2004 GMC SIERRA towing

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

{CAUTION:
If the air bag readiness light in the instrument
panel cluster ever comes on and stays on, it
means that something may be wrong with the
air bag system. If this ever happens, have the
CAUTION: (Continued)
CAUTION: (Continued)
vehicle serviced promptly, because an
adult-size person sitting in the right front
passenger's seat may not have the protection
of the frontal air bag. See ªAir Bag Readiness
Lightº in the Index for more on this, including
important safety information.
Aftermarket equipment, such as seat covers, can affect
how well the passenger sensing system operates.
You may want to consider not using seat covers or other
aftermarket equipment if your vehicle has the passenger
sensing system. See
Adding Equipment to Your Air
Bag-Equipped Vehicle on page 1-86for more
information about modi®cations that can affect how the
system operates.
{CAUTION:
Stowing of articles under the passenger's seat
or between the passenger's seat cushion and
seatback may interfere with the proper
operation of the passenger sensing system.
1-85

Passlockž
Your vehicle is equipped with the
Passlockžtheft-deterrent system.
Passlockžis a passive theft-deterrent system.
Passlockženables fuel if the ignition lock cylinder is
turned with a valid key. If a correct key is not used or the
ignition lock cylinder is tampered with, fuel is disabled.
If the engine stalls and the security light ¯ashes, wait until
the light stops ¯ashing before trying to restart the engine.
Remember to release the key from START as soon as
the engine starts.
If the engine is running and the security light comes on,
you will be able to restart the engine if you turn the engine
off. However, your Passlock
žsystem is not working
properly and must be serviced by your dealer. Your
vehicle is not protected by Passlock
žat this time. You
may also want to check the fuse. SeeFuses and Circuit
Breakers on page 5-126. See your dealer for service.
In an emergency, call the GM Roadside Assistance
Center. See
Roadside Assistance Program on page 7-6.
Starting and Operating Your
Vehicle
New Vehicle Break-In
Notice:Your vehicle does not need an elaborate
ªbreak-in.º But it will perform better in the long run
if you follow these guidelines:
·Keep your speed at 55 mph (88 km/h) or less for
the ®rst 500 miles (805 km).
·Do not drive at any one speed Ð fast or
slow Ð for the ®rst 500 miles (805 km). Do not
make full-throttle starts.
·Avoid making hard stops for the ®rst 200 miles
(322 km) or so. During this time your new brake
linings are not yet broken in. Hard stops with new
linings can mean premature wear and earlier
replacement. Follow this breaking-in guideline
every time you get new brake linings.
·Do not tow a trailer during break-in. SeeTowing a
Trailer on page 4-70
for more information.
2-21

How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead
of trying to list everything here, we ask that you contact
your dealer in the area where you'll be parking your
vehicle. The dealer can give you the best advice for that
particular area.
Automatic Transmission Operation
If your vehicle is equipped with an automatic
transmission, it features an electronic shift position
indicator within the instrument panel cluster. This display
must be powered anytime the shift lever is capable of
being moved out of PARK (P). See
Fuses and
Circuit Breakers on page 5-126.
There are several different positions for your shift lever.
PARK (P):This position locks your rear wheels. It's
the best position to use when you start your engine
because your vehicle can't move easily. If your vehicle
is equipped with the Allison
žTransmission, use
PARK (P) for stationary operation of the Power Takeoff
(PTO), if equipped.
{CAUTION:
It is dangerous to get out of your vehicle if the
shift lever is not fully in PARK (P) with the
parking brake ®rmly set. Your vehicle can roll.
Do not leave your vehicle when the engine is
running unless you have to. If you have left the
engine running, the vehicle can move
suddenly. You or others could be injured. To
be sure your vehicle will not move, even when
you are on fairly level ground, always set your
parking brake and move the shift lever to
PARK (P). See
Shifting Into Park (P) on
page 2-49
. If you are pulling a trailer, see
Towing a Trailer on page 4-70.
2-26

DRIVE (D):This position is for normal driving. If you
need more power for passing, and you're:
·Going less than about 35 mph (55 km/h), push your
accelerator pedal about halfway down.
·Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
You'll shift down to the next gear and have more power.
Drive (D) can be used when towing a trailer, carrying
a heavy load, driving on steep hills or for off-road driving.
You may want to shift the transmission to THIRD (3)
or, if necessary, a lower gear selection if the
transmission shifts too often.
Notice:Extended idling for more than ®ve minutes
in DRIVE (D) on vehicles equipped with the Allison
Transmission may cause transmission overheating
and damage. Always put the gearshift lever in
PARK (P) if idle time is longer than ®ve minutes.
If your vehicle is equipped with the Allison
ž
Transmission, it will initially attain ®rst range when
DRIVE (D) is selected. As vehicle speed increases, the
transmission will upshift automatically through each
available range up to FIFTH (5). As the vehicle slows,
the transmission will downshift automatically.
THIRD (3):This position is also used for normal driving,
however it offers more power and lower fuel economy
than DRIVE (D).SECOND (2):This position gives you more power but
lower fuel economy. You can use SECOND (2) on
hills. It can help control your speed as you go down
steep mountain roads, but then you would also want to
use your brakes off and on.
If you manually select SECOND (2) in a light duty
automatic transmission, the transmission will drive in
second gear. You may use this feature for reducing the
speed of the rear wheels when you are trying to start
your vehicle from a stop on slippery road surfaces.
FIRST (1):This position gives you even more power
(but lower fuel economy) than SECOND (2). You
can use it on very steep hills, or in deep snow or mud.
If the selector lever is put in FIRST (1) while the
vehicle is moving forward, the transmission won't shift
into ®rst gear until the vehicle is going slowly enough.
Notice:Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator
pedal may damage the transmission. If you are
stuck, do not spin the tires. When stopping on a hill,
use the brakes to hold the vehicle in place.
On cold days, approximately 32ÉF (0ÉC) or colder, your
transmission is designed to shift differently until the
engine reaches normal operating temperature. This is
intended to improve heater performance.
2-28

