Page 2 of 430

Four-Wheel Drive
.................................. 312
Front Axle
............................................ 313
Noise Control System
........................... 314
Bulb Replacement
................................ 315
Windshield Wiper Blade Replacement
... 316
Other Service Items
.............................. 317
Tires
..................................................... 321
Appearance Care
.................................. 331
Vehicle Identification
............................. 340
Electrical System
.................................. 340
Capacities and Specifications
................ 347
Normal Maintenance
Replacement Parts
............................ 352Maintenance Schedule
.............................. 359
Maintenance Schedule
.......................... 360
Customer Assistance Information
............. 403
Customer Assistance and Information
... 404
Reporting Safety Defects
...................... 414
Index
.......................................................... 417
2
Page 175 of 430

Oil Pressure Gage
The engine oil pressure gage, on the lower right
portion of your instrument panel cluster, shows
engine oil pressure in psi (pounds per square inch)
or in kPa (kilopascals). Oil pressure may vary
with outside temperature and oil viscosity,
but readings of 30 to 40 psi (205 to 275 kPa) on
gasoline engines at operating temperature
and moderate road speeds are normal. If you
have a diesel engine, the normal operating range
should be between 35 and 70 psi (240 to 480 kPa).A reading in the low pressure zone may be
caused by a dangerously low oil level or other
problem.
If you have a Caterpillar
®diesel engine, also see
your Caterpillar®Operation & Maintenance
Manual.
{CAUTION:
Do not keep driving if the oil pressure is
low. If you do, your engine can become so
hot that it catches re. You or others
could be burned. Check your oil as soon
as possible and have your vehicle
serviced.
Notice:Lack of proper engine oil maintenance
may damage the engine. The repairs would
not be covered by your warranty. Always follow
the maintenance schedule in this manual for
changing engine oil.
United StatesCanada
175
Page 176 of 430

Low Oil Level Light
Your vehicle may have
a low oil level light.
This light should come on as a check, when you
start your engine. If the light fails to come on, have
it repaired as soon as possible so you will be
aware when the oil level is low.
Vehicles that have Caterpillar
®diesel engines may
not have a low oil level light. In this case, the light
will neither come on as a check when you start your
engine, nor will it come on to indicate a low oil level.
If this light comes on and stays on, it means your
engine is low on oil. You need to check the oil level
right away. SeeEngine Oil (Caterpillar
®DieselEngine) on page 268orEngine Oil (Gasoline
Engine) on page 268orEngine Oil (DURAMAX
®/
Isuzu Diesel Engine) on page 272for further
information.
Notice:Lack of proper engine oil maintenance
may damage the engine. The repairs would
not be covered by your warranty. Always follow
the maintenance schedule in this manual for
changing engine oil.
Change Engine Oil Light
The change engine oil
light should come on
briefly as a bulb
check when you start
the engine. If the
light does not come on,
have it serviced.
If the change engine oil light comes on and stays
on after you start the engine, have the oil
changed.
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Page 177 of 430

For additional information on when to change
engine oil for gasoline engines or DURAMAX®
diesel engines, seeEngine Oil (Caterpillar®Diesel
Engine) on page 268orEngine Oil (Gasoline
Engine) on page 268orEngine Oil (DURAMAX
®/
Isuzu Diesel Engine) on page 272andScheduled
Maintenance on page 363. To reset the change
engine oil light, seeEngine Oil Life System
(Gasoline Engine) on page 276orEngine Oil Life
System (DURAMAX
®Diesel) on page 278or
Engine Oil Life System (Caterpillar®Diesel Engine)
on page 279.
Engine Overspeed Warning Light
If your vehicle has this
light, it will come on if
your engine is operating
at too many revolutions
per minute (rpm).
It will also come on for a moment as a check
when you start your engine.
If it comes on when you’re driving, reduce your
engine speed immediately.
Engine Shutdown Warning Light
If your vehicle has the
engine shutdown
feature, this light will
come on when engine
shutdown is active.
For more information, seeEngine Alarm and
Automatic ShutdownunderStarting the Diesel
Engine on page 100.
177
Page 276 of 430

