Page 329 of 366

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 on
Bendix-Westinghouse units.
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 automatic
transmission, your GM owner’s manual is supplemented
by an Allison Transmission
®Operator’s Manual.
Always refer to these manuals for related maintenance
services.
(2)= Refer to the Caterpillar
®Diesel Engine Operation
and Maintenance Manual for oil recommendations
and change intervals.
(3)= An Emission Control Service.
(4)= A Noise Emission Control Device.
(5)= Applies only to vehicles sold in the United States.(6)= 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.
(7)= 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 caliper assemblies. 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.
(8)= Inspect parking brake drum and linings for wear or
cracks and check linkage and adjustment.
(9)= This vehicle has the GM Oil Life System. This
system will show you when to change the engine oil and
filter – usually between 3,000 miles (5 000 km) and
7,500 miles (12 000 km) since your last oil change.
Under severe conditions, the indicator may come on
before 3,000 miles (5 000 km). Never drive your vehicle
more than 7,500 miles (12 000 km) or 12 months
without an oil and filter change.
Remember to reset the Oil Life System whenever the oil
is changed. For more information, seeChange Engine
Oil Light on page 3-39.
6-19
Page 330 of 366

(11)= Inspect rear axle air shift motor for fluid leaks.
Remove plug to check fluid level. Inspect air lines
and hoses for proper hook-up, binding, leaks, etc.
Inspect at 1,000 miles (1 600 km) and 22,500 miles
(36 000 km) and then every 22,500 miles (36 000 km)
thereafter.
(12)= Chassis Lubrication Service: Lubricate all grease
fittings in front suspension, front axle and steering
linkage. DO NOT lubricate kingpin bushings with air
pressure equipment; instead, use a hand grease gun to
ensure complete purge and eliminate sealer cap
distortion. Front axle tie rod ends, both upper and lower
kingpin fittings and both steering linkage relay rod
ends should be greased with the vehicle loaded on the
ground and wheels turned straight ahead, NOT with
the vehicle on a hoist. Apply kingpin bushing lubricant to
both upper and lower kingpin grease fittings until new
lubricant purges from between the upper shim pack and
thrust bearing. Lubricate transmission and shift
linkage, hood latches and hood hinges, parking brake
lever pivot, clevis pins and linkage, disc brake caliper
rails, clutch linkage and release bearing (if equipped),
bearing pads, propshaft universal joints, brake camshaft
bracket, slack adjusters, pedal shaft, clutch cross
shaft, clutch pedal springs and clutch cable bushing at
transmission. Lubricate suspension, axle and steeringlinkage more often when operating under dusty or
muddy conditions and in excessive off-road use.
Frequently power-washed vehicles will require more
frequent lubrication.
(13)= Check steering system:
•Look for damaged, loose or missing parts. Inspect
the steering linkage relay rod and tie rod ends for
looseness or lack of lubricant. Also look for
parts showing signs of wear or lack of lubrication.
Replace parts as needed. Also check steering gear
mounting bolts, pitman arm nut, gear housing
upper cover and side cover attaching bolts, steering
column mounting bolts and cardan joint clamp
bolts; tighten if necessary. (See service manual.)
•Inspect power steering hoses, tubes and fittings for
leaks. Hoses and lines must not be twisted, kinked
or tightly bent. Make sure clips, clamps, supporting
tubes and hoses are in place and properly
secured.
•Check steering gear for leakage around pitman
shaft and housing. If leakage is evident (lubricant
oozing out, not just oily film), leak should be
corrected immediately.
6-20
Page 331 of 366

(14)= Check front and rear suspension. Look for
damaged, loose or missing parts or parts showing signs
of wear or lack of lubrication. Replace parts as
needed.
(15)= Adjust tire pressures as indicated on the GVW
Rating label for optimum tire life. SeeTires on page 5-68
for further details. Check tires for excessive or
abnormal wear or damage. Also check for damaged
wheels. Replace wheels and/or tires as needed.
(16)= 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.
(17)= 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.(18)= Check all gasoline engine drive belts for cracks,
fraying and wear. Replace as needed.
(20)= 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.
(21)= Check shields and underhood insulation for
damage or looseness. Adjust or replace as needed.
23)= 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 6-29.
•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 oil
level at the OIL LEVEL mark between change
intervals. SeePart C: Recommended Fluids and
Lubricants on page 6-29.
6-21
Page 332 of 366

(24)= 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.
(26)= 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.
(28)= 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.
(30)= 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.
(31)= Check EGR system as described in the service
manual. SeeService Publications Ordering Information
on page 7-7.(32)= 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.
(35)= Drain, flush and refill cooling system. SeePart C:
Recommended Fluids and Lubricants on page 6-29
for what to use. Inspect hoses. Clean radiator,
condenser, pressure cap and neck. 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.
(37)= Rear axle service: Change the lubricant. See
Part C: Recommended Fluids and Lubricants on
page 6-29.
(38)= Front axle service: Re-pack upper kingpin roller
bearing.
6-22
Page 333 of 366

