
Seats and Restraint Systems........................... 1-1
Front Seats
............................................... 1-2
Rear Seats
............................................... 1-6
Safety Belts
.............................................. 1-7
Child Restraints
.......................................1-29
Air Bag Systems
......................................1-55
Restraint System Check
............................1-71
Features and Controls..................................... 2-1
Keys
........................................................ 2-2
Doors and Locks
....................................... 2-6
Windows
.................................................2-11
Theft-Deterrent Systems
............................2-13
Starting and Operating Your Vehicle
...........2-15
Mirrors
....................................................2-28
OnStar
®System
......................................2-33
HomeLink®Transmitter
.............................2-35
Storage Areas
.........................................2-39
Vehicle Personalization
.............................2-41
Instrument Panel............................................. 3-1
Instrument Panel Overview
.......................... 3-2
Climate Controls
......................................3-18
Warning Lights, Gages and Indicators
.........3-24
Driver Information Center (DIC)
..................3-42
Audio System(s)
.......................................3-56Driving Your Vehicle....................................... 4-1
Your Driving, the Road, and Your Vehicle
..... 4-2
Towing
...................................................4-46
Service and Appearance Care.......................... 5-1
Service
..................................................... 5-3
Fuel
......................................................... 5-4
Checking Things Under
the Hood
.............................................5-10
All-Wheel Drive
........................................5-45
Rear Axle
...............................................5-46
Front Axle
...............................................5-47
Bulb Replacement
....................................5-48
Windshield Wiper Blade Replacement
.........5-56
Tires
......................................................5-56
Appearance Care
.....................................5-82
Vehicle Identi cation
.................................5-90
Electrical System
......................................5-91
Capacities and Speci cations
.....................5-99
Normal Maintenance Replacement Parts
....5-100
Maintenance Schedule..................................... 6-1
Maintenance Schedule
................................ 6-2
Customer Assistance Information.................... 7-1
Customer Assistance Information
.................. 7-2
Reporting Safety Defects
............................ 7-8
Index................................................................ 1
2003 GMC Sierra Denali Owner ManualM
2003 - Sierra Denali Owner Manual

A few crashes are mild, and some crashes can be so
serious that even buckled up, a person wouldn’t survive.
But most crashes are in between. In many of them,
people who buckle up can survive and sometimes walk
away. Without belts they could have been badly hurt
or killed.
After more than 30 years of safety belts in vehicles, the
facts are clear. In most crashes buckling up does
matter... a lot!Why Safety Belts Work
When you ride in or on anything, you go as fast
as it goes.
Take the simplest vehicle. Suppose it’s just a seat on
wheels.
1-8
2003 - Sierra Denali

Where Are the Air Bags?
The driver’s air bag is in the middle of the steering
wheel.The right front passenger’s air bag is in the instrument
panel on the passenger’s side.
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2003 - Sierra Denali

{CAUTION:
If something is between an occupant and an
air bag, the bag might not inflate properly or it
might force the object into that person causing
severe injury or even death. The path of an
inflating air bag must be kept clear. Don’t put
anything between an occupant and an air bag,
and don’t attach or put anything on the
steering wheel hub or on or near any other air
bag covering.
When Should an Air Bag Inflate?
An air bag is designed to inflate in a moderate to severe
frontal, or near-frontal crash. The air bag will inflate
only if the impact speed is above the system’s designed
“threshold level.”
In addition, your vehicle has“dual stage”frontal air
bags, which adjust the amount of restraint according to
crash severity. For moderate frontal impacts, these
air bags inflate at a level less than full deployment.For more severe frontal impacts, full deployment occurs.
If the front of your vehicle goes straight into a wall
that doesn’t move or deform, the threshold level for the
reduced deployment is about 10 to 16 mph
(16 to 25 km/h), and the threshold level for a full
deployment is about 20 to 25 mph (32 to 40 km/h).
The threshold level can vary, however, with specific
vehicle design, so that it can be somewhat above
or below this range.
If your vehicle strikes something that will move or
deform, such as a parked car, the threshold level will be
higher. The air bag is not designed to inflate in
rollovers, rear impacts, or in many side impacts because
inflation would not help the occupant.
In any particular crash, no one can say whether an air
bag should have inflated simply because of the damage
to a vehicle or because of what the repair costs were.
Inflation is determined by the angle of the impact
and how quickly the vehicle slows down in frontal or
near-frontal impacts.
The air bag system is designed to work properly under
a wide range of conditions, including off-road usage.
Observe safe driving speeds, especially on rough
terrain. As always, wear your safety belt. See“Off-Road
Driving”in the Index for more tips on off-road driving.
1-58
2003 - Sierra Denali

