Electric Air Compressor
Your vehicle may have an electric air compressor. This
compressor is used to run options that require
pressurized air, such as air horn, air seat, 7.8L engine
exhaust restrictor, or 7.8L engine exhaust brake.
The air compressor is used when vehicles are not
equipped with an air brake system.
The air supply for this
system must be
maintained by releasing
the drain valve to eject any
moisture that may have
built up in the system.
It is recommended that this system be drained on a
weekly basis.
Clutch Pedal Free Travel
If you have a V8 engine and a manual transmission,
your clutch will need adjustment when pedal free travel
gets down to about 1/4 inch (32 mm), as measured
at the clutch pedal pad. You should have 1 1/2 to
2 inches (38 to 51 mm) of clutch pedal free travel.
If your clutch ever needs service, be sure to use only
GM clutch replacement parts.
Chassis Lubrication
Your Maintenance Schedule provides all of the required
chassis lubrication intervals and identifies proper
lubricants to use. Be sure to see your Maintenance
Schedule before performing any chassis lubrication
service. To determine location of chassis lubrication
items, use the following charts.
5-51
2. Push the release lever and slide the wiper assembly
toward the driver’s side of the vehicle.
3. Install a new blade by reversing Steps 1 and 2.
Other Service Items
Fuel Filter
Fuel Filter (Gasoline Engines)
The steel fuel filter is located near the engine
compartment on the driver’s side of the vehicle.
See your Maintenance Schedule for recommended
service intervals.
If your vehicle is equipped with the optional Davco
spin-on type filter, it is located on the driver’s side
frame rail.
5-66
Fuel Filter (Diesel Engines)
If you have a diesel engine, your fuel filter is located in
the engine compartment on the driver’s side of the
vehicle, or along the driver’s side frame rail. SeeFuel
Filter Replacementearlier in this section for further
information.
Also seeScheduled Maintenance on page 6-5for
recommended service intervals.
Primary Fuel Filter and Water
Separator
If you have a diesel
engine, you may have this
spin-on filter. It is located
on the driver’s side
frame rail.It has a clear plastic drain bowl at the bottom. Check
the drain bowl occasionally for any water or particles.
To drain the bowl, do the following:
1. Shut off the engine.
2. Partially open the drain valve at the bottom of
the filter.
SeeEngine Oil (Caterpillar
®Diesel Engine) on
page 5-22orEngine Oil (DURAMAX®Diesel) on
page 5-22orEngine Oil (Gasoline Engine) on page 5-26
for proper disposal procedures.
5-67
Part A: Scheduled Maintenance
Services
In this part are scheduled maintenance services which
are to be performed at the mileage intervals specified.
Using the Maintenance Schedule
We at General Motors want to help keep your vehicle in
good working condition. But we do not know exactly
how you will drive it. You may drive very short distances
only a few times a week. Or you may drive long
distances all the time in very hot, dusty weather. You
may use your vehicle in making deliveries or in
many other ways.
Because of all the different ways people use their
vehicles, maintenance needs vary. You may need more
frequent checks and replacements. So please read
the following and note how you drive. If you have any
questions on how to keep your vehicle in good condition,
see your dealer.This part tells you the maintenance services you should
have done and when to schedule them.
When you go to your dealer for your service needs, you
will know that GM-trained and supported service
people will perform the work using genuine GM parts.
The proper fluids and lubricants to use are listed in
Part C. Make sure whoever services your vehicle uses
these. All parts should be replaced and all necessary
repairs done before you or anyone else drives the
vehicle.
This schedule is for vehicles that:
•carry passengers and cargo within recommended
limits. You will find limits on your vehicle’s GVW
Rating label. SeeLoading Your Vehicle on
page 4-32.
•are driven on reasonable road surfaces within legal
driving limits.
•use the recommended fuel. SeeWhat Fuel to Use
on page 5-8.
6-4
Scheduled Maintenance
Supplements
If your vehicle has a Caterpillar®diesel engine, your
owner’s manual is supplemented by the Caterpillar®
Diesel Engine Operation & Maintenance Manual. If your
vehicle has an Allison transmission, your owner’s
manual is supplemented by an Allison
Transmission
®Operator’s Manual. Always refer to these
manuals for related maintenance services.
Scheduled Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be repeated after 100,000 miles
(166 000 km) at the same intervals for the life of
this vehicle. The services shown after 100,000 miles
(166 000 km) should be repeated at the same miles (km)
after those intervals for the life of this vehicle.Gasoline engine vehicles and some DURAMAX
®diesel
engine vehicles have a computer that lets you know
when to change your engine oil. This is not based
on mileage, but on engine operation and engine
temperature. When the computer has calculated that the
oil needs changing, the Engine Oil Life System will
indicate that a change is necessary. SeeEngine Oil Life
System (Gasoline Engine) on page 5-29orEngine Oil
Life System (DURAMAX
®Diesel) on page 5-31or
Engine Oil Life System (Caterpillar®Diesel Engine) on
page 5-32.
The “Footnotes” at the end of this Maintenance
Schedule further explain maintenance services.
SeeService Publications Ordering Information on
page 7-8.
100 Miles (160 km)
❑Wheel stud nut service.(36)
1,000 Miles (1 600 km)
❑Wheel stud nut service.(36)
❑Rear axle air shift motor service.(10)
6-5
200,000 Miles (320 000 km)
❑Remove, disassemble, clean, and inspect the air
brake trailer supply valve (or every 2 years, or
every 7,200 hours, whichever occurs first).
❑Diesel Engine Only: Inspect engine drive belt;
replace as necessary.
