
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  

Servicing Your Air Bag-Equipped 
Vehicle 
Air  bags  affect  how  your vehicle should  be serviced. 
There  are parts  of the  air bag  system  in several places 
around  your  vehicle. You  don’t  want  the system  to 
inflate while  someone 
is working on  your vehicle.  Your 
dealer and the service  manual  have information 
about  servicing your vehicle  and  the air bag  system.  To 
purchase  a  service manual,  see 
Service Publications 
Order’  Information 
on page 7- 10. 
E 
For  up  to 1 minute  after  the il tiol :ey is 
turned off and  the  battery  is  disconnected,  an 
air  bag  can 
still inflate  during  improper 
service.  You can  be  injured  if  you  are close  to 
an  air  bag  when 
it inflates.  Avoid  yellow 
connectors.  They  are  probably  part  of  the  air  bag  system.  Be  sure  to  follow  proper  service 
procedures,  and  make  sure  the  person  performing  work  for  you 
is qualified  to  do so. 
Adding  Equipment  to  Your Air 
Bag-Equipped  Vehicle 
Q: Is  there  anything I might  add  to  the  front  or 
sides  of  the  vehicle  that  could  keep the  air 
bags  from  working  properly? 
frame,  bumper  system,  front end or side  sheet 
metal  or  height,  they  may  keep  the  air  bag  system 
from working  properly.  Also,  the  air  bag  system 
may  not work  properly 
if you  relocate  any  of the  air 
bag  sensors. 
If you  have  any  questions  about 
this,  you  should contact  Customer  Assistance 
before  you modify  your  vehicle.  The  phone  numbers 
and  addresses  for  Customer  Assistance  are  in 
Step  Two  of the  Customer  Satisfaction  Procedure 
in  this  manual.  See 
Customer  Satisfaction 
Procedure 
on page 7-2. 
A: Yes.  If  you  add  things  that  change  your  vehicle’s 
The air bag  system  does  not need  regular maintenance. 
1 -72  

Restraint  System  Check 
Checking Your Restraint  Systems  Replacing  Restraint  System 
Parts 
After  a  Crash 
Now  and  then, make  sure the safety belt reminder light 
and  all  your  belts, buckles,  latch plates, retractors 
and  anchorages  are working properly.  Look  for  any other 
loose  or  damaged  safety belt system parts. If  you  see 
anything  that might  keep  a  safety  belt system  from doing 
its  job,  have  it repaired. 
Torn  or  frayed safety belts  may not protect  you in a 
crash.  They  can  rip apart  under  impact forces. 
If a belt 
is torn  or  frayed,  get  a new  one  right away. 
Also  look for  any  opened  or  broken air bag covers, and 
have  them  repaired or replaced. (The air bag  system 
does  not  need  regular  maintenance.) 
A crash can damage the  restraint  systems in 
your  vehicle. 
A damaged restraint  system  may 
not properly protect the  person using it, 
resulting in serious injury  or even death in a 
crash. 
To help  make  sure  your  restraint 
systems  are  working properly after a crash, 
have them inspected and  any necessary 
replacements made  as soon 
as possible. 
If you’ve  had a crash,  do you  need  new  belts or  LATCH 
system  parts? 
After  a  very  minor collision, nothing  may be necessary. 
But 
if the  belts  were stretched, as they  would be if 
worn during  a  more  severe crash,  then  you need 
new  parts. 
1-73  

See Driver Information  Center (DIC) on  page 3-43 for 
further  information. 
If the transmission fluid reaches temperatures  of 
approximately  275°F 
(1 35°C)  or greater,  the Driver 
Information  Center  wiil display a 
TRANS HOT IDLE 
ENG warning  message.  Pull the vehicle off the  roadway 
when  it 
is safe  to  do so. Set the parking brake, place 
the  transmission  in PARK 
(P) and  allow the engine 
to  idle until the transmission temperature falls  below 
260°F (1 27°C). If the transmission continues to operate 
above 
265°F (13O"C),  contact your nearest dealer  or 
the 
GM Roadside  Assistance Center.  See Roadside 
Assistance  Program 
on page 7-5. 
Notices If you  keep  driving your vehicle with the 
transmission  temperature  gage above the normal 
operating  range,  you  can  damage the transmission. 
This  could  lead  to  costly  repairs that may not be 
covered  under  your  warranty.  The 
following situations  can cause  the transmission  to 
operate at  higher temperatures: 
0 Towing  a trailer 
0 Hot  outside air temperatures 
0 Hauling  a large  or  heavy  load 
0 Low transmission fluid  level 
High transmission fluid  level 
0 Restricted air flow to the  radiator and  the auxiliary 
transmission oil cooler 
(if equipped). 
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 
6-5 for the  proper transmission  maintenance 
intervals. 
3-37  

