
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.
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 the
vehicle has one, 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.
6-29

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 the
vehicle has one, 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.
6-30

Usage Fluid/Lubricant
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.
Front Wheel
Bearings
(Except Oil
Filled Hubs)Wheel bearing lubricant meeting
requirements of NLGI #2,
Category GC or GC-LB
(GM Part No. U.S. 1051344, in
Canada 993037).
Front Wheel
Bearings with
Oil Filled HubsSAE 75W-90 Synthetic Axle
Lubricant for Medium Duty Trucks
(GM Part No. U.S. 89021675, in
Canada 10953512).
Transfer Case
(Four-Wheel
Drive)Manual Transmission Fluid
(GM Part No. U.S. 88861800, in
Canada 88861801).
Front Axle
(Four-Wheel
Drive)SAE 75W-90 Synthetic Axle
Lubricant for Medium Duty Trucks
(GM Part No. U.S. 89021675, in
Canada 10953512).
Usage Fluid/Lubricant
Rear Axle and
Rear HubsSAE 75W-90 Synthetic Axle
Lubricant for Medium Duty Trucks
(GM Part No. U.S. 89021675, in
Canada 10953512).
Rear Axle Shift
Motor LubricantRefrigerant Oil
(GM Part No. U.S. 5416939, in
Canada 10953496).
Propshafts and
SplinesWheel bearing lubricant meeting
requirements of NLGI #2, Category
GC or GC-LB
(GM Part No. U.S. 1051344, in
Canada 993037).
Cab — Door
Hinges and
LatchesMulti-Purpose Lubricant, Superlube
(GM Part No. U.S. 12346241, in
Canada 10953474).
Weatherstrip
ConditioningWeatherstrip Lubricant
(GM Part No. U.S. 3634770, in
Canada 10953518) or
Dielectric Silicone Grease
(GM Part No. U.S. 12345579, in
Canada 992887).
Weatherstrip
SqueaksSynthetic Grease with
Teflon, Superlube
(GM Part No. U.S. 12371287, in
Canada 10953437).
6-32

Vehicle Data Recording and
Privacy
Vehicle Data Recording and Privacy
(Isuzu 7.8L L6 Engine)
Your GM vehicle has a number of sophisticated
computers that record information about the vehicle’s
performance and how it is driven. For example,
your vehicle uses computer modules to monitor and
control engine and transmission performance, to monitor
the conditions for airbag deployment and deploy
airbags in a crash and, if so equipped, to provide
antilock braking to help the driver control the vehicle.
These modules may store data to help your
dealer/retailer technician service your vehicle. Some
modules may also store data about how you operate the
vehicle, such as rate of fuel consumption or average
speed. These modules may also retain the owner’s
personal preferences, such as radio pre-sets, seat
positions, and temperature settings.
Event Data Recorders
(Isuzu 7.8L L6 Engine)
This vehicle has an Event Data Recorder (EDR). The
main purpose of an EDR is to record, in certain crash or
near crash-like situations, such as an airbag deployment
or hitting a road obstacle, data that will assist in
understanding how a vehicle’s systems performed. The
EDR is designed to record data related to vehicle
dynamics and safety systems for a short period of time,
typically 30 seconds or less. The EDR in this vehicle
is designed to record such data as:
•How various systems in your vehicle were operating
•Whether or not the driver and passenger safety
belts were buckled/fastened
•How far, if at all, the driver was pressing the
accelerator and/or brake pedal
•How fast the vehicle was traveling
This data can help provide a better understanding of the
circumstances in which crashes and injuries occur.
Important:EDR data is recorded by your vehicle only
if a non-trivial crash situation occurs; no data is
recorded by the EDR under normal driving conditions
and no personal data (e.g., name, gender, age,
and crash location) is recorded. However, other parties,
such as law enforcement, could combine the EDR
data with the type of personally identifying data routinely
acquired during a crash investigation.
7-11