GM Goodwrench®oil of the recommended
viscosity grades meets all the requirements for
your vehicle.
Engine Oil Additives
Do not add anything to the oil. The recommended
oils with the API service symbol are all you will
need for good performance and engine protection.
When to Change Engine Oil (Vehicles
Without the Engine Oil Life System)
If you have the 6.6L V8 DURAMAX®Engine:
Change engine oil and filter every 15,000 miles
(24 000 km), or every 12 months, or every
750 hours of engine operation, whichever occurs
first. If you have the Isuzu 6H Engine: Change
engine oil and filter every 12,000 miles
(20 000 km), or every 12 months, or every
600 hours of engine operation, whichever occurs
first. SeeScheduled Maintenance on page 363.
Engine Oil Life System
(Gasoline Engine)
When to Change Engine Oil
Your vehicle has a computer system that lets you
know when to change the engine oil and filter.
This is based on engine revolutions and engine
temperature, and not on mileage. Based on driving
conditions, the mileage at which an oil change
will be indicated can vary considerably. For the oil
life system to work properly, you must reset the
system every time the oil is changed.
When the system has calculated that oil life has
been diminished, it will indicate that an oil change is
necessary. A change engine oil light will come on.
SeeChange Engine Oil Light on page 176. Change
your oil as soon as possible within the next
600 miles (1 000 km). It is possible that, if you are
driving under the best conditions, the oil life system
may not indicate that an oil change is necessary for
over a year. However, your engine oil and filter
must be changed at least once a year and at this
time the system must be reset. Your dealer has
GM-trained service people who will perform this
work using genuine GM parts and reset the system.
It is also important to check your oil regularly and
keep it at the proper level.
276
Page 283 of 430

Manual Transmission Fluid
When to Check
A good time to have it checked is when the
engine oil is checked. Refer to the Maintenance
Schedule to find out when to check and change
your manual transmission fluid. SeeScheduled
Maintenance on page 363.
How to Check and What to Use
Check the fluid level only when your engine is off,
the vehicle is parked on a level place, and the
transmission is cool enough for you to rest
your fingers on the transmission case.
To check the transmission fluid level, do the
following:
1. Remove the filler plug.
2. Check to be sure that the lubricant level is up
to the bottom of the fill opening. On heavy
duty transmissions, an inch of oil level equals
about one gallon of fluid.3. If the fluid level is good, reinstall the plug and
be sure it is fully seated. If the fluid level is
low, add more fluid as described in the
next steps. Refer to the Maintenance
Schedule to determine what kind of fluid to
use. SeePart C: Recommended Fluids
and Lubricants on page 397.
How to Add Fluid
To add transmission fluid, do the following:
1. Remove the filler plug.
2. Add fluid at the filler plug hole. Add only
enough fluid to bring the fluid level up to
the bottom of the fill opening. Refer to
the Maintenance Schedule to determine the
proper fluid to use. SeePart C:
Recommended Fluids and Lubricants on
page 397.
3. Reinstall the filler plug. Be sure the plug is
fully seated.
283
Page 295 of 430

Power Steering Fluid
SeeScheduled Maintenance on page 363to
determine when to check your power steering fluid.
How To Check Power Steering Fluid
Check your power steering fluid only when the
engine is warm. If the engine is not warm, you
probably will not get an accurate reading.
If the fluid level is between the MIN (Minimum) and
MAX (Maximum) marks, you have enough. If you
need fluid, add only enough of the proper fluid to
bring it in between the MIN and MAX marks.
If your power steering fluid level is low, this can
cause the brake or service brakes soon warning
lights to come on. In addition, the steering
effort and emergency brake distance could
increase.If either light remains on after you have added
power steering fluid to the proper level, then shut
off the engine for 10 seconds. This should
reset the brake warning lights. If one or both lights
stay on, see “Hydraulic Brake System Warning
Lights” underBrake System Warning Light
on page 169for more information.
What to Use
To determine what kind of fluid to use, see
Part C: Recommended Fluids and Lubricants on
page 397.
Notice:When adding power steering uid or
making a complete uid change, always
use the proper uid. Failure to use the proper
uid can cause leaks and damage hoses
and seals.
295
Page 297 of 430
Brakes
Brake Fluid
If your vehicle has
hydraulic brakes, there
is a brake master
cylinder in the engine
compartment on the
driver side of the vehicle.
Refer to the
Maintenance Schedule
to determine when to
check the brake fluid.
{CAUTION:
Do not add brake uid before you check
the level. If you do, you could get too
much brake uid. Brake uid could spill
on the hot engine and it can catch re.
You could be burned and your vehicle
could be damaged. See “Checking Brake
Fluid” in this section.
Checking Brake Fluid
Apply the brake pedal several times with the
ignition off. The brake fluid reservoir is in
the engine compartment on the driver side of the
vehicle. Clean one of the reservoir caps and
the area around the cap, and remove it.
The fluid level should be
even with the bottom
ring of the filler opening.
If it is low, add enough
fluid to fill the reservoir to
the proper level.
297