250,000 Miles (400 000 km)
❑Four-wheel drive only: Front axle service.(30)
❑Four-wheel drive only: Transfer case service.(30)
❑Rear axle service — Eaton
®, Rockwell®, Spicer®
axles (or every 36 months, whichever occurs
first).(30)
❑Manual transmission (except ZF 6-speed) fluid
replacement (or every 60 months, whichever
occurs first).
300,000 Miles (480 000 km)
❑Remove, disassemble, clean, and inspect the air
brake air dryer (or every 3 years, or 10,800 hours,
whichever occurs first). Replace desiccant.
Footnotes
† = The U.S. Environmental Protection Agency or the
California Air Resources Board has determined that the
failure to perform this maintenance item will not nullify
the emission warranty or limit recall liability prior to
the completion of the vehicle’s useful life. We, however,
urge that all recommended maintenance services be
performed at the indicated intervals and the
maintenance be recorded.
(1)= If your vehicle has an Allison Transmission
®, your
GM owner manual is supplemented by an Allison
Transmission
®Operator’s Manual. Always refer to these
manuals for related maintenance services.
(2)= An Emission Control Service.
(3)= A Noise Emission Control Device.
(4)= Applies only to vehicles sold in the United States.
(5)= Check fluid level in brake master cylinder,
power steering pump, axle, transmission and hydraulic
spring parking brake pump (if equipped). A low fluid
level in the brake master cylinder can indicate
worn brake linings and should be checked accordingly.
6-21
(14)= Adjust tire pressures as indicated on the Gross
Vehicle Weight (GVW) Rating label for optimum tire life.
SeeTires on page 5-70for further details. Check
tires for excessive or abnormal wear or damage. Also
check for damaged wheels. Replace wheels and/or tires
as needed.
(15)= Check spring-to-axle U-bolts and shackle bolts
for proper torque. See the service manual for torque
sequence and specifications. When parts are replaced,
the torque must be checked and adjusted more often
during the first 6,000 miles (10 000 km). Check torque at
500 miles (800 km) and 2,000 miles (3 000 km) after
first use of parts.
(16)= Check complete exhaust system and cab areas
near the exhaust system for broken, damaged,
missing, or out-of-position parts. Also inspect for open
seams, holes, loose connections, or other conditions
which could let exhaust fumes seep into the driver
compartment. Needed repairs should be made at once.
To help maintain system integrity, replace exhaust
pipes whenever a new muffler is put on.
(17)= Check all gasoline engine drive belts for cracks,
fraying, and wear. Replace as needed.
(18)= Adjust valve lash. Incorrect valve clearance
will result in increased engine noise and reduced engine
output.(19)= With the engine off and below normal operating
temperature, check to see that the thermostatically
controlled engine cooling fan can be rotated by hand on
viscous-operated drives. Replace as needed.
(20)= Check shields and underhood insulation for
damage or looseness. Adjust or replace as needed.
(21)= Inspect parking brake drum and linings for wear
or cracks and check linkage and adjustment.
(22)= Wheel bearing service:
•Grease type — Clean, inspect, and lubricate with
the proper wheel bearing grease at designated
intervals or when hubs are removed. SeePart C:
Recommended Fluids and Lubricants on page 6-32.
•Oil-filled type — Some wheel bearings are
lubricated by rear axle lubricant. When you have
oil-filled hubs, use lubricant identical to that used in
your rear axle. Lubricant change intervals are
the same for front and rear axles. However, you
must maintain the proper oil level between change
intervals. SeeFront Wheel Bearings with Oil-Filled
Hubs on page 5-69andPart C: Recommended
Fluids and Lubricants on page 6-32.
(23)= Check the air intake system installation to see
that gaskets are seated properly and all hose
connections, fasteners, and other components are tight.
Tighten connections and fasteners or replace parts
as required.
6-24
(24)= Evaporative Control System Service, if equipped:
Check all fuel and vapor lines and hoses for proper
connections and correct routing (or every 24 months,
whichever occurs first). Replace parts as needed.
(25)= Replace spark plugs. Inspect wires for damage.
Check the wire boot and boot heat shield fit at spark
plugs and coil. Replace parts as needed.
(26)= Check the fuel tank, fuel cap and fuel lines for
damage which could cause leakage. Inspect fuel cap for
correct sealing ability and any indications of damage.
Check fuel cap gasket for even filler neck imprint.
Replace parts as needed.
(27)= Check Exhaust Gas Recirculation (EGR) system
as described in the service manual. SeeService
Publications Ordering Information on page 7-8.
(28)= Inspect Electronic Vacuum Regulator Valve
(EVRV) filter for excessive contamination or plugging. If
needed, clean filter with solution of soap and water,
let dry and install.
(29)= Drain, flush, and refill cooling system. This
service can be complex; you should have your dealer
perform this service. SeePart C: Recommended Fluids
and Lubricants on page 6-32for what to use. Inspect
hoses. Clean radiator, condenser, pressure cap, andneck. Pressure test cooling system and pressure cap. For
Caterpillar®diesel engines, always refer to the
Caterpillar®Diesel Engine Operation & Maintenance
Manual for coolant recommendations and change
intervals.
(30)= Change the lubricant. SeePart C: Recommended
Fluids and Lubricants on page 6-32.
(31)= Front axle service: Re-pack upper kingpin
roller bearing.
(32)= Air brake service:
•Inspect brake lines and hoses for proper hook-up,
binding, leaks, cracks, chafing, etc. Inspect drum
brake linings for wear or cracks. Inspect other brake
parts at each wheel, including drums and wheel
speed sensor wiring. Check brake pedal for
excessive free play or travel (or every 6 months,
whichever occurs first) and have serviced if needed.
Check brakes more often if driving habits and
conditions result in frequent braking. Replace air
dryer cartridge only if excessive oil or moisture
is present. A small amount of oil in the system is
normal and should not be considered as a reason to
replace the cartridge.
6-25