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Rear Axle
When to Check Lubricant
Refer to the Maintenance Schedule to determine
how often to check the lubricant. SeeScheduled
Maintenance (Gasoline Engine) on page 399.
How to Check Lubricant
To get an accurate reading, the vehicle should be
on a level surface.If you have the 1500 Series, the proper level is
from 5/8 inch (15 mm) to 1 5/8 inch (40 mm) below
the bottom of the filler plug hole. The proper
level for the 2500 and 3500 Series is from
0 to 1/4 (6 mm) below the bottom of the filler
plug hole. Add only enough fluid to reach
the proper level.
What to Use
Refer to the Maintenance Schedule to determine
what kind of lubricant to use. SeeRecommended
Fluids and Lubricants on page 409.
Front Axle
When to Check and Change Lubricant
Refer to the Maintenance Schedule to determine
how often to check the lubricant and when to
change it. SeeScheduled Maintenance (Gasoline
Engine) on page 399.
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How to Check Lubricant
To get an accurate reading, the vehicle should be
on a level surface.
If the level is below the
bottom of the filler plug
hole, you may need
to add some lubricant.
When the differential is cold, add enough lubricant
to raise the level to 3/8 inch (10 mm) below the
filler plug hole.
When the differential is at operating temperature
(warm), add enough lubricant to raise the level
to the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine
what kind of lubricant to use. SeeRecommended
Fluids and Lubricants on page 409.
Noise Control System
Tampering with Noise Control
System Prohibited
The following information relates to compliance
with federal noise emission standards for vehicles
with a Gross Vehicle Weight Rating (GVWR) of
more than 10,000 lbs (4 536 kg). The Maintenance
Schedule provides information on maintaining
the noise control system to minimize degradation
of the noise emission control system during
the life of your vehicle. The noise control system
warranty is given in your warranty booklet.
These standards apply only to vehicles sold in the
United States.
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Federal law prohibits the following acts or the
causing thereof:
1. The removal or rendering inoperative by any
person, other than for purposes of
maintenance, repair or replacement, of any
device or element of design incorporated into
any new vehicle for the purpose of noise
control, prior to its sale or delivery to
the ultimate purchaser or while it is in use; or
2. The use of the vehicle after such device or
element of design has been removed or
rendered inoperative by any person.
Among those acts presumed to constitute
tampering are the acts listed below.
Insulation:
•
Removal of the noise shields or any
underhood insulation.
Engine:
•
Removal or rendering engine speed governor,
if the vehicle has one, inoperative so as to
allow engine speed to exceed manufacturer
specifications.
Fan and Drive:
•
Removal of fan clutch, if the vehicle has one,
or rendering clutch inoperative.
•Removal of the fan shroud, if the vehicle
has one.
Air Intake:
•
Removal of the air cleaner silencer.
•Modification of the air cleaner.
Exhaust:
•
Removal of the muffler and/or resonator.
•Removal of the exhaust pipes and exhaust
pipe clamps.
Fuel Operated Heater (FOH) — Diesel
Engine:
•
Removal of the muffler.
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6. Remove the bulb socket by squeezing the tab
on the side of the socket while turning it
counterclockwise.
7. Turn the bulb counterclockwise to remove it.
8. Install a new bulb.
9. Reverse the steps to reinstall the taillamp
assembly.
Replacement Bulbs
Exterior Lamp Bulb Number
Back-up, Rear Parking,
Stoplamp, and Turn Signal Lamp3157
CHMSL 912
Front Parking and Turn
Signal Lamp3157KX
Front Sidemarker Lamp 194
Headlamps
Composite High-Beam 9005
Composite Low-Beam 9006GS
Sealed Beam Headlamp H6054
For replacement bulbs not listed here, contact
your dealer.
Windshield Wiper Blade
Replacement
Windshield wiper blades should be inspected for
wear and cracking. SeeScheduled Maintenance
(Gasoline Engine) on page 399for more
information on wiper blade inspection.
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Page 350 of 452

Dual Tire Operation
When the vehicle is new, or whenever a wheel,
wheel bolt or wheel nut is replaced, check the
wheel nut torque after 100, 1,000 and 6,000 miles
(160, 1 600 and 10 000 km) of driving. For proper
wheel nut tightening information, see “Removing
the Flat Tire and Installing the Spare Tire” later in
this section, underChanging a Flat Tire on
page 360. Also see “Wheel Nut Torque” under
Capacities and Speci cations on page 393.
