2004 GMC SIERRA fuel cap

Seats and Restraint Systems........................... 1-1
Front Seats
............................................... 1-3
Rear Seats
............................................... 1-9
Safety Belts
.............................................1-11
Child Restraints
.......................................1-33
Air Bag Systems
......................................1-70
Restraint System Check
............................1-87
Features and Controls..................................... 2-1
Keys
........................................................ 2-3
Doors and Locks
....................................... 2-8
Windows
.................................................2-16
Theft-Deterrent Systems
............................2-19
Starting and Operating Your Vehicle
...........2-21
Mirrors
....................................................2-54
OnStar
žSystem
......................................2-64
Storage Areas
.........................................2-66
Vehicle Personalization
.............................2-69
Instrument Panel............................................. 3-1
Instrument Panel Overview
.......................... 3-4
Climate Controls
......................................3-21
Warning Lights, Gages and Indicators
.........3-33
Driver Information Center (DIC)
..................3-55
Audio System(s)
.......................................3-73Driving Your Vehicle....................................... 4-1
Your Driving, the Road, and Your Vehicle
..... 4-2
Towing
...................................................4-53
Service and Appearance Care.......................... 5-1
Service
..................................................... 5-3
Fuel
......................................................... 5-4
Checking Things Under the Hood
...............5-10
Rear Axle
...............................................5-59
Four-Wheel Drive
.....................................5-60
Noise Control System
...............................5-62
Bulb Replacement
....................................5-64
Windshield Wiper Blade Replacement
.........5-74
Tires
......................................................5-76
Appearance Care
...................................5-116
Vehicle Identi®cation
...............................5-125
Electrical System
....................................5-125
Capacities and Speci®cations
...................5-134
Maintenance Schedule..................................... 6-1
Maintenance Schedule
................................ 6-2
Customer Assistance and Information.............. 7-1
Customer Assistance and Information
........... 7-2
Reporting Safety Defects
...........................7-11
Index................................................................ 1
2004 GMC Sierra Owner ManualM

This light should come on, as a check to show you it is
working, when the ignition is on and the engine is
not running. If the light does not come on, have it
repaired. This light will also come on during a
malfunction in one of two ways:
·Light FlashingÐ A mis®re condition has been
detected. A mis®re increases vehicle emissions
and may damage the emission control system on
your vehicle. Diagnosis and service may be
required.
·Light On SteadyÐ An emission control system
malfunction has been detected on your vehicle.
Diagnosis and service may be required.
If the Light is Flashing
The following may prevent more serious damage to
your vehicle:
·Reducing vehicle speed.
·Avoiding hard accelerations.
·Avoiding steep uphill grades.
·If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.
If the light stops ¯ashing and remains on steady, see ªIf
the Light Is On Steadyº following.If the light continues to ¯ash, when it is safe to do so,
stop the vehicle.Find a safe place to park your vehicle.
Turn the key off, wait at least 10 seconds and restart
the engine. If the light remains on steady, see
ªIf the Light Is On Steadyº following. If the light is still
¯ashing, follow the previous steps, and see your dealer
for service as soon as possible.
If the Light Is On Steady
You may be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully install
the cap. See
Filling Your Tank on page 5-7. The
diagnostic system can determine if the fuel cap has
been left off or improperly installed. A loose or missing
fuel cap will allow fuel to evaporate into the atmosphere.
A few driving trips with the cap properly installed
should turn the light off.
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.
3-50

