(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
(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
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
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
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 toEngine Exhaust on page 2-37and
Running Your Engine While You Are Parked on
page 2-38.
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.
Lamps Check
Check panel lighting, warning lights, indicator lights and
interior lamps. On the outside, check: license plate
lamps, sidemarker lamps, reflectors or lights on outside
mirrors, headlamps, parking lamps, identification and
clearance lamps, taillamps, brake lamps, turn signals,
backup lamps and hazard warning flashers. Have
headlamp aim checked at once if beams seem
improperly aimed.
Glass, Mirrors, Lamps and/or
Re ectors Condition Check
Look for broken, scratched, dirty or damaged glass,
mirrors, lamps or reflectors that could reduce the view
or visibility or cause injury. Replace, clean or repair
promptly.
Door Latches Check
Check that doors close, latch and lock tightly. Check for
broken, damaged or missing parts that might prevent
tight latching.
6-27
Hood Latches Check
Check that the hood closes firmly. Check for broken,
damaged, loose or missing parts that might prevent tight
latching. Make sure the secondary latch (if equipped)
keeps the hood from opening all the way when the
primary latch is released.
Fluid Leaks Check
Check for fuel, coolant, oil or other fluid leaks by looking
at the surface beneath the vehicle after it has been
parked for awhile.
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.
6-28
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. To determine the
proper viscosity for your vehicle’s
engine, see “Engine Oil” in the
Index.
Engine Oil
(DURAMAX™
Diesel Engine)Engine oil with the letters CI-4 or
CH-4 is best for your vehicle. The
CI-4 or CH-4 designation may
appear either alone or in
combination with other API
designations, such as API CI-4/SL.
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.
Usage Fluid/Lubricant
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.
Engine Coolant
(Gasoline
Engine &
DURAMAX™
Diesel)50/50 mixture of clean, drinkable
water and use only
DEX-COOL
®Coolant. See “Engine
Coolant” in the Index.
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.
Power Steering
SystemDEXRON
®-III Automatic
Transmission Fluid.
6-29
Just dial GM Medium Duty Truck Roadside Assistance
at 1-800-862-4389 to reach a qualified representative
who can assist you in a repair or arrange a tow. We also
provide dealer information at no charge, such as
location of the nearest authorized medium duty
GM Truck dealer and their hours of operation.
Roadside Assistance is available 24 hours a day,
7 days a week, 365 days a year, including weekends
and holidays. Should you have any questions about
Roadside Assistance, call the GM Medium Duty Truck
Roadside Assistance Center or contact your dealer.
Vehicle Data Collection and
Event Data Records
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 air bag
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 or near crash event by computer systems
commonly called event data recorders (EDR).In a crash or near crash event, computer systems, such
as the Air Bag Sensing and Diagnostic Module (SDM)
in your vehicle may record information about the
condition of the vehicle and how it was operated, such
as engine speed, brake applications, throttle position,
vehicle speed, safety belt usage, air bag readiness, air
bag performance data, 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 SDM 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.
7-5