To read data recorded by an EDR, special equipment is
required, and access to the vehicle or the EDR is
needed. In addition to the vehicle manufacturer, other
parties, such as law enforcement, that have the special
equipment, can read the information if they have
access to the vehicle or the EDR.
GM will not access this data or share it with others
except: 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. Data that GM collects or receives may also be used
for GM research needs or may be made available to
others for research purposes, where a need is shown
and the data is not tied to a specific vehicle or
vehicle owner.
OnStar®(Isuzu 7.8L L6 Engine)
If your vehicle has OnStar and you subscribe to the
OnStar services, please refer to the OnStar Terms and
Conditions for information on data collection and use.
Navigation System
(Isuzu 7.8L L6 Engine)
If your vehicle has a navigation system, use of the
system may result in the storage of destinations,
addresses, telephone numbers, and other trip
information. Refer to the navigation system operating
manual for information on stored data and for deletion
instructions.
Radio Frequency Identi cation
(RFID) (Isuzu 7.8L L6 Engine)
RFID technology is used in some vehicles for functions
such as tire pressure monitoring and ignition system
security, as well as in connection with conveniences
such as key fobs for remote door locking/unlocking and
starting, and in-vehicle transmitters for garage door
openers. RFID technology in GM vehicles does not use
or record personal information or link with any other
GM system containing personal information.
7-12

A
Accessories and Modifications............................ 5-4
Adding a Snow Plow or Similar Equipment.........4-23
Adding Equipment to Your Airbag-Equipped
Vehicle.......................................................1-59
Additives, Fuel................................................. 5-8
Add-On Electrical Equipment...........................5-102
Air Cleaner/Filter, Engine.................................5-39
Air Conditioning..............................................3-20
Air Pressure Gage..........................................3-46
Air Suspension...............................................2-44
Air Suspension Seats........................................ 1-6
Airbag
Off Light.....................................................3-29
Readiness Light..........................................3-28
Airbag System................................................1-48
What Will You See After an Airbag Inflates?....1-54
When Should an Airbag Inflate?....................1-52
Where Are the Airbags?...............................1-51
Airbag Systems
Adding Equipment to Your Airbag-Equipped
Vehicle...................................................1-59
Airbag Off Switch........................................1-56
How Does an Airbag Restrain?......................1-54
Servicing Your Airbag-Equipped Vehicle..........1-59
What Makes an Airbag Inflate?......................1-53
Antenna, Fixed Mast.......................................3-58Antilock Brake System (ABS)............................. 4-5
Antilock Brake, System Warning Light................3-34
Antilock Brakes, Trailer System Warning Light.....3-34
Appearance Care
Aluminum or Chrome-Plated Wheels..............5-98
Care of Safety Belts....................................5-96
Chemical Paint Spotting..............................5-100
Cleaning Exterior Lamps/Lenses....................5-97
Fabric/Carpet..............................................5-95
Finish Care.................................................5-97
Finish Damage............................................5-99
Instrument Panel, Vinyl, and Other Plastic
Surfaces.................................................5-96
Interior Cleaning..........................................5-94
Sheet Metal Damage...................................5-99
Tires..........................................................5-99
Underbody Maintenance.............................5-100
Vehicle Care/Appearance Materials...............5-100
Washing Your Vehicle...................................5-97
Weatherstrips..............................................5-96
Windshield and Wiper Blades........................5-98
Ashtray.........................................................3-20
Audio System.................................................3-47
Chime Level Adjustment...............................3-58
Fixed Mast Antenna.....................................3-58
Radio Reception..........................................3-58
Setting the Clock.........................................3-48
Theft-Deterrent Feature................................3-57
1

