2003 GMC SIERRA DENALI engine

22,500 Miles (37 500 km)
0 Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-62 for proper rotation pattern and additional
information.
(See footnote +.)
0 Rotate tires. See Tire Inspection and Rotation on
30,000 Miles (50 000 km)
CI Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-62 for proper rotation pattern and additional
information.
(See footnote +.)
0 Replace fuel filter. An Emission Control Service. (See
0 Rotate tires. See Tire Inspection and Rotation on
footnote
t.)
Control Service.
Ll Replace engine air cleaner filter. An Emission
37,500 Miles (62 500 km)
0 Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle
s
for leaking.
0 Rotate tires. See Tire Inspection and Rotation on
ea1 S
45,000 Miles (75 000 km)
0 Inspect engine air cleaner filter if you are driving in
dusty conditions. Replace filter
if necessary. An
Emission Control Service. (See footnote
t.)
0 Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-62 for proper rotation pattern and additional
information.
(See footnote +.)
CI Rotate tires. See Tire Inspection and Rotation on
50,000 Miles (83 000 km)
0 Change automatic transmission fluid and filter if the
vehicle is mainly driven under one or more of these
conditions:
- In heavy city traffic where the outside
temperature regularly reaches
90°F (32°C) or
higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.
If you do not use your vehicle under any of these
conditions, change the fluid and filter at
100,000 miles
(166
000 km).
page 5-62
for proper rotation pattern and additional
information.
(See footnote +.)
6-7

52,500 Miles (87 500 km)
U Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-62 for proper rotation pattern and additional
information.
(See footnote +.)
il Rotate tires. See Tire Inspection and Rotation on
60,000 Miles (100 000 km)
5
u
0
Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
Rotate tires. See
Tire Inspection and Rotation on
page 5-62
for proper rotation pattern and additional
information.
(See footnote +.)
Replace fuel filter. An Emission Control Service. (See
footnote
t.)
Replace engine air cleaner filter. An Emission
Control Service.
Inspect Evaporative Control System. Check all fuel
and vapor lines and hoses for proper hook-up,
routing and condition. Check that the purge valve
works properly,
if equipped. Replace as needed. An
Emission Control Service. (See footnote
t.)
67,500 Miles (112 500 km)
CI Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-62 for proper rotation pattern and additional
information.
(See footnote +.)
0 Rotate tires. See Tire Inspection and Rotation on
75,000 Miles (125 000 km)
U Inspect engine air cleaner filter if you are driving in
dusty conditions. Replace filter
if necessary. An
Emission Control Service. (See footnote
f.)
0 Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
5 Rotate tires. See Tire Inspection and Rotation on
page 5-62
for proper rotation pattern and additional
information.
(See footnote +.)
82,500 Miles (137 500 km)
0 Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-62 for proper rotation pattern and additional
information.
(See footnote +.)
0 Rotate tires. See Tire Inspection and Rotation on
6-8

90,000 Miles (150 000 km)
0 Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
0 Replace fuel filter. An Emission Control Service. (See
Footnote
t.)
0 Replace engine air cleaner filter. An Emission
Control Service.
0 Rotate tires. See Tire Inspection and Rotation on
page 5-62
for proper rotation pattern and additional
information.
(See footnote +.)
97,500 Miles (162 500 km)
c[I Check readfront axle fluid level and add fluid as
needed. Check constant velocity joints and axle seals
for leaking.
page 5-62 for proper rotation pattern and additional
information.
(See footnote +.)
0 Rotate tires. See Tire Inspection and Rotation on
100,000 Miles (166 000 km)
0 Inspect spark plug wires. An Emission Control
0 Replace spark plugs. An Emission Control Service.
Service.
0 Change automatic
transmission fluid and filter if the
vehicle
is mainly driven under one or more of these
conditions:
- In heavy city traffic where the outside
temperature regularly reaches
90°F (32°C) or
higher.
- In hilly or mountainous terrain.
- When doing frequent trailer towing.
- Uses such as found in taxi, police or delivery
service.
0 If you haven’t used your vehicle under severe service
conditions listed previously and, therefore, haven’t
changed your automatic transmission fluid, change
both the fluid and filter.
0 Inspect Positive Crankcase Ventilation (PCV) valve.
An Emission Control Service.
150,000 Miles (240 000 km)
0 Drain, flush and refill cooling system (or every
60 months since last service, whichever occurs first).
See
Engine Coolant on page 5-24 for what to use.
Inspect hoses. Clean radiator, condenser, pressure
cap and neck. Pressure test the cooling system
and pressure cap.
An Emission Control Service.
0 Inspect engine accessory drive belt. An Emission
Control Service.
6-9