Fuel Gage
When the ignition is on, the fuel gage tells you about
how much fuel you have left in your tank.
The gage will ®rst indicate empty before you are out of
fuel, and you should get more fuel as soon as
possible.
When the fuel tank is low the Low Fuel message will
appear. See
Driver Information Center (DIC) on
page 3-55.Here are some situations you may experience with your
fuel gage. None of these indicate a problem with the
fuel gage.
·At the gas station, the fuel pump shuts off before
the gage reads full.
·It takes a little more or less fuel to ®ll up than the
fuel gage indicated. For example, the gage may
have indicated the tank was half full, but it actually
took a little more or less than half the tank's
capacity to ®ll the tank.
·The gage goes back to empty when you turn off the
ignition.
If you have a diesel engine, see
Fuel Gage on
page 3-54in the Diesel Engine Supplement.
Low Fuel Warning Light
The light next to the fuel gage will come on brie¯y when
you are starting the engine.
This light comes on when the fuel tank is low on fuel.
To turn it off, add fuel to the fuel tank. See
Fuel on
page 5-4. United States
Canada
3-54

TIGHTEN FUEL CAP
If the vehicle's fuel cap is not tightened properly thsi
message may appear along with the check engine light
on the instrument panel. See
Malfunction Indicator
Lamp on page 3-49. Fully reinstall the fuel cap.
SeeFilling Your Tank on page 5-7. The diagnostic
system can determine if the fuel cap has been left off or
improperly installed. A loose or missing fuel cap will
allow fuel to evaporate into the atmosphere. A few
driving trips with the cap properly installed should turn
the light and message off.
TRACTION ACTIVE
When the traction control system had detected that any
of the vehicle's wheels are slipping, the traction
control system will activate and this message will appear
on the DIC. For more information see ªTraction Assistº
in the Index.
TRANSMISSION HOT
If the transmission ¯uid temperature becomes high, the
message center will display this message.
When the transmission enters the protection mode, you
may notice a change in the transmission shifting
patterns. When the transmission ¯uid temperature
returns to normal, the display will turn off and the
transmission shifting patterns will return to normal.
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 transmission
temperature warning is displayed.
The following situations can cause the transmission to
operate at higher temperatures:
·Towing a trailer
·Hot outside air temperatures
·Hauling a large or heavy load
·Low transmission ¯uid level
·High transmission ¯uid level
·Restricted air ¯ow to the radiator and the auxiliary
transmission oil cooler.
A temporary solution to hotter transmission operating
temperatures may be to let the transmission cool down.
If the transmission is operated at higher temperatures
on a frequent basis, see
Scheduled Maintenance
on page 6-4for the proper transmission maintenance
intervals.
3-72

Certi®cation/Tire Label
The Certi®cation/Tire label is found on the rear edge of
the driver's door.
The label shows the size of your original tires and the
in¯ation pressures needed to obtain the gross weight
capacity of your vehicle. This is called the GVWR (Gross
Vehicle Weight Rating). The GVWR includes the
weight of the vehicle, all occupants, fuel and cargo.The Certi®cation/Tire label also tells you the maximum
weights for the front and rear axles, called Gross
Axle Weight Rating (GAWR). To ®nd out the actual loads
on your front and rear axles, you need to go to a
weigh station and weigh your vehicle. Your dealer can
help you with this. Be sure to spread out your load
equally on both sides of the centerline.
Never exceed the GVWR for your vehicle, or the GAWR
for either the front or rear axle.
The Certi®cation/Tire label also contains important
information about your Front Axle Reserve Capacity.
See ªFront Axle Reserve Capacityº later in this section.
And, if you do have a heavy load, you should spread
it out.{CAUTION:
In the case of a sudden stop or collision,
things carried in the bed of your truck could
shift forward and come into the passenger
area, injuring you and others. If you put things
in the bed of your truck, you should make sure
they are properly secured.
4-61

