
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  

Here’s how to avoid setting off the alarm by  accident: 
If  you  don’t  want to activate the theft-deterrent 
system,  the vehicle should  be locked with  the  door 
key  after  the doors are closed. 
Always  unlock a  door with a key,  or use  the remote 
keyless entry transmitter. Unlocking  a  door  any 
other  way will set 
off the  alarm if the  system 
has  been  armed. 
If you  set off the alarm  by accident, unlock  any  door 
with  the key.  You  can  also turn 
off the alarm by pressing 
UNLOCK  on the  remote  keyless entry transmitter or 
by  placing  the  key  in  the ignition  and turning it  to 
START. 
Testing the Alarm 
The  alarm  can be tested  by following these steps: 
1. From  inside the vehicle, lower the driver’s  window 
and  open  the  driver’s door. 
2. Activate the  system by locking  the doors with  the 
power  door  lock  switch while the door is open, or 
with the  remote keyless entry transmitter. 
3. Get out of the  vehicle, close  the door  and  wait for 
the  security  message 
to go  out. 
4. Then reach  in through  the window,  unlock the door 
with  the  manual  door  lock and open the door. This 
should  set 
off the  alarm.  If  the 
alarm  does not sound  and  the  headlamps  do  not 
flash,  you  may  have  the  feature  turned 
off. See DIC 
Operation and Displays on page 3-43 for  more 
information. 
Passlock@ 
Your  vehicle is  equipped  with  the 
Passlock@  theft-deterrent  system. 
Passlock@  is a passive theft-deterrent  system. 
Passlock@  enables 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 flashes, 
wait  until the light  stops flashing 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@  system  is 
not  working properly  and  must  be serviced by  your 
dealer.  Your vehicle is  not protected by  Passlock@  at this 
time.  You  may  also  want  to  check  the fuse  (see 
Fuses  and Circuit  Breakers on page 5-95.) See  your 
dealer  for service. 
In  an  emergency,  call the  GM  Roadside  Assistance 
Center.  See 
Roadside  Assistance  Program on page 7-5 
under  Customer  Assistance  Information. 
2-1 4  

When starting  your engine  in very cold  weather (below 
0°F or -18"C), do this: 
Engine  Coolant  Heater 
1. With  your  foot off the  accelerator  pedal, turn the 
ignition key  to START  and  hold it there up to 
15 seconds.  When  the engine starts, let  go  of 
the  key. 
2. If  your  engine still  won't  start  (or  starts  but then 
stops),  it could  be flooded with too  much gasoline. 
Try pushing  your accelerator pedal  all the  way  to the 
floor  and  holding 
it there as  you  hold the key  in 
START  for  about  three seconds. When the engine 
starts,  let go  of  the key  and  accelerator.  If the 
vehicle  starts  briefly but then stops  again, do the 
same  thing,  but this  time  keep  the  pedal down 
for  five  or  six  seconds.  This clears the extra 
gasoline  from the engine. 
Notice: Your  engine  is designed  to  work  with  the 
electronics  in your  vehicle. 
If you  add  electrical 
parts  or accessories,  you  could  change  the way  the 
engine  operates.  Before  adding electrical  equipment, 
check  with  your  dealer. 
If you  don't,  your engine 
might  not  perform  properly.  In 
very  cold weather, 
0°F (-18°C) or colder, 
the  engine coolant heater 
can  help. You'll  get 
easier starting and better 
fuel  economy  during 
engine  warm-up.  Usually, 
the coolant heater 
should  be  plugged  in a 
minimum  of four hours 
prior to  starting your 
vehicle. 
At  temperatures  above 
32°F (OOC), use of the coolant 
heater is  not required. 
2-1 7  