Part B: Owner Checks and Services
Listed in this part are owner checks and services
which should be performed at the intervals specified to
help ensure the safety, dependability and emission
control performance of your vehicle.
Be sure any necessary repairs are completed at once.
Whenever any fluids or lubricants are added to your
vehicle, make sure they are the proper ones, as shown
in Part
D.
At Each Fuel Fill
It is important for you or a service station attendant to
perform these underhood checks at each fuel fill.
Engine Oil Level Check
Check the engine oil level and add the proper oil if
necessary. See Engine Oil on page 5-13 for further
details.
Engine Coolant Level Check Windshield Washer Fluid Level Check
Check
the windshield washer fluid level in the windshield
washer tank and add the proper fluid
if necessary.
See
Windshield Washer Fluid on page 5-38 for further
details.
At Least Once a Month
Tire Inflation Check
Make sure tries are inflated to the correct pressures.
Don’t forget to check your spare tire. See
Tires on
page 5-61
for further details.
Cassette Tape Player Service
Clean cassette tape player. Cleaning should be done
every
50 hours of tape play. See Audio System(s)
on page 3-61
for further details.
Check the engine coolant level and add
DEX-COOL@
coolant mixture if necessary. See Engine Coolant
on page
5-24 for further details.
6-1 0

Starter Switch Check Automatic Transmission Shift Lock
Contr-l System Check
When you are doing this check, the vehicle
could move suddenly.
If it does, you or others
could be injured. Follow the steps below.
1
1.
2.
3.
Before you start, be sure you have enough room
around the vehicle.
Firmly apply both the parking brake and the regular
brake. See
Parking Brake on page 2-22 if
necessary.
Do not use the accelerator pedal, and be ready to
turn off the engine immediately
if it starts.
Try
to start the engine in each gear. The starter
should work only in PARK (P) or NEUTRAL
(N).
If the starter works in any other position, your
vehicle needs service.
I
_/hen you are doing _.. check, tl vel le
could move suddenly.
If it does, you or others
could be injured.
Follow the steps below.
I
1. Before you start, be sure you have enough room
around the vehicle. It should be parked on a level
surface.
2. Firmly apply the parking brake. See Parking Brake
on page 2-22 if necessary.
Be ready
to apply the regular brake immediately if
the vehicle begins to move.
3. With the engine off, turn the key to the RUN
position, but don’t start the engine. Without applying
the regular brake, try
to move the shift lever out
of PARK (P) with normal effort.
If the shift lever
moves out of PARK (P), your vehicle needs service.
6-1 2

Ignition Transmission Lock Check
While parked, and with the parking brake set, try to turn
the ignition key to LOCK in each shift lever position.
* The key should turn to LOCK only when the
The key should come out only in LOCK.
shift lever
is in PARK (P).
Parking Brake and Automatic
Transmission Park (P) Mechanism
A. le1 , ..
When you are doing this check, your vehicle
could begin to move. You or others could be
injured and property could be damaged. Make
sure there
is room in front of your vehicle in
case it begins to roll. Be ready to apply the
regular brake at once should the vehicle begin
to move. Park on a
fairly steep hill, with the vehicle facing
downhill. Keeping your foot on the regular brake, set the
parking brake.
@ To check the parking brake’s holding ability: With
the engine running and transmission in
NEUTRAL
(N), slowly remove foot pressure from the regular
brake pedal.
Do this until the vehicle is held by the
parking brake only.
ability: With the engine running, shift to PARK (P).
Then release the parking brake followed by the
regular brake.
To check the PARK (P) mechanism’s holding
Underbody Flushing Service
At least every spring, use plain water to flush any
corrosive materials from the underbody. Take care to
clean thoroughly any areas where mud and other debris
can collect.
6-1 3

Part C: Periodic Maintenance
Inspections
Listed in this part are inspections and services which
should be performed at least twice a year (for instance,
each spring and fall).
You should let your dealer’s
service department or other qualified service center do
these jobs. Make sure any necessary repairs are
completed at once.
Proper procedures to perform these services may be
found in a service manual. See
Service Publications
Ordering lnformation on page
7- 10.
Steering and Suspension Inspection
Inspect the front and rear suspension and steering
system for damaged, loose or missing parts, signs of
wear or lack of lubrication. Inspect the power steering
lines and hoses for proper hook-up, binding, leaks,
cracks, chafing, etc.
Exhaust System Inspection
Inspect the complete exhaust system. Inspect the body
near the exhaust system. Look for broken, damaged,
missing or out-of-position parts as well as open seams,
holes, loose connections or other conditions which
could cause a heat build-up in the floor pan or could let
exhaust fumes into the vehicle. See
Engine Exhaust
on page
2-26.
Fuel System Inspection
Inspect the complete fuel system for damage or leaks.
Engine Cooling System Inspection
Inspect the hoses and have them replaced if they
are cracked, swollen or deteriorated. Inspect
all pipes,
fittings and clamps; replace as needed. Clean the
outside of the radiator and air conditioning condenser.
To help ensure proper operation, a pressure test of
the cooling system and pressure cap is recommended
at least once a year.
6-1 4

Transfer Case and Front Axle
(All-Wheel Drive) Inspection
Every 12 months, or at engine oil change intervals,
check front axle and transfer case and add lubricant
when necessary.
A fluid loss could indicate a problem.
Check and have it repaired,
if needed. Check vent
hose at transfer case for kinks and proper installation.
Brake System Inspection
Inspect the complete system. Inspect brake lines and
hoses for proper hook-up, binding, leaks, cracks,
chafing, etc; Inspect
disc brake pads for wear and rotors
for surface condition. Inspect other brake parts,
including calipers, parking brake, etc. You may need to
have your brakes inspected more often if your driving
habits or conditions result in frequent braking.
6-1 5