
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

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

Roadside Assistance Program
GM Medium Duty Truck’s Roadside Assistance
provides stranded owners with towing service
for disabled vehicles.
This service combines the efforts of trained
telephone representatives with a network of
GM Medium Duty Truck’s dealer services.
Just dial GM Medium Duty Truck Roadside
Assistance at1-800-862-4389to reach a qualified
representative who can assist you in a repair or
arrange a tow. Other recommended services
can also be arranged for situations such as
retrieving locked in keys, changing a tire, or
delivering gasoline, at a charge to the customer.
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. Should you
have any questions about Roadside Assistance,
call the GM Medium Duty Truck Roadside
Assistance Center or contact your dealer.
Canadian Roadside Assistance
In Canada, Medium Duty trucks are not eligible
for Roadside Assistance services. However,
owners/operators who contact Roadside
Assistance by calling1-800-268-6800may have
a tow arranged for them at the owner/operator
expense.
If a Medium Duty truck is towed to the nearest
General Motors dealership and the towing
was necessary due to failure of a warranted part,
the dealer will accept the towing charges and
submit them as part of the warranty claim.
408

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

A
Accessory Power Outlet(s).......................... 156
Adding a Snow Plow or Similar
Equipment................................................ 240
Adding Equipment to Your Airbag-Equipped
Vehicle....................................................... 81
Additives, Fuel............................................ 252
Add-On Electrical Equipment....................... 340
Air Cleaner/Filter, Engine............................. 280
Air Conditioning........................................... 157
Air Conditioning System.............................. 320
Air Pressure Gage...................................... 183
Air Shift Control........................................... 114
Air Suspension............................................ 129
Air Suspension Seats.................................... 13
Airbag
Off Light.................................................. 166
Readiness Light....................................... 165
Airbag Sensing and Diagnostic
Module (SDM).......................................... 409
Airbag System............................................... 68
Adding Equipment to Your
Airbag-Equipped Vehicle......................... 81
Airbag Off Switch....................................... 76
How Does an Airbag Restrain?.................. 73
Servicing Your Airbag-Equipped Vehicle..... 80Airbag System (cont.)
What Makes an Airbag Inflate?.................. 73
What Will You See After an Airbag
Inflates?................................................. 74
When Should an Airbag Inflate?................. 72
Where Are the Airbags?............................. 70
AM-FM Radio.............................................. 186
Antenna, Fixed Mast................................... 204
Anti-Lock Brake System (ABS).................... 212
Anti-Lock Brake, System Warning Light....... 172
Anti-Lock Brakes, Trailer System
Warning Light........................................... 172
Appearance Care
Aluminum or Chrome-Plated Wheels........ 337
Care of Safety Belts................................ 334
Chemical Paint Spotting........................... 338
Cleaning Exterior Lamps/Lenses.............. 335
Cleaning the Inside of Your Vehicle.......... 331
Fabric/Carpet........................................... 333
Finish Care.............................................. 335
Finish Damage......................................... 338
Instrument Panel, Vinyl, and Other
Plastic Surfaces.................................... 334
Sheet Metal Damage............................... 337
Tires........................................................ 337
Underbody Maintenance........................... 338
Vehicle Care/Appearance Materials.......... 339
417

Appearance Care (cont.)
Washing Your Vehicle.............................. 335
Weatherstrips........................................... 334
Windshield and Wiper Blades................... 336
Ashtray(s).................................................... 157
Audio System(s).......................................... 184
AM-FM Radio.......................................... 186
Care of Your Cassette Tape Player.......... 202
Care of Your CD Player........................... 204
Care of Your CDs.................................... 203
Chime Level Adjustment........................... 204
Fixed Mast Antenna................................. 204
Radio with Cassette................................. 189
Radio with CD......................................... 195
Setting the Time...................................... 185
Theft-Deterrent Feature............................ 201
Understanding Radio Reception............... 201
Automatic Ether Injection System................ 318
Automatic Transmission
Fluid........................................................ 282
Operation................................................. 115
Axle, Two-Speed Rear Axle Electric Shift
Control..................................................... 113B
Battery........................................................ 304
Bench Seat, Split.......................................... 13
Brake
Anti-Lock Brake System (ABS)................. 212
Diesel Engine Exhaust............................. 112
Emergencies............................................ 213
Exhaust Indicator Light............................. 178
Hydraulic Systems................................... 211
Parking...........................................125, 126
System Warning Light.............................. 169
Trailer Hand Control Valve....................... 214
Brakes........................................................ 297
Parking Brake Burnish Procedure............. 128
Braking....................................................... 210
Braking in Emergencies............................... 213
Break-In, New Vehicle................................... 95
Bucket Seats.................................................. 9
Bulb Replacement....................................... 315
C
California Proposition 65 Warning................ 248
Canadian Owners........................................... 3
Capacities and Specifications...................... 347
Carbon Monoxide...............................131, 231
418