(39)= 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.
•Test air lines for leaks; tighten as needed. Replace
compressor filter.
•Inspect air parking brake chamber for leaks and
damage. Inspect lines and hoses for leaks,
cracks, chafing, etc. Also check all attachments for
tightness, wear or damage. Note: The spring
brake section of the rear brake diaphragms are
non-serviceable.
•Replace the air compressor filter element, mounted
on the air compressor. For remote air compressor
intake service, refer to engine air cleaner filter
replacement.
•Remove, disassemble, clean and inspect the safety
valve, standard brake chambers, quick release
valves, quick release/double check valve
combinations, parking brake control valve, double
check valves, pressure protection valves and
alcohol injector (if equipped).
•Remove, disassemble and clean the application
valve; replace parts showing wear.
•Remove, disassemble, clean and inspect the spring
brake control valve; replace rubber parts.
(40)= Clean and lubricate air brake automatic slack
adjuster. Check pushrod travel and auto adjustment
operation. Have serviced if needed.
(41)= Air brake chamber service: Check operation,
mounting, clamps and air lines and check for leaks.
(42)= Trailer brake hand control valve service: Check
operation; lubricate cam and follower.
(46)= Tighten the wheel stud nuts to the specified
torque values at 100 miles (160 km). Thereafter, tighten
them 1,000 miles (1 600 km) after each time the
wheel is removed. SeeTightening the Wheel Nuts on
page 5-71.
6-23
Page 334 of 366

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.
For your safety and that of others, any of the
safety-related components that may have been
damaged in an accident should be checked and any
needed repairs made before operating the vehicle.
At the minimum, these routine checks should be made
every 6 months or 6,000 miles (10 000 km), whichever
occurs first. Whenever repairs are needed, have
them completed before operating the vehicle.
At Each Fuel Fill
It is important for you or a service station attendant to
perform these underhood checks at each fuel ll.
Engine Oil Level Check
Check the engine oil level and add the proper oil if
necessary. See “Engine Oil” in the Index for further
details.
Engine Coolant Level Check
Check the engine coolant level and add DEX-COOL®
coolant mixture if necessary. See “Engine Coolant”
in the Index for further details.
Windshield Washer Fluid Level Check
Check the windshield washer fluid level in the windshield
washer tank and add the proper fluid if necessary.
SeeCleaning the Outside of Your Vehicle on page 5-80
for further details.
Tire In ation Check
Check tire inflation cold. Make sure tires are inflated to
the pressures specified on the GVW Rating label.
SeeLoading Your Vehicle on page 4-33andTires on
page 5-68for further details.
6-24
Page 335 of 366

At Least Twice a Year
Restraint System Check
Make sure the safety belt reminder light (if equipped)
and all your belts, buckles, latch plates, retractors
and anchorages are working properly. Look for any other
loose or damaged safety belt system parts. If you see
anything that might keep a safety belt system from doing
its job, have it repaired. Have any torn or frayed
safety belts replaced.
Wiper Blade Check
Inspect wiper blades for wear or cracking. Replace
blade inserts that appear worn or damaged or that
streak or miss areas of the windshield. Also see
Cleaning the Outside of Your Vehicle on page 5-80.
Weatherstrip Lubrication
Silicone grease on weatherstrips will make them last
longer, seal better, and not stick or squeak. Apply
silicone grease with a clean cloth. During very cold,
damp weather more frequent application may be
required. Part C tells you what to use.
Body Lubrication Service
Lubricate all exposed surfaces such as door checks,
door lock bolts, lock strike plates, door hinge bushings,
latches and dovetail bumper wedges. Where oil
holes are provided a dripless oil can be used. The seat
adjusters, seat track, door weatherstrips and rubber
cap bumpers should also be lubricated. Part C tells you
what to use. More frequent lubrication may be required
when exposed to a corrosive environment.
Parking Brake Check
Park on a fairly steep hill and hold the vehicle with the
parking brake only. This checks holding ability.
6-25
Page 336 of 366

Starter Switch Check
{CAUTION:
When you are doing this inspection, the
vehicle could move suddenly. If the vehicle
moves, you or others could be injured.
1. Before you start, be sure you have enough room
around the vehicle.
2. Firmly apply both the parking brake and the regular
brakes. See “Parking Brake” if necessary.
Do not use the accelerator pedal, and be ready to
turn off the engine immediately if it starts.
3. On automatic transmission vehicles, try to start the
engine in each gear. The starter should work only
in PARK (P), if equipped, or NEUTRAL (N). If
the starter works in any other position, your vehicle
needs service.
Automatic Transmission Shift Indicator
Check
Check that the indicator points to the gear chosen.
Steering Check
Be alert for any changes in steering action, abnormal
front tire wear or steering wheel position. An inspection
or service is needed when the steering wheel is
harder to turn or has too much free play, or if there are
strange sounds when turning or parking.
Brake System Check
Be alert to illumination of the low air warning lamp or for
the tone alarm, or changes in braking action, such as
repeated pulling to one side, unusual sounds when
braking or increased brake pedal travel. Make sure air
brake system reservoirs are drained daily with full
system air pressure, and check system for leaks. Any of
these conditions could indicate the need for brake
system inspection and/or service.
Engine Cooling System Service
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.
6-26