Seat Position Sensors
Vehicle’s with dual stage air bags are also equipped
with special sensors which enable the sensing system to
monitor the position of both the driver and passenger
front seats. The seat position sensor provides
information which is used to determine if the air bags
should deploy at a reduced level or at full depoyment.
What Makes an Air Bag Inflate?
In an impact of sufficient severity, the air bag sensing
system detects that the vehicle is in a crash. The
sensing system triggers a release of gas from the
inflator, which inflates the air bag. The inflator, air bag,
and related hardware are all part of the air bag
modules inside the steering wheel and in the instrument
panel in front of the right front passenger.
How Does an Air Bag Restrain?
In moderate to severe frontal or near-frontal collisions,
even belted occupants can contact the steering wheel or
the instrument panel. Air bags supplement the
protection provided by safety belts. Air bags distribute
the force of the impact more evenly over the occupant’s
upper body, stopping the occupant more gradually.But air bags would not help you in many types of
collisions, including rollovers, rear impacts and many
side impacts, primarily because an occupant’s motion is
not toward those air bags. Air bags should never be
regarded as anything more than a supplement to safety
belts, and then only in moderate to severe frontal or
near-frontal collisions.
What Will You See After an Air Bag
Inflates?
After an air bag inflates, it quickly deflates, so quickly
that some people may not even realize the air bag
inflated. Some components of the air bag module–the
steering wheel hub for the driver’s air bag, or the
instrument panel for the right front passenger’s
bag–will be hot for a short time. The parts of the bag
that come into contact with you may be warm, but
not too hot to touch. There will be some smoke and dust
coming from the vents in the deflated air bags.
Air bag inflation doesn’t prevent the driver from seeing
or being able to steer the vehicle, nor does it stop
people from leaving the vehicle.
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2003 - Sierra Denali

{CAUTION:
When an air bag inflates, there is dust in the
air. This dust could cause breathing problems
for people with a history of asthma or other
breathing trouble. To avoid this, everyone in
the vehicle should get out as soon as it is safe
to do so. If you have breathing problems but
can’t get out of the vehicle after an air bag
inflates, then get fresh air by opening a
window or a door. If you experience breathing
problems following an air bag deployment, you
should seek medical attention.
In many crashes severe enough to inflate the air bag,
windshields are broken by vehicle deformation.
Additional windshield breakage may also occur from the
right front passenger air bag.
•Air bags are designed to inflate only once. After
they inflate, you’ll need some new parts for your
air bag system. If you don’t get them, the air
bag system won’t be there to help protect you in
another crash. A new system will include air
bag modules and possibly other parts. The service
manual for your vehicle covers the need to
replace other parts.
•Your vehicle is equipped with electronic frontal
sensors which help the sensing system distinguish
between a moderate and a more severe frontal
impact. Your vehicle is also equipped with a crash
sensing and diagnostic module, which records
information about the frontal air bag system. The
module records information about the readiness of
the system and when the system commands
are bag inflation. It records the status of the driver’s
safety belt usage in a crash in which the air bag
deploys or a crash in which the air bag nearly
deploys. The module also records speed, engine
RPM, brake and throttle data.
•Let only qualified technicians work on your air bag
systems. Improper service can mean that an air
bag system won’t work properly. See your dealer for
service.
Notice:If you damage the covering for the driver’s
or the right front passenger’s air bag, the bag
may not work properly. You may have to replace the
air bag module in the steering wheel or both the
air bag module and the instrument panel for
the right front passenger’s air bag. Do not open or
break the air bag coverings.
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2003 - Sierra Denali