Customer Assistance Information
Customer Assistance for Text Telephone
(TTY) Users.......................................... 406
Customer Assistance Offices.................... 406
Customer Satisfaction Procedure.............. 404
GM Mobility Reimbursement Program...... 407
Reporting Safety Defects to
General Motors..................................... 415
Reporting Safety Defects to the
Canadian Government.......................... 414
Reporting Safety Defects to the
United States Government.................... 414
Roadside Assistance Program.................. 408
Service Publications Ordering
Information........................................... 415
D
Daytime Running Lamps............................. 151
Daytime Running Lamps Indicator Light....... 179
Defensive Driving........................................ 206
Diesel Engine
Engine Alarm and Automatic Shutdown.... 104
Exhaust Brake......................................... 112
Exhaust Restrictor.................................... 108Diesel Engine (cont.)
Fuel......................................................... 253
High Idle System..................................... 106
Starting.................................................... 100
Differential Lock Control, Rear Axle............. 215
Differential Lock Indicator Light.................... 178
Doing Your Own Service Work.................... 249
Dome Lamps............................................... 153
Door
Locks......................................................... 91
Power Door Locks..................................... 92
Driver
Position, Safety Belt................................... 26
Driving
At Night................................................... 223
City.......................................................... 227
Defensive................................................. 206
Drunken................................................... 207
Freeway................................................... 228
Hill and Mountain Roads.......................... 230
In Rain and on Wet Roads...................... 224
Rocking Your Vehicle to Get it Out.......... 236
Tow Hooks............................................... 237
Winter...................................................... 231
Dual Tire Operation..................................... 323
420

E
Electrical System
Add-On Equipment................................... 340
Fuses and Circuit Breakers...................... 341
Fusible Links............................................ 341
Headlamp Wiring..................................... 341
Instrument Panel Fuse Block................... 342
Power Windows and Other Power
Options................................................. 341
Underhood Fuse Block............................. 344
Windshield Wiper Fuses........................... 341
Engine
Air Cleaner/Filter...................................... 280
Alarm and Automatic Shutdown................ 104
Battery..................................................... 304
Change Engine Oil Light.......................... 176
Check and Service Engine Soon Light..... 174
Checks Before Operating......................... 109
Coolant...........................................284, 287
Coolant Heater......................................... 111
Coolant Temperature Gage...................... 173
Diesel Engine Exhaust Brake................... 112
Drive Belt Routing.................................... 355
Exhaust................................................... 131
Exhaust Restrictor.................................... 108
Fan Breakage.......................................... 250Engine (cont.)
Fan Noise................................................ 294
High Idle System..................................... 106
Oil ...................................................268, 272
Oil Life System.......................276, 278, 279
Overheating............................................. 288
Overspeed Warning Light......................... 177
Reduced Power Light............................... 179
Shutdown Warning Light.......................... 177
Speed Limiter.......................................... 164
Starter Over-Crank Protection.................... 97
Starting Your Diesel................................. 100
Starting Your Gasoline............................... 97
Entry Lighting.............................................. 154
Event Data Recorders (EDR)...................... 409
Exhaust Brake Indicator Light...................... 178
Exhaust Restrictor....................................... 108
Extender, Safety Belt..................................... 41
Exterior Lamps............................................ 150
F
Filter
Engine Air Cleaner................................... 280
Filter Minder Gage...................................... 182
Finish Damage............................................ 338
Fixed Mast Antenna.................................... 204
421