Tow/Haul Mode
(Automatic Transmission)
Your vehicle may be equipped with a Tow/Haul mode.
The selector button is located on the end of the
column shift lever. You can use this feature to assist
when towing or hauling a heavy load. Turn Tow/Haul on
and off by pressing the button until the Tow/Haul
indicator light illuminates on the instrument panel. See
ªTow/Haul Mode²under
Towing a Trailer on page 4-70for more information.
Overdrive Disable
(Allison Transmissionž)
If your vehicle has an Allison Transmissionžyou may
have the overdrive disable feature. The overdrive disable
feature prevents the transmission from shifting into
®fth (5) gear. The selector button is located on the end of
the column shift lever. You can turn overdrive disable on
and off by pressing and holding the button at the end of
the column shift lever until the indicator light, on the
instrument panel, illuminates.
2-29

If your vehicle has both Tow/Haul and overdrive disable
tap the button once to enable or disable Tow/Haul, and
press and hold the button to enable or disable overdrive
disable.
Manual Transmission Operation
Five-Speed
(VORTECŸ 6000 V8 Engine)
Here's how to operate your
transmission.
FIRST (1) is intended only for heavy loads or trailer
towing and is not recommended for normal driving.
During the ®rst 500 miles (805 km) of vehicle use, start
your vehicle moving in FIRST (1). This allows clutch
components to break-in properly.FIRST (1):Press the clutch pedal and shift into
FIRST (1). Then, slowly let up on the clutch pedal as
you press the accelerator pedal. Shift into FIRST (1)
only when the vehicle is below 5 mph (8 km/h). If you try
to shift down into FIRST (1) at excessive vehicle
speeds, the shift lever will not move into FIRST (1) until
vehicle speed is reduced.
SECOND (2):Press the clutch pedal and shift into
SECOND (2). Then, slowly let up on the clutch pedal as
you press the accelerator pedal.
You can shift into SECOND (2) when you're going less
than 20 mph (32 km/h). If you've come to a complete
stop and it's hard to shift into SECOND (2), put the shift
lever into NEUTRAL and let up on the clutch. Press
the clutch pedal back down. Then shift into
SECOND (2). If you try to downshift into SECOND (2) at
excessive vehicle speeds, the shift lever will not move
into the SECOND (2) position until the vehicle speed
is reduced.
THIRD (3):Press the clutch pedal and shift into
THIRD (3). Then, slowly let up on the clutch pedal as
you press the accelerator pedal.
2-30

THIRD (3), FOURTH (4) and FIFTH (5):Shift into
THIRD (3), FOURTH (4) and FIFTH (5) the same way
you do for SECOND (2). Slowly let up on the clutch
pedal as you press the accelerator pedal.
To stop, let up on the accelerator pedal and press the
brake pedal. Just before the vehicle stops, press
the clutch pedal and the brake pedal, and shift to
NEUTRAL.
NEUTRAL:Use this position when you start or idle
your engine.
REVERSE (R):To back up, ®rst press down the clutch
pedal. Wait for the vehicle to stop moving and then,
shift into REVERSE (R). Let up on the clutch pedal
slowly while pressing the accelerator pedal.
Notice:Shifting to REVERSE (R) while your vehicle
is moving forward could damage the transmission.
The repairs would not be covered by your warranty.
Shift to REVERSE (R) only after your vehicle is
stopped.
Also, use REVERSE (R), along with the parking brake,
when turning off your engine and parking your
vehicle.
Six-Speed (VORTECŸ 8100 V8 and
DURAMAXŸ 6600 V8 Engines)
Here's how to operate your
transmission.
This six-speed pattern is unique to GM manual
transmissions. The transmission always repositions the
shift lever to NEUTRAL, which is located between
FOURTH (4) and FIFTH (5) gear.
To prevent unintentional gear selections, additional
force is required to move the shift lever into
REVERSE (R) or FIRST (1). Use FIRST (1) when trailer
towing, driving with payload in the pickup box or
launching on a grade. Otherwise, start in SECOND (2)
gear. Only shift into FIRST (1) when the vehicle has
stopped moving.
2-32