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  

Emissions Inspection and  Maintenance 
Programs 
Some state/provincial and local  governments have or 
may begin programs to  inspect the emission control 
equipment on  your vehicle.  Failure to  pass this 
inspection could prevent you from getting a vehicle 
registration. 
Here are  some things you  need  to  know to help  your 
vehicle pass  an inspection: 
Your  vehicle  will  not  pass this  inspection 
if the Check 
Engine light is  on or not  working properly. 
Your  vehicle  will  not  pass this  inspection 
if the OBD 
(on-board  diagnostic)  system determines  that critical 
emission control systems have  not been completely 
diagnosed by the  system. The vehicle  would be 
considered  not ready for  inspection. This can happen 
if 
you  have  recently  replaced  your battery  or if your 
battery has run down. The  diagnostic  system is 
designed to  evaluate critical emission control  systems 
during normal  driving. This  may take several  days 
of  routine  driving. 
If you  have done this and your vehicle 
still does  not pass the  inspection  for  lack of 
OBD 
system readiness,  see your dealer  or qualified service 
center to  prepare the vehicle  for  inspection. 
Oil Pressure  Gage 
I I 
United  States  Canada 
The oil pressure  gage  shows the engine  oil  pressure  in 
psi (pounds per  square  inch)  when  the  engine  is 
running.  Canadian  vehicles  indicate  pressure  in  kPa 
(kilopascals). 
Oil  pressure  may  vary  with  engine  speed,  outside 
temperature and oil  viscosity,  but  readings  above  the 
low pressure zone  indicate  the  normal  operating  range. 
3-40  

Fuel Information Button 
Use the fuel information button to scroll through the 
range,  average  fuel economy,  instant fuel  economy and 
the  GM 
Oil Life  SystemTM. 
If your vehicle  is not  equipped  with the DIC  steering 
wheel  control buttons  you will not  be able  to display the 
fuel  information. 
Fuel Range 
Press  the fuel  information button until  RANGE  appears 
to  display  the remaining distance  you can  drive 
without refueling. It’s  based  on fuel economy  and  the 
fuel  remaining in the tank.  The display will  show 
LOW if 
the fuel  level  is low. 
The fuel  economy  data used  to determine  fuel range  is 
an  average  of recent driving conditions.  As your 
driving conditions change, this data  is gradually  updated. 
Fuel range cannot  be reset. 
Average  Fuel Economy 
Press  the  fuel information button until  AVG  appears in 
the display.  Average  fuel economy  is how  many 
miles per gallon  your vehicle  is getting  based  on  current 
and  past driving conditions. 
Press  and hold  the select button while  AVG.ECON is 
displayed  to reset  the average  fuel economy.  Average 
fuel  economy  will then 
be calculated starting  from 
that  point. 
If the  average  fuel economy  is not reset, it 
will  be continually  updated  each  time you drive. 
Instant Fuel  Economy 
Press the fuel  information button until  INST  appears in 
the  display. Instant fuel  economy is how  many  miles 
per gallon  your vehicle  is at  the particular  moment 
in  time.  The instant  fuel  economy  cannot  be  reset. 
GM Oil Life SystemTM 
Press the fuel  information button until  ENGINE OIL LIFE 
appears  in  the display.  The  GM 
Oil Life  SystemTM 
shows  an  estimate of the  oil’s  remaining  useful  life.  It 
will  show 
100% when  the  system  is reset  after  an 
oil  change.  It will alert  you 
to change  your  oil on  a 
schedule consistent  with  your driving conditions. 
Always  reset the  engine oil life after  and  oil  change. 
To 
reset the Oil  Life  System  press and hold  the  select 
button while  ENGINE 
OIL LIFE  is  displayed. 
The  DIC does  not  replace  the  need to maintain  your 
vehicle as  recommended  in the  Maintenance  Schedule 
in  this manual.  Also,  the oil change  reminder  will not 
detect dusty conditions  or  engine  malfunctions  that  may 
affect the  oil.  Also, the oil change  reminder  does  not 
measure  how  much 
oil you  have  in your  engine. So, be 
sure  to check  your oil level  often.  See 
Engine Oil on 
page 5- 13. 
3-46  

TRANSMISSION HOT 
If the  transmission  fluid  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  fluid  temperature 
returns  to normal,  the  display  will  turn 
off and  the 
transmission  shifting  patterns  will  return 
to normal. 
Nofice: If you  keep  driving your  vehicle  with the 
transmission 
TRANS FLUID HOT message 
displayed,  you  can  damage the transmission. 
This 
could  lead to costly  repairs  that  may  not be covered 
under  your  warranty.  The 
following  situations  can  cause the transmission to 
operate  at  higher  temperatures: 
Towing  a  trailer 
Hot  outside  air temperatures 
0 Hauling  a  large  or  heavy load 
Low  transmission  fluid  level 
High  transmission  fluid  level 
transmission  oil  cooler. 
0 Restricted  air  flow  to  the  radiator  and the auxiliary 
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 6-5 for  the  proper  transmission  maintenance 
intervals. 
3-59