflation .. Tire Pressure ............................... 5-55
Tire Inspection and Rotation ........................... 5.56
When It
Is Time for New Tires ....................... 5-58
Buying New Tires
......................................... 5.58
Uniform Tire Quality Grading
.......................... 5.59
Wheel Alignment and Tire Balance
.................. 5-61
Wheel Replacement
...................................... 5.61
Tire Chains
.................................................. 5-62
If a Tire Goes Flat ........................................ 5.63
Spare Tire
................................................... 5.77
Appearance Care ............................................ 5.78
Cleaning the Inside of Your Vehicle
................. 5-78
Care of Safety Belts
...................................... 5.80
Weatherstrips
............................................... 5.80
Changing a Flat Tire
..................................... 5-63 Cleaning the Outside
of Your Vehicle
.............. 5-81
Sheet Metal Damage
.................................... 25-83
Finish Damage
............................................ 5-83
Underbody Maintenance
............................... 5-84
Chemical Paint Spotting
................................ 5-84
GM Vehicle Care/Appearance Materials
........... 5-84
Vehicle Identification .................................... ,.5-86
Service Parts Identification Label
..................... 5-86
Electrical System ............................................ 5-87
Add-on Electrical Equipment .......................... 5-87
Windshield Wiper Fuses
............................... 25-87
Power Windows
and Other Power Options ....... 5-87
Fuses and Circuit Breakers
............................ 5-87
Capacities and Specifications .......................... 5-96
Capacities and Specifications ......................... 5-96
Vehicle
Identification Number (VIN)
................ 5-86
Normal Maintenance Replacement Parts ...... 5-98
5-2

Service
Your dealer knows your vehicle best and wants you to
be happy with it. We hope you’ll go to your dealer
for all your service needs. You’ll get genuine
GM parts
and GM-trained and supported service people.
We hope you’ll want to keep your GM vehicle all GM.
Genuine GM parts have one of these marks:
Doing Your Own Service Work
If you want to do some of your own service work, you’ll
want to use the proper service manual. It tells you
much more about how to service your vehicie
than this
manual can. To order the proper service manual,
see Service Publications Ordering Information
on
page 7-10.
Your vehicle has an air bag system. Before attempting
to do your own service work, see Servicing Your Air
Bag-Equipped Vehicle on page
1-85.
You should keep a record with all parts receipts and list
the mileage and the date of any service work you
perform. See Part
E: Maintenance Record on page 6-17.
5-3

You can be injured and your vehicle could be
damaged if you try to do service work on a
vehicle without knowing enough about
it.
Be sure you have sufficient knowledge,
experience, the proper replacement parts and tools before you attempt any vehicle
maintenance task.
Be sure to use the proper nuts, bolts and
other fasteners. “English” and “metric”
fasteners can be easily confused.
If you
use the wrong fasteners, parts can later
break or fall
off. You could be hurt.
1
Adding Equipment to the Outside of
Your
Vehicle
Things you might add to the outside of your vehicle can
affect the airflow around it. This may cause wind
noise and affect windshield washer performance.
Check with your dealer before adding equipment
to the
outside of
your vehicle.
5-4

Fuel
Use of the recommended fuel is an important part of the
proper maintenance
of your vehicle.
Gasoline Octane
Use regular unleaded gasoline with a posted octane
of 87 or higher.
If the octane is less than 87, you may
get a heavy knocking noise when you drive. If this
occurs, use a gasoline rated at 87 octane or higher as
soon as possible. Otherwise, you might damage
your engine.
A little pinging noise when you accelerate
or drive uphill
is considered normal. This does not
indicate a problem exists or that a higher-octane fuel is
necessary. If you are using 87 octane or higher-octane
fuel and hear heavy knocking, your engine needs
service.
Gasoline Specifications
It is recommended that gasoline meet specifications
which were developed by the American Automobile
Manufacturers Association and endorsed
by the
Canadian Vehicle Manufacturers Association for better
vehicle performance and engine protection. Gasoline meeting these specifications could provide improved
driveability and emission control system performance
compared to other gasoline.
In Canada, look for the
"Auto Makers' Choice"
label on the pump.
Canada Only
5-5

California Fuel
If your vehicle is certified to meet California Emission
Standards (see the underhood emission control label), it
is designed
to operate on fuels that meet California
specifications.
If this fuel is not available in states
adopting California emissions standards, your vehicle
will operate satisfactorily on fuels meeting federal
specifications, but emission control system performance
may be affected. The malfunction indicator lamp may
turn on (see Malfunction Indicator Lamp on page
3-38 )
and your vehicle may fail a smog-check test. If this
occurs, return
to your authorized GM dealer for
diagnosis.
If it is determined that the condition is caused
by the type of fuel used, repairs may not be covered
by your warranty.
Additives
To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent engine and fuel system deposits from forming,
allowing your emission control system
to work
properly. You should not have
to add anything to your
fuel. Gasolines containing oxygenates, such as ethers and ethanol, and reformulated gasolines may be
available in your area to contribute
to clean air.
General Motors recommends that you use these
gasolines, particularly
if they comply with the
specifications described earlier.
5-6
Notice: Your vehicle was not designed for fuel that
contains methanol. Don’t use fuel containing
methanol. It can corrode metal parts in your fuel
system and also damage the plastic and rubber
parts. That damage wouldn’t be covered under your
warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask the attendant where you buy gasoline
whether the fuel contains MMT. General Motors does
not recommend the use of such gasolines. Fuels
containing MMT can reduce the life of spark plugs and
the performance of the emission control system may
be affected. The malfunction indicator lamp may turn on.
If this occurs, return to your authorized GM dealer for
service.
Fuels in Foreign Countries
If you plan on driving in another country outside the
United States or Canada, the proper fuel may be hard
to find. Never use leaded gasoline or any other fuel
not recommended in the previous text on fuel. Costly
repairs caused by use of improper fuel wouldn’t be
covered by your warranty.
To check the fuel availability, ask an auto club, or
contact a major oil company that does business in the
country where you’ll be driving.

Filling Your Tank
Fuel vapor is highly flammable. It burns
violently, and that can cause very bad injuries.
Don’t smoke
if you’re near fuel or refueling
your vehicle. Keep sparks, flames and smoking
materials away from
fuel.
The fuel cap is located behind a hinged door on the
driver’s side of the vehicle.
5-7