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•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, service brake chambers, quick
release valves, quick release/double check
valve combinations, parking brake control
valve, double check valves, pressure
protection valves, and ether 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.
(33)= Clean and lubricate air brake automatic
slack adjuster. Check pushrod travel and
auto adjustment operation. Have serviced
if needed.(34)= Air brake chamber service: Check operation,
mounting clamps, and air lines and check for leaks.
(35)= Trailer brake hand control valve service:
Check operation; lubricate cam and follower.
(36)= 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 325.
(37)= Inspect and clean any accumulated dirt,
gravel, or other foreign objects from the valves and
valve boots as needed. Using light oil, lubricate
brake pedal to brake application valve linkage
components. Check any rubber boots for cracks,
holes, or deterioration and replace if necessary.
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Page 391 of 430

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. SeeEngine Oil (Caterpillar®
Diesel Engine) on page 268orEngine Oil
(Gasoline Engine) on page 268orEngine Oil
(DURAMAX
®/Isuzu Diesel Engine) on page 272.
Engine Coolant Level Check
Check the engine coolant level and add
DEX-COOL®coolant mixture if necessary. See
Engine Coolant (Gas and DURAMAX®/Isuzu
Engines) on page 284orEngine Coolant
(Caterpillar
®Diesel Engines) on page 287.
Windshield Washer Fluid Level Check
Check the windshield washer fluid level in the
windshield washer fluid reservoir and add
the proper fluid if necessary. SeeWindshield
Washer Fluid on page 296.
Tire In ation Check
Check tire inflation cold. Make sure the tires are
inflated to the correct pressures. SeeLoading Your
Vehicle on page 238andIn ation - Tire Pressure
on page 322.
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Page 393 of 430

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.
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.
On manual transmission vehicles, the starter
should work only when the clutch pedal is
all the way down.
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.
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Page 394 of 430

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.
Exhaust System Check
Be alert for any changes in the sound of the
exhaust system or any smell of fumes. These
are signs the system may be leaking. Have
it checked and/or repaired at once. Refer to
Engine Exhaust on page 131andRunning
the Engine While Parked on page 132.
Windshield Wipers and Washers Check
Check operation and condition of the wiper
blades. Check the flow of the washer spray.
Defroster Check
Move the control to the defrost symbol and the fan
to HI or the high symbol. Then check the airflow
from the ducts at the inside base of the windshield.
Mirrors and Sun Visors Check
Check that friction joints hold mirrors and sun
visors in place.
Seat Adjuster Check
When adjusting a manual seat, be sure seat
adjusters latch by attempting to move the seat
after latching.
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Page 396 of 430

Underbody Inspection
Corrosive materials used for ice, snow removal,
and dust control can collect on the underbody.
If these materials are not removed, accelerated
corrosion (rust) can occur on underbody parts
such as fuel lines, frame, floor pan, and exhaust
system. At least every spring, flush these materials
from the underbody with plain water. Take care
to clean well any areas where mud and other
debris can collect. Sediment packed in closed
areas of the frame should be loosened before
being flushed.
Engine Cover Check
Check that the cab’s engine cover and seal
(if equipped) are not torn or damaged.
Be sure that the cover is clamped down firmly
to the floor.
At Least Once a Year
Key Lock Cylinders Service
Lubricate the key lock cylinders with the lubricant
specified in Part C.
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.
Tractor Protection (Breakaway)
Valve Check
On air brake models, remove, disassemble,
clean, and inspect the tractor protection
(breakaway) valve.
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Page 397 of 430

