
Repeat this until help arrives but only when you feel
really uncomfortable from the cold. Moving about
to keep warm also helps.
If it takes some time for help to arrive, now and then
when you run the engine, push the accelerator
pedal slightly so the engine runs faster than the idle
speed. This keeps the battery charged to restart
the vehicle and to signal for help with the headlamps.
Do this as little as possible to save fuel.
If Your Vehicle is Stuck in Sand,
Mud, Ice, or Snow
Slowly and cautiously spin the wheels to free the
vehicle when stuck in sand, mud, ice, or snow. See
Rocking Your Vehicle to Get It Out on page 4-19.
If the vehicle has a traction system, it can often help to
free a stuck vehicle. Refer to the vehicle’s traction
system in the Index. If stuck too severely for the traction
system to free the vehicle, turn the traction system off
and use the rocking method.
{CAUTION:
If you let your vehicle’s tires spin at high speed,
they can explode, and you or others could be
injured. The vehicle can overheat, causing an
engine compartment fire or other damage. Spin the
wheels as little as possible and avoid going above
35 mph (55 km/h) as shown on the speedometer.
Rocking Your Vehicle to Get It Out
Turn the steering wheel left and right to clear the area
around the front wheels. For four-wheel-drive vehicles,
shift into 4HI. Turn off any traction system. Shift back and
forth between R (Reverse) and a forward gear, or with a
manual transmission, between 1 (First) or 2 (Second) and
R (Reverse), spinning the wheels as little as possible.
To prevent transmission wear, wait until the wheels stop
spinning before shifting gears. Release the accelerator
pedal while shifting, and press lightly on the accelerator
pedal when the transmission is in gear. Slowly spinning
the wheels in the forward and reverse directions causes a
rocking motion that could free the vehicle. If that does not
get the vehicle out after a few tries, it might need to be
towed out. If the vehicle does need to be towed out, see
Towing Your Vehicle on page 4-23.
4-19

Towing
Towing Your Vehicle
Consult your dealer/retailer or a professional towing
service to have the vehicle towed. They can provide the
right equipment and know-how to tow it without
damage. SeeRoadside Assistance Program on
page 