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. 
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 occasionally. 
If  you  manually  select  SECOND 
(2), 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  shift  lever  is put  in  FIRST (1) while  the  vehicle 
is  moving  forward,  the transmission  won’t  shift  into  first 
gear  until the vehicle  is going  slowly  enough. 
Notice: If your  rear  wheels  won’t  turn,  don’t  try  to 
drive.  This might  happen 
if you  were  stuck  in 
very  deep  sand  or  mud  or  were  up  against  a  solid 
object.  You could  damage  your  transmission. 
Also,  if you  stop  when  going  uphill, don’t  hold  your 
vehicle  there with  only  the  accelerator  pedal. 
This could overheat  and  damage the transmission. 
Use  your  brakes  or  shift  into  PARK  (P)  to hold 
your  vehicle in position  on  a  hill. 
On  cold  days,  approximately 
32°F (OOC)  or colder,  your 
transmission is designed  to  shift  differently  until  the 
engine reaches normal  operating  temperature.  This  is 
intended to  improve  heater  performance. 
2-20  

Section 3 Instrument  Panel 
I~s~Pu~~~IP Panel OWWV~~W ............................... 3.2 
Hazard  Warning  Flashers 
................................ 3.3 
Other  Warning  Devices ................................... 3.4 
Horn 
............................................................. 3.4 
Tilt  Wheel 
..................................................... 3.4 
Turn  SignaVMultifunction  Lever 
......................... 3.5 
Exterior  Lamps 
............................................. 3.11 
Interior  Lamps 
.............................................. 3.15 
Accessory  Power  Outlets 
............................... 3.16 
Ashtrays  and  Cigarette  Lighter 
........................ 3.17 
Climate  Controls 
............................................ 3.18 
Dual  Automatic  Climate  Control System 
........... 3.18 
Warning  Lights,  Gages  and Indicators 
............. 3.24 
Instrument  Panel  Cluster 
................................ 3.25 
Speedometer  and  Odometer 
........................... 3.26 
Tachometer 
................................................ -3-26 
Safety  Belt  Reminder  Light 
............................. 3.26 
Air  Bag  Readiness  Light 
................................ 3-27 
Passenger  Air  Bag  Status  Indicator 
................. 3.30 
Battery  Warning  Light 
.................................... 3.33 
Brake  System  Warning  Light 
.......................... 3.34 
Anti-Lock  Brake  System  Warning  Light 
............. 3.35 
Air 
Bag 
Off Light .......................................... 3-28 
Voltmeter  Gage 
............................................ 3-33 
Engine  Coolant  Temperature  Gage 
..... ..... 3.36  Transmission Temperature 
Gage 
..................... 3.36 
Malfunction Indicator  Lamp 
............................. 3.38 
Oil  Pressure  Gage 
........................................ 3-40 
Cruise  Control  Light 
...................................... 3.41 
Tow/Haul  Mode  Light 
.................................... 3-41 
Fuel  Gage 
................................................... 3.42 
Driver  Information  Center  (DIC) 
....................... 3.43 
DIC  Operation and  Displays 
........................... 3.43 
DIC  Warnings  and  Messages 
......................... 3.53 
Audio  System(s) 
............................................. 3.61 
Setting  the Time 
...................... .......... 3.6 1 
Radio  with  Cassette  and  CD ..... .............. 3.62 
Rear  Seat  Audio  (RSA) 
............................. 3.76 
CD  Changer 
................................................ 3-78 
Theft-Deterrent  Feature 
................................. -3-81 
Audio  Steering  Wheel Controls 
....................... 3.81 
Understanding  Radio  Reception 
...................... 3-82 
Care  of Your  Cassette  Tape  Player 
................ -3-83 
Care  of  Your  CDs 
......................................... 3.84 
Care  of  Your  CD  Player 
................................ 3.84 
Fixed  Mast  Antenna 
...................................... 3.84 
XMTM Satellite  Radio  Antenna  System 
............. 3.84 
DAB  Radio  Antenna  System 
........................... 3.84 
Low  Fuel  Warning  Light 
................................. 3-42  

Instrument  Panel  Cluster 
Your instrument panel cluster  is designed  to let  you  know  at  a  glance how your vehicle is running. You’ll  know  how 
fast  you’re  going, about  how  much  fuel you  have  and many  other things  you’ll need to know  to drive safely and 
economically. 
United States version  shown,  Canada  similar 
3-25  

