Page 390 of 430

•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.
390
Page 392 of 430

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
seeWindshield and Wiper Blades on page 336.
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.
392
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.
393
Page 395 of 430

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.
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.
395
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.
396
Page 398 of 430

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.
398
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
Page 415 of 430

Reporting Safety Defects to
General Motors
In addition to notifying NHTSA (or Transport
Canada) in a situation like this, we certainly hope
you’ll notify us. Please call us at 1-800-862-4389,
or write:
GM Medium Duty Truck
Customer Assistance Center
P.O. Box 44947
Detroit, MI 48244
In Canada, please call us at 1-800-263-3777
(English) or 1-800-263-7854 (French). Or, write:
General Motors of Canada Limited
Customer Communication Centre, CA1-163-005
1908 Colonel Sam Drive
Oshawa, Ontario L1H 8P7
Service Publications Ordering
Information
Service Manuals
Service Manuals have the diagnosis and repair
information on engines, transmission, axle
suspension, brakes, electrical, steering, body, etc.
Transmission, Transaxle, Transfer
Case Unit Repair Manual
This manual provides information on unit
repair service procedures, adjustments, and
specifications for GM transmissions, transaxles,
and transfer cases.
Service Bulletins
Service Bulletins give technical service
information needed to knowledgeably service
General Motors cars and trucks. Each bulletin
contains instructions to assist in the diagnosis
and service of your vehicle.
In Canada, the service bulletin reference number
can be obtained by contacting your General
Motors dealer or by calling 1-800-GM-DRIVE
(1-800-463-7483). This reference number is
needed to order the service bulletin
from Helm, Inc.
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