
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  

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  

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  

If the  water  isn’t  too deep,  drive slowly through  it.  At 
faster  speeds,  water  splashes  on your  ignition system 
and your vehicle can  stall. Stalling can also  occur 
if you 
get your tailpipe under  water.  And, as long  as your 
tailpipe  is under  water,  you’ll  never be able to start  your 
engine.  When you go through  water, remember that 
when  your brakes get  wet,  it may take you  longer 
+- stop. 
,,jving  thr,,gh  rushing water can  be 
dangerous.  Deep  water can sweep  your  vehicle 
downstream  and  you  and  your  passengers 
could  drown.  If it’s  only  shallow  water, it can 
still  wash  away  the ground  from under  your 
tires,  and  you  could  lose  traction and roll the 
water. 
~ vehicle  over.  Don’t  drive through rushing 
I 
After Off-Road Driving 
Remove any  brush or  debris  that has collected  on the 
underbody,  chassis or under  the  hood.  These 
accumulations can  be  a fire  hazard. 
After  operation 
in mud or  sand,  have  the  brake  linings 
cleaned and checked.  These  substances  can  cause 
glazing and uneven  braking.  Check  the  body  structure, 
steering,  suspension,  wheels,  tires  and exhaust 
system  for damage.  Also,  check  the fuel  lines  and 
cooling system for  any  leakage. 
Your  vehicle will  require  more  frequent  service  due 
to 
off-road use.  Refer  to the  Maintenance  Schedule 
for  additional  information. 
See 
Driving  in  Rain  and on Wet Roads on page 4-30 for 
more  information  on driving through  water. 
4-28  

Towing a Trailer 
If you  don’t  ,se the correct eq-., ...__. t and 
drive  properly,  you  can  lose  control  when  you 
pull  a  trailer.  For  example, 
if the  trailer is too 
heavy,  the  brakes  may not  work  well 
-- or  even 
at  all.  You  and  your  passengers  could  be 
seriously  injured. 
Pull a  trailer  only  if  you  have 
followed  all  the  steps  in  this  section. 
Ask your 
dealer  for  advice  and  information  about  towing 
a  trailer  with  your  vehicle. 
Notice: Pulling  a  trailer  improperly  can  damage 
your  vehicle  and  result  in  costly  repairs  not  covered 
by  your  warranty. 
To pull  a  trailer  correctly,  follow 
the  advice  in  this  part, and see your  dealer  for 
important  information  about  towing  a  trailer  with 
your  vehicle.  Additional  rear  axle  maintenance  is  required  for  a  vehicle  used  to  tow  a  trailer.  See 
“Scheduled  Maintenance  Services”  in  the Index. 
To  identify  the vehicle  trailering capacity  of your vehicle, 
you  should read the information  in “Weight  of the 
Trailer”  that  appears  later in this section. 
If yours  was built with trailering options, as  many are, 
it’s  ready  for heavier trailers.  But trailering  is different 
than just  driving  your vehicle  by itself. Trailering  means 
changes  in handling, durability  and fuel  economy. 
Successful, safe trailering takes correct equipment, and  it  has  to be  used  properly. 
That’s the reason for this  part. In it are  many  time-tested, 
important trailering tips  and safety  rules.  Many  of 
these are important  for  your safety and that  of your 
passengers. 
So please read this section carefully before 
you  pull a trailer. 
If You Do  Decide  To Pull A Trailer 
If you  do,  here are  some important points: 
e 
There  are many  different laws, including speed  limit 
restrictions, having  to do  with trailering.  Make sure 
your  rig will  be legal, not only  where  you live 
but also  where you’ll be driving. 
A good  source for 
this  information  can  be state or provincial police. 
Consider  using a  sway  control 
if your trailer  will 
weigh 
5,000 Ibs. (2  270  kg)  or  less.  You  should 
always  use  a  sway  control 
if your trailer will  weigh 
more  than 
5,000 Ibs.  (2  270  kg).  You  can ask  a 
hitch dealer about  sway controls. 
Don’t  tow  a  trailer  at all  during the first 
500 miles 
(800 km)  your  new vehicle is driven.  Your engine, 
axle  or other parts could  be damaged. 
4-5 1  

When You Are  Ready to Leave  After 
Parking  on  a 
Hill 
1. Apply  your  regular  brakes and hold  the pedal  down 
while  you: 
0 start  your  engine, 
shift  into a  gear,  and 
0 release  the  parking brake. 
2. Let  up  on  the  brake  pedal. 
3. Drive slowly  until the trailer  is clear  of the  chocks. 
4. Stop  and  have  someone  pick up  and  store the 
chocks. 
Maintenance  When  Trailer  Towing 
Your vehicle will  need service  more often  when  you’re 
pulling  a trailer.  See the Maintenance  Schedule  for more 
on  this.  Things  that are especially important  in trailer 
operation are automatic transmission  fluid (don’t overfill), 
engine 
oil, axle lubricant, belt, cooling  system and 
brake  system.  Each  of  these  is covered  in  this manual, 
and  the Index will help  you find  them  quickly.  If 
you’re  trailering, it’s  a  good idea to review these sections 
before  you start your trip. 
Check  periodically  to see  that  all hitch nuts and bolts 
are tight. 
4-59  

To replace the engine air cleaner/filter do the following: 
1. Loosen  the  screws  on  the cover of the housing 
and  lift up  the  cover. 
2. Remove  the  air cleaner/filter from  the housing. 
Care  should  be taken 
to dislodge  as little dirt 
as possible. 
3. Clean  the filter sealing surface  and the  housing. 
4. Install the  new engine air cleanedfilter. 
5. Reinstall the cover and tighten the screws.  Refer 
to the  Maintenance  Schedule  to determine  when 
to replace the engine  air cleaner/filter.  See 
Part B: Owner  Checks  and  Services on  page 6-10. 
Operating  the  engine  with  the  air  cleanedfilter 
off can  cause  you  or  others  to  be  burned. The 
air  cleaner  not  only  cleans  the  air, 
it stops 
flame 
if the engine  backfires. If it isn’t  there 
and  the  engine  backfires,  you  could  be  burned.  Don’t  drive  with 
it off, and  be  careful  working 
on  the  engine  with  the  air  cleaner/filter 
off. 
Notice: If  the  air  cleaner/filter  is off, a  backfire 
can  cause  a  damaging  engine  fire.  And, dirt 
can  easily  get  into  your  engine,  which  will  damage 
it. Always  have  the air cleanedfilter  in  place 
when  you’re  driving. 
5-20