
The 2003 GMC  Sierra Denali Owner  Manual a 
Seats  and  Restraint  Systems ........................... 1-1 
Front  Seats ............................................... 1-2 
Rear  Seats 
............................................... 1-7 
Safety  Belts 
.............................................. 1-8 
Child  Restraints 
....................................... 1-30 
Air  Bag  Systems 
...................................... 1-57 
Restraint  System  Check 
............................ 1-73 
Features  and  Controls 
..................................... 2-1 
Keys 
........................................................ 2-2 
Doors  and  Locks 
....................................... 2-6 
Windows 
................................................. 2-1 0 
Theft-Deterrent  Systems ............................ 2-1 3 
Starting  and Operating Your Vehicle ........... 2-15 
Mirrors 
.................................................... 2-28 
Onstar@  System 
...................................... 2-33 
HomeLink@  Transmitter 
............................. 2-35 
Storage  Areas 
......................................... 2-39 
Instrument  Panel 
............................................. 3-1 
Vehicle 
Personalization 
............................. 2-42 
Instrument  Panel  Overview 
.......................... 3-2 
Climate  Controls 
...................................... 3-1 8 
Warning  Lights,  Gages  and  Indicators 
......... 3-24 
Driver Information Center  (DIC) 
.................. 3-43 
Audio  System(s) 
....................................... 3-61  Driving  Your  Vehicle 
....................................... 4-1 
Your 
Driving, the  Road, and Your  Vehicle ..... 4-2 
Towing 
................................................... 4-45 
Service  and Appearance Care 
.......................... 5-1 
Service 
..................................................... 5-3 
Fuel 
......................................................... 5-5 
Checking  Things  Under  the  Hood 
............................................. 5-10 
All-Wheel  Drive 
........................................ 5-49 
Rear  Axle 
............................................... 5-50 
Front Axle 
............................................... 5-51 
Bulb  Replacement 
.................................... 5-52 
Windshield  Wiper Blade Replacement 
......... 5-60 
Tires 
...................................................... 5-61 
Appearance  Care 
..................................... 5-86 
Vehicle  Identification 
................................. 5-94 
Electrical  System 
...................................... 5-95 
Capacities  and Specifications 
................... 5-1 04 
Normal  Maintenance  Replacement  Parts 
.... 5-1 05 
Maintenance  Schedule 
..................................... 6-1 
Maintenance  Schedule 
................................ 6-2 
Customer Assistance  Information 
.................... 7-1 
Customer  Assistance  Information 
.................. 7-2 
Reporting Safety  Defects 
............................ 7-9 
Index 
................................................................. 1  

Your vehicle has a  light 
that comes  on as 
a 
reminder  to  buckle up. See 
Safety Belt Reminder 
Light 
on page 3-26. 
In  most  states  and  in all  Canadian provinces,  the  law 
says  to  wear  safety  belts.  Here’s why: 
They work. 
You  never  know if you’ll  be  in a crash. If you  do  have a 
crash,  you  don’t  know 
if it  will  be a bad  one. 
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 
OP 
wheels. 
1-9  

r 
There is an air bag 
readiness light  on the 
instrument panel cluster, 
which  shows  the air 
bag 
symbol. 
Where  Are  the Air Bags? 
The  system  checks  the  air  bag  electrical system for 
malfunctions.  The  light tells you 
if there  is  an electrical 
problem.  See 
Air  Bag  Readiness  Light on page 3-27 
for  more information. 
The driver’s air  bag is in the  middle  of the steering 
wheel. 
1-59  

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. 
The  right  front passenger’s air  bag  is in the  instrument 
panel 
on the passenger’s  side. 
1-60  

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. 
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. 
1-61  

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. 
1-62  

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. 
1-63  

Section 2 Features  and  Controls 
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 
Rear  Doors 
................................................... 2-8 
Tailgate 
........................................................ 2-8 
Windows 
........................................................ 2-10 
Power  Windows 
............................................ 2-11 
Swing-Out  Windows 
...................................... 2-11 
Sun  Visors 
................................................... 2-12 
Theft-Deterrent  Systems 
.................................. 2.13 
Content  Theft-Deterrent 
................................. 2.13 
Passlock@ 
.................................................... 2.14 
Starting  and  Operating  Your  Vehicle 
................ 2.15 
New  Vehicle  Break-In 
.................................... 2.15 
Ignition Positions 
.......................................... 2.15 
Starting  Your  Engine 
..................................... 2.16 
Engine  Coolant  Heater 
.................................. 2.17 
Automatic  Transmission Operation 
................... 2.18 
All-Wheel  Drive 
............................................ 2-21 
Parking  Brake 
.............................................. 2-22 
Shifting 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 
OnStap,  Compass  and  Temperature 
Display 
.................................................... 2-28 
Outside  Power Mirrors 
................................... 2-31 
Outside  Power  Foldaway  Mirrors 
..................... 2-31 
Outside Automatic  Dimming Mirror 
.................. 2-31 
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 
................................... 2-42 
Memory  Seat 
............................................... 2-42 
2- 1