Keys...............................................................2-2
Remote Keyless Entry System.........................2-3
Remote Keyless Entry System Operation...........2-4
Doors and Locks.............................................2-6
Door Locks....................................................2-6
Power Door Locks..........................................2-7
Programmable Automatic
Door Locks................................................2-7
Rear Doors...................................................2-9
Tailgate.......................................................2-10
Windows........................................................2-11
Power Windows............................................2-12
Swing-Out Windows......................................2-12
Sun Visors...................................................2-13
Theft-Deterrent Systems..................................2-13
Content Theft-Deterrent.................................2-13
Passlock
®....................................................2-15
Starting and Operating Your Vehicle................2-15
New Vehicle Break-In....................................2-15
Ignition Positions
..........................................2-16
Starting Your Engine
.....................................2-17
Engine Coolant Heater
..................................2-18
Automatic Transmission Operation
...................2-19
All-Wheel Drive
............................................2-21
Parking Brake
..............................................2-22Shifting Into Park (P).....................................2-23
Shifting Out of Park (P).................................2-25
Parking Over Things That Burn.......................2-26
Engine Exhaust............................................2-26
Running Your Engine While You Are Parked. . . .2-27
Mirrors...........................................................2-28
Automatic Dimming Rearview Mirror with
OnStar
®, Compass and Temperature
Display....................................................2-28
Outside Power Mirrors...................................2-31
Outside Power Foldaway Mirrors.....................2-31
Outside Automatic Dimming Mirror..................2-32
Outside Curb View Assist Mirrors....................2-32
Outside Convex Mirror...................................2-32
Outside Heated Mirrors..................................2-32
OnStar
®System.............................................2-33
HomeLink®Transmitter...................................2-35
Programming the HomeLink®Transmitter.........2-35
Storage Areas................................................2-39
Glove Box...................................................2-39
Cupholder(s)................................................2-39
Center Console Storage Area.........................2-39
Tonneau Cover............................................2-39
Vehicle Personalization...................................2-41
Memory Seat...............................................2-41
Section 2 Features and Controls
2-1
2003 - Sierra Denali

Automatic Transmission Operation
Your vehicle is equipped with an automatic transmission
that features an electronic shift position indicator
located within the instrument panel cluster. This display
is powered anytime the shift lever is capable of being
moved out of PARK (P). SeeFuses and Circuit Breakers
on page 5-91.
There are several different positions for your shift lever.
PARK (P):This position locks your wheels. It’s the
best position to use when you start your engine because
your vehicle can’t move easily.
{CAUTION:
It is dangerous to get out of your vehicle if the
shift lever is not fully in PARK (P) with the
parking brakefirmly set. Your vehicle can roll.
Don’t 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.
CAUTION: (Continued)
CAUTION: (Continued)
To be sure your vehicle won’t move, even
when you’re on fairly level ground, always set
your parking brake and move the shift lever to
PARK (P). See“Shifting Into Park (P)”in the
Index. If you’re pulling a trailer, see“Towing a
Trailer”in the Index.
REVERSE (R):Use this gear to back up.
Notice:Shifting to REVERSE (R) while your vehicle
is moving forward could damage your transmission.
Shift to REVERSE (R) only after your vehicle is
stopped.
To rock your vehicle back and forth to get out of snow,
ice or sand without damaging your transmission,
seeIf You Are Stuck: In Sand, Mud, Ice or Snow on
page 4-44.
NEUTRAL (N):In this position, your engine doesn’t
connect with the wheels. To restart when you’re already
moving, use NEUTRAL (N) only. Also, use
NEUTRAL (N) when your vehicle is being towed.
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2003 - Sierra Denali