Part C: Recommended Fluids
and Lubricants
Fluids and lubricants identified below by name,
part number, or specification may be obtained
from your dealer.
Usage Fluid/Lubricant
Engine Oil
(Gasoline
Engine)Engine oil which meets GM
Standard GM6094M and displays
the American Petroleum Institute
Certified for Gasoline Engines
starburst symbol. GM Goodwrench
®
oil meets all the requirements for
your vehicle. To determine the
proper viscosity for your vehicle’s
engine, see “Engine Oil” in the
Index.
Usage Fluid/Lubricant
Engine Oil
(DURAMAX
®/
Isuzu Diesel
Engines)Engine oil with the letters CJ-4
or CI-4 is best for your vehicle.
The CJ-4 or CI-4 designation
may appear either alone or in
combination with other API
designations, such as API CJ-4/SM.
These letters show American
Petroleum Institute levels of quality.
To determine the preferred viscosity
for your vehicle’s diesel engine,
see “Engine Oil” in the Index.
Engine Oil
(Caterpillar
®
Diesel Engine)See the Caterpillar
®Operation &
Maintenance Manual for engine
oil recommendations.
Engine Coolant
(Caterpillar
®
Diesel Engine)See the Caterpillar
®Operation &
Maintenance Manual for engine
coolant recommendations.
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Usage Fluid/Lubricant
Engine Coolant
(Gasoline
Engine &
DURAMAX
®/
Isuzu Diesel)50/50 mixture of clean, drinkable
water and use only DEX-COOL
®
Coolant. SeeEngine Coolant (Gas
and DURAMAX®/Isuzu Engines)
on page 284orEngine Coolant
(Caterpillar
®Diesel Engines)
on page 287.
Hydraulic Brake
SystemDelco
®Supreme 11 Brake Fluid
or equivalent DOT-3 brake fluid.
Windshield
Washer SolventGM Optikleen
®Washer Solvent.
Clutch Bearing
LubricantClutch Bearing Lubricant
(GM Part No. 12378484 or
equivalent NLGI #3 consistency).
Exhaust Brake
Ball Joint Cap
LubricantHigh-Temperature Grease
(GM Part No. U.S. 1051344,
in Canada 903037) or
NLGI #3 consistency.
Usage Fluid/Lubricant
Power Steering
SystemDEXRON
®-VI Automatic
Transmission Fluid.
Manual
TransmissionSynthetic Manual Transmission
Fluid (GM Part No. U.S. 12345724,
in Canada 10953510).
Automatic
TransmissionSee the Allison Transmission
®
Operator’s Manual for correct
transmission fluid.
Key Lock
CylindersMulti-Purpose Lubricant, Superlube
(GM Part No. U.S. 12346241,
in Canada 10953474).
Chassis
LubricationChassis Lubricant
(GM Part No. U.S. 12377985,
in Canada 88901242) or lubricant
meeting requirements of NLGI #2,
Category LB or GC-LB.
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Page 409 of 430

Vehicle Data Collection and
Event Data Recorders
Your vehicle, like other modern motor vehicles, has
a number of sophisticated computer systems that
monitor and control several aspects of the vehicle’s
performance. Your vehicle uses on-board vehicle
computers to monitor emission control components
to optimize fuel economy, to monitor conditions for
airbag deployment and, if so equipped, to provide
anti-lock braking and to help the driver control
the vehicle in difficult driving situations. Some
information may be stored during regular operations
to facilitate repair of detected malfunctions; other
information is stored only in a crash event by
computer systems, such as those commonly
called event data recorders (EDR).
In a crash event, computer systems, such as the
Airbag Sensing and Diagnostic Module (SDM)
in your vehicle may record information about the
condition of the vehicle and how it was operated,
such as data related to engine speed, brake
application, throttle position, vehicle speed,safety belt usage, airbag readiness, airbag
performance, and the severity of a collision.
This information has been used to improve vehicle
crash performance and may be used to improve
crash performance of future vehicles and
driving safety. Unlike the data recorders on many
airplanes, these on-board systems do not
record sounds, such as conversation of vehicle
occupants.
To read this information, special equipment is
needed and access to the vehicle or the device
that stores the data is required. GM will not access
information about a crash event or share it with
others other than:
•with the consent of the vehicle owner or,
if the vehicle is leased, with the consent of
the lessee,
•in response to an official request of police or
similar government office,
•as part of GM’s defense of litigation through
the discovery process, or
•as required by law.
409