Cleaning
Aluminum or Chrome-Plated Wheels..............5-98
Exterior Lamps/Lenses.................................5-97
Fabric/Carpet..............................................5-95
Finish Care.................................................5-97
Instrument Panel, Vinyl, and Other Plastic
Surfaces.................................................5-96
Interior.......................................................5-94
Tires..........................................................5-99
Underbody Maintenance.............................5-100
Washing Your Vehicle...................................5-97
Weatherstrips..............................................5-96
Windshield and Wiper Blades........................5-98
Climate Control System...................................3-20
Outlet Adjustment........................................3-23
Rear Heating System...................................3-24
Clock, Setting.................................................3-48
Collision Damage Repair................................... 7-6
Control of a Vehicle.......................................... 4-3
Coolant
Engine Temperature Gage............................3-35
Heater, Engine............................................2-25
Low Warning Light.......................................3-35
Surge Tank Pressure Cap.............................5-47
Cooling System..............................................5-50
Cruise Control................................................3-10
Customer Assistance Information
Customer Assistance for Text
Telephone (TTY) Users............................... 7-3
Customer Assistance Offices........................... 7-4Customer Assistance Information (cont.)
Customer Satisfaction Procedure..................... 7-2
GM Mobility Reimbursement Program............... 7-5
Reporting Safety Defects to General Motors...... 7-9
Reporting Safety Defects to the Canadian
Government.............................................. 7-9
Reporting Safety Defects to the United
States Government.................................... 7-9
Roadside Assistance Program......................... 7-5
Service Publications Ordering Information........7-10
D
Daytime Running Lamps..................................3-15
Daytime Running Lamps Indicator Light.............3-41
Defensive Driving............................................. 4-2
Diesel
Running Out of Fuel....................................2-50
Diesel Engine.................................................2-26
Engine Alarm and Automatic Shutdown...........2-18
Exhaust Restrictor.......................................2-22
Fuel............................................................ 5-9
High Idle System.........................................2-20
Starting......................................................2-14
Diesel Particulate Filter....................................2-46
Diesel Particulate Filter Warning Light................3-45
Differential Lock Control, Rear Axle..................... 4-7
Differential Lock Indicator Light.........................3-40
Doing Your Own Service Work........................... 5-6
3

Dome Lamps.................................................3-16
Door
Locks.......................................................... 2-6
Power Door Locks......................................... 2-7
Driving
At Night.....................................................4-13
Defensive..................................................... 4-2
Drunken....................................................... 4-3
Highway Hypnosis.......................................4-15
Hill and Mountain Roads..............................4-15
In Rain and on Wet Roads...........................4-14
Rocking Your Vehicle to Get it Out.................4-20
Tow Hooks.................................................4-20
Winter........................................................4-16
Dual Tire Operation.........................................5-84
E
EDR .............................................................7-11
Electrical System
Add-On Equipment.....................................5-102
Fuses and Circuit Breakers.........................5-103
Fusible Links.............................................5-103
Headlamp Wiring.......................................5-102
Instrument Panel Fuse Block.......................5-103
Power Windows and Other Power Options....5-103
Underhood Fuse Block...............................5-106
Windshield Wiper Fuses.............................5-102Engine
Air Cleaner/Filter.........................................5-39
Alarm and Automatic Shutdown.....................2-18
Change Engine Oil Light...............................3-38
Check and Service Engine Soon Light............3-36
Checks Before Operating..............................2-23
Coolant......................................................5-44
Coolant Heater............................................2-25
Coolant Temperature Gage...........................3-35
Diesel Engine Exhaust Brake........................2-26
Drive Belt Routing......................................5-117
Exhaust.....................................................2-45
Exhaust Restrictor.......................................2-22
Fan Breakage............................................... 5-6
Fan Noise..................................................5-54
High Idle System.........................................2-20
Oil ....................................5-23, 5-24, 5-28, 5-32
Oil Life System...........................5-36, 5-37, 5-39
Overheating................................................5-48
Reduced Power Light...................................3-41
Shutdown Warning Light...............................3-39
Speed Limiter.............................................3-27
Starter Over-Crank Protection........................2-12
Starting Diesel............................................2-14
Starting the Gasoline...................................2-12
Engine Overspeed Warning Light......................3-39
Entry Lighting.................................................3-17
Event Data Recorders.....................................7-11
4