2004 GMC SIERRA DENALI Owners Manual

Trailer Wiring Harness
Your pickup is equipped with the eight-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, slide-in camper or cap.The eight-wire harness contains the following trailer
circuits:
·Yellow: Left Stop/Turn Signal
·Dark Green: Right Stop/Turn Signal
·Brown: Taillamps
·White: Ground
·Light Green: Back-up Lamps
·Light Blue: Center High-Mounted
Stoplamp (CHMSL)
·Red: Battery Feed
·Dark Blue: Trailer Brake
If your trailer is equipped with electrical brakes, you can
get a jumper harness/electric trailer brake control
with a trailer battery feed fuse from your dealer. This
harness and fuse should be installed by your dealer or a
quali®ed service center.
If you need to tow a light-duty trailer with a standard
four-way round pin connector, you can also get an
adapter from your dealer.
4-69

Instrument Panel Jumper Wiring Harness
{CAUTION:
Be sure to use only the correct trailer brake
harness, the one intended for use on your
vehicle. If you use some other trailer brake
harness, even if it seems to ®t, your trailer
brakes may not work at all. You could have a
crash in which you or others could be injured.
Use only the trailer brake harness intended for
your vehicle. If it is no longer available to you,
be sure to get a proper replacement from your
dealer.This harness is included with your vehicle as part of the
heavy-duty trailer wiring package.
This harness is for an electric brake controller and
includes a trailer battery feed fuse. It should be installed
by your dealer or a quali®ed service center.
4-70

Four-Wire Harness Adapter
This adapter is included
with your vehicle as part of
the heavy-duty trailer
wiring package.
Use this adapter to connect a standard four-way round
pin connector to the seven-wire harness on your
vehicle.Connect the adapter with the tab pointing up
(see arrow). The ¯ip cap on the vehicle's seven-wire
harness will lock onto the tab and help hold the adapter
in place. Plug the four-way round pin connector onto
the adapter.
4-71

-NOTES
4-72

Service............................................................5-3
Doing Your Own Service Work.........................5-3
Adding Equipment to the Outside of Your
Vehicle......................................................5-4
Fuel................................................................5-4
Gasoline Octane............................................5-4
Gasoline Speci®cations....................................5-4
California Fuel...............................................5-5
Additives.......................................................5-5
Fuels in Foreign Countries...............................5-6
Filling Your Tank............................................5-6
Filling a Portable Fuel Container.......................5-8
Checking Things Under the Hood.....................5-8
Hood Release................................................5-9
Engine Compartment Overview.......................5-10
Engine Oil...................................................5-11
Engine Air Cleaner/Filter................................5-16
Automatic Transmission Fluid.........................5-18
Engine Coolant.............................................5-21
Coolant Surge Tank Pressure Cap..................5-24
Engine Overheating.......................................5-25
Cooling System............................................5-28Engine Fan Noise.........................................5-34
Power Steering Fluid.....................................5-34
Windshield Washer Fluid................................5-35
Brakes........................................................5-36
Battery........................................................5-40
Jump Starting...............................................5-41
All-Wheel Drive..............................................5-46
Rear Axle.......................................................5-47
Front Axle......................................................5-48
Bulb Replacement..........................................5-49
Halogen Bulbs..............................................5-49
Headlamps..................................................5-49
Front Turn Signal, Sidemarker and Daytime
Running Lamps.........................................5-50
Roof Marker Lamps......................................5-52
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp.............................................5-54
Pickup Box Identi®cation and Fender
Marker Lamps...........................................5-55
Taillamps.....................................................5-56
Replacement Bulbs.......................................5-57
Section 5 Service and Appearance Care
5-1

Windshield Wiper Blade Replacement..............5-58
Tires..............................................................5-59
In¯ation - Tire Pressure.................................5-67
Tire Inspection and Rotation...........................5-68
When It Is Time for New Tires.......................5-69
Buying New Tires.........................................5-70
Uniform Tire Quality Grading..........................5-71
Wheel Alignment and Tire Balance..................5-72
Wheel Replacement......................................5-73
Tire Chains..................................................5-74
If a Tire Goes Flat........................................5-75
Changing a Flat Tire.....................................5-76
Spare Tire...................................................5-95
Appearance Care............................................5-96
Cleaning the Inside of Your Vehicle.................5-96
Care of Safety Belts......................................5-98
Weatherstrips...............................................5-98Cleaning the Outside of Your Vehicle..............5-99
Sheet Metal Damage...................................5-101
Finish Damage...........................................5-102
Underbody Maintenance...............................5-102
Chemical Paint Spotting...............................5-102
Vehicle Care/Appearance Materials................5-103
Vehicle Identi®cation.....................................5-104
Vehicle Identi®cation Number (VIN)................5-104
Service Parts Identi®cation Label...................5-104
Electrical System..........................................5-105
Windshield Wiper Fuses...............................5-105
Power Windows and Other Power Options......5-105
Fuses and Circuit Breakers..........................5-105
Capacities and Speci®cations........................5-114
Section 5 Service and Appearance Care
5-2

Service
Your dealer knows your vehicle best and wants you to
be happy with it. We hope you will go to your dealer
for all your service needs. You will get genuine GM parts
and GM-trained and supported service people.
We hope you will 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
will want to use the proper service manual. It tells
you much more about how to service your vehicle than
this manual can. To order the proper service manual,
see
Service Publications Ordering Information on
page 7-11.
Your vehicle has an air bag system. Before attempting
to do your own service work, see
Servicing Your Air
Bag-Equipped Vehicle on page 1-78.
You should keep a record with all parts receipts and list
the mileage and the date of any service work you
perform. See
Maintenance Record on page 6-16.
{CAUTION:
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.
CAUTION: (Continued)
5-3

CAUTION: (Continued)
·
Be sure to use the proper nuts, bolts and
other fasteners. ªEnglishº and ªmetricº
fasteners can be easily confused. If you
use the wrong fasteners, parts can later
break or fall off. You could be hurt.
Adding Equipment to the Outside of
Your Vehicle
Things you might add to the outside of your vehicle can
affect the air¯ow 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.
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 Speci®cations
It is recommended that gasoline meet speci®cations
which were developed by automobile manufacturers
around the world and contained in the World-Wide Fuel
Charter which is available from the Alliance of
Automobile Manufacturers at www.autoalliance.org.
Gasoline meeting these speci®cations could provide
improved driveability and emission control system
performance compared to other gasoline.
5-4