Here are some guidelines for safely carrying a snow
plow on your vehicle:
·Make sure the weight on the front and rear axles
does not exceed the axle rating for each.
·For the front axle, if more cargo or passengers
must be carried, appropriate counter ballast must be
installed rear of the rear axle. Counter ballast
must be properly secured so it will not move during
driving.
·Follow the snow plow manufacturer's
recommendations regarding rear ballast. Rear
ballast may be required to ensure a proper front and
rear weight distribution ratio, even though the
actual weight at the front axle may be less than the
front axle rating.
·The snow plow manufacturer or installer can assist
you in determining the amount of rear ballast
required, to help make sure your snowplow/vehicle
combination does not exceed the GVW rating,
the front and rear axle ratings, and the front and
rear weight distribution ratio.
·The total vehicle must not exceed the GVW rating.
Q:What is front axle reserve capacity, and how do
I calculate it?
A:Front axle reserve capacity is the difference
between your front GAWR and the front axle
weight of your truck with full fuel and passengers.
Basically, it is the amount of weight you can
add to your front axle before reaching your
front GAWR.
The front axle reserve capacity for your vehicle can be
found in the lower right corner of the Certi®cation/Tire
label, as shown.
United States
Canada
4-65

{CAUTION:
On some vehicles equipped with certain front
mounted equipment, such as a snow plow, it
may be possible to load the front axle to the
front GAWR but not have enough weight on
the rear axle to have proper braking
performance. If your brakes can not work
properly, you could have a crash. To help your
brakes work properly when a snow plow is
installed, always follow the snow plow
manufacturer or installer's recommendation for
rear ballast to ensure a proper front and rear
weight distribution ratio, even though the
actual front weight may be less than the front
GAWR, and the total vehicle weight is less
than the GVWR. Maintaining a proper front and
rear weight distribution ratio is necessary to
provide proper braking performance.
Q:What is total vehicle reserve capacity?
A:This is the difference between your GVWR and
the weight of your truck with full fuel and
passengers. It is the amount of weight you can
add to your vehicle before reaching your GVWR.
Keep in mind that reserve capacity numbers
are intended as a guide when selecting the amount
of equipment or cargo your truck can carry. If
you are unsure of your truck's front, rear or total
weight, go to a weigh station and weigh your
vehicle. Your dealer can also help you with this.
The total vehicle reserve capacity for your vehicle
can be found in the lower right corner of the
Certi®cation/Tire label as shown previously.
See your dealer for additional advice and information
about using a snow plow on your vehicle. Also,
see
Loading Your Vehicle on page 4-57.
4-67

To identify the vehicle trailering capacity of your vehicle,
you should read the information in ªWeight of the
Trailerº that appears later in this section.
If yours was built with trailering options, as many are,
it's ready for heavier trailers. But trailering is different
than just driving your vehicle by itself. Trailering means
changes in acceleration, braking, handling, durability
and fuel economy. Successful, safe trailering takes
correct equipment, and it has to be used properly.
That's the reason for this part. In it are many time-tested,
important trailering tips and safety rules. Many of
these are important for your safety and that of your
passengers. So please read this section carefully before
you pull a trailer.
If You Do Decide To Pull A Trailer
If you do, here are some important points:
·There are many different laws, including speed limit
restrictions, having to do with trailering. Make sure
your rig will be legal, not only where you live
but also where you'll be driving. A good source for
this information can be state or provincial police.
·Consider using a sway control. See ªHitchesº later
in this section.
·Don't tow a trailer at all during the ®rst 500 miles
(800 km) your new vehicle is driven. Your engine,
axle or other parts could be damaged.
·Then, during the ®rst 500 miles (800 km) that you
tow a trailer, don't drive over 50 mph (80 km/h)
and don't make starts at full throttle. This helps your
engine and other parts of your vehicle wear in at
the heavier loads.
·If you have an automatic transmission, you can tow
in DRIVE (D). You may want to shift the
transmission to THIRD (3) or, if necessary, a lower
gear selection if the transmission shifts too often,
such as under heavy loads and/or hilly conditions. If
you have a manual transmission and you are
towing a trailer, it's better not to use the highest
gear. See
Tow/Haul Mode Light on page 3-53.
Three important considerations have to do with weight:
·The weight of the trailer
·The weight of the trailer tongue
·The weight on your vehicle's tires
4-71