The outer tire on a dual wheel setup generally
wears faster than the inner tire. Your tires will wear
more evenly and last longer if you rotate the
tires periodically. SeeTire Inspection and Rotation
on page 351. Also seeScheduled Maintenance
(Gasoline Engine) on page 399.{CAUTION:
If you operate your vehicle with a tire
that is badly underin ated, the tire can
overheat. An overheated tire can lose air
suddenly or catch re. You or others could
be injured. Be sure all tires (including the
spare) are properly in ated.
SeeTires on page 340andIn ation - Tire
Pressure on page 348for more information on
proper tire inflation.
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Tire Inspection and Rotation
Tires should be rotated every 5,000 to 8,000 miles
(8 000 to 13 000 km).
Any time you notice unusual wear, rotate your
tires as soon as possible and check wheel
alignment. Also check for damaged tires or wheels.
SeeWhen It Is Time for New Tires on page 353
andWheel Replacement on page 357for
more information.
Make sure the spare tire is stored securely. Push,
pull, and then try to rotate or turn the tire. If it
moves, use the ratchet/wheel wrench to tighten the
cable. SeeChanging a Flat Tire on page 360.
If your vehicle has dual rear wheels, also seeDual
Tire Operation on page 350.
The purpose of regular rotation is to achieve more
uniform wear for all tires on the vehicle. The
first rotation is the most important. SeeScheduled
Maintenance (Gasoline Engine) on page 399.If your vehicle has single rear wheels, always use
the correct rotation patterns shown here when
rotating your vehicle’s tires. Do not include
the spare tire in the tire rotation, if the spare
tire/wheel assembly does not match your vehicle’s
road tires and wheels in size and type.
Single Rear Wheels
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If a Tire Goes Flat
It is unusual for a tire to blowout while you are
driving, especially if you maintain your vehicle’s
tires properly. If air goes out of a tire, it is
much more likely to leak out slowly. But if you
should ever have a blowout, here are a few tips
about what to expect and what to do:
If a front tire fails, the flat tire will create a drag
that pulls the vehicle toward that side. Take your
foot off the accelerator pedal and grip the
steering wheel firmly. Steer to maintain lane
position, and then gently brake to a stop well out
of the traffic lane.
A rear blowout, particularly on a curve, acts much
like a skid and may require the same correction
you would use in a skid. In any rear blowout
remove your foot from the accelerator pedal. Get
the vehicle under control by steering the way
you want the vehicle to go. It may be very bumpy
and noisy, but you can still steer. Gently brake
to a stop, well off the road if possible.{CAUTION:
Lifting a vehicle and getting under it to do
maintenance or repairs is dangerous
without the appropriate safety equipment
and training. The jack provided with your
vehicle is designed only for changing a
at tire. If it is used for anything else, you
or others could be badly injured or killed
if the vehicle slips off the jack. Use the
jack provided with your vehicle only for
changing a at tire.
If a tire goes flat, the next part shows how to use the
jacking equipment to change a flat tire safely.
Changing a Flat Tire
If a tire goes flat, avoid further tire and wheel
damage by driving slowly to a level place. Turn on
your vehicle’s hazard warning flashers. SeeHazard
Warning Flashers on page 146for more
information.
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Underbody Maintenance
Chemicals used for ice and snow removal and
dust control can collect on the underbody. If these
are not removed, corrosion and rust can develop
on the underbody parts such as fuel lines,
frame, floor pan, fuel operated heater (FOH) and
exhaust system even though they have corrosion
protection.
At least every spring, flush these materials from
the underbody with plain water. Clean any
areas where mud and debris can collect. Dirt
packed in close areas of the frame should
be loosened before being flushed. Your dealer or
an underbody car washing system can do this
for you.
Chemical Paint Spotting
Some weather and atmospheric conditions can
create a chemical fallout. Airborne pollutants can
fall upon and attack painted surfaces on the
vehicle. This damage can take two forms: blotchy,
ring-shaped discolorations, and small, irregular
dark spots etched into the paint surface.
Although no defect in the paint job causes this,
GM will repair, at no charge to the owner, the
surfaces of new vehicles damaged by this fallout
condition within 12 months or 12,000 miles
(20 000 km) of purchase, whichever occurs first.
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