Malfunction Indicator Lamp 
Check Engine  Light 
Your vehicle is equipped 
with  a  computer  which 
monitors operation  of the 
fuel,  ignition  and emission 
control systems. 
I I 
This  system  is called  OBD I1 (On-Board 
Diagnostics-Second Generation)  and is intended to 
assure  that emissions are  at acceptable levels  for the 
life  of the  vehicle,  helping to  produce a cleaner 
environment.  The  Check  Engine  light comes  on  to 
indicate that there  is a  problem  and  service is required. 
Malfunctions often will  be indicated by the  system 
before any  problem is apparent. This  may prevent  more 
serious  damage  to your  vehicle. This  system is also 
designed  to assist your service technician  in correctly 
diagnosing  any malfunction. 
Notice: If  you  keep  driving  your  vehicle  with  this 
light on, after  a  while,  your  emission  controls 
may  not  work  as  well, your  fuel  economy  may  not 
be  as  good  and  your  engine  may  not 
run as 
smoothly.  This  could  lead  to  costly  repairs  that  may  not  be  covered  by  your  warranty. 
Notice: Modifications  made  to  the  engine, 
transmission,  exhaust,  intake  or  fuel  system  of  your 
vehicle  or  the  replacement  of  the  original  tires 
with  other  than  those  of the  same  Tire  Performance 
Criteria  (TPC) can  affect  your  vehicle’s  emission 
controls  and  may  cause  this  light  to  come  on. 
Modifications  to  these  systems  could  lead  to  costly 
repairs  not  covered  by your  warranty.  This  may 
also  result  in  a  failure  to 
pass a  required  Emission 
Inspection/Maintenance  test. 
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  doesn’t  come  on,  have  it 
repaired. This  light  will  also  come  on  during  a 
malfunction  in one  of  two  ways: 
Light  Flashing - A misfire condition  has  been 
detected. 
A misfire  increases  vehicle  emissions 
and  may  damage  the  emission  control system  on 
your  vehicle.  Dealer  or qualified  service  center 
diagnosis  and  service  may  be  required. 
Light  On  Steady - An emission  control  system 
malfunction  has been  detected  on  your  vehicle. 
Dealer  or qualified service center  diagnosis 
and  service  may  be  required. 
3-38  

If the  Light is Flashing 
The  following  may  prevent  more  serious damage  to 
your  vehicle: 
Reducing  vehicle  speed. 
Avoiding  hard accelerations. 
0 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 flashing and remains  on steady,  see  “If 
the  Light 
Is On  Steady”  following. 
If  the  light continues to flash,  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 
“If 
the  Light Is On Steady”  following. If the  light  is still 
flashing,  follow  the previous steps,  and drive the vehicle 
to  your  dealer  or  qualified service center for  service. 
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 
Fi//ing 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. 
Have you recently  changed  brands of fuel? 
If 
so, be  sure  to fuel your vehicle with quality fuel.  See 
Gasoline Octane on page 5-5. Poor  fuel quality will 
cause  your  engine not to run 
as efficiently  as designed. 
You  may  notice this  as  stalling  after start-up, stalling 
when  you  put the  vehicle into  gear, misfiring, hesitation 
on  acceleration or stumbling  on acceleration.  (These 
conditions  may go away  once  the  engine is warmed  up.) 
This will  be detected  by the  system  and  cause  the 
light to turn  on. 
If  you  experience  one  or  more  of these conditions, 
change  the fuel  brand you use.  It will  require at  least 
one  full tank  of the  proper fuel to turn the light  off. 
If none of the  above  steps have  made  the  light turn off, 
have your dealer  or qualified service center  check 
the vehicle.  Your dealer  has the proper test  equipment 
and  diagnostic tools  to 
fix any mechanical  or electrical 
problems  that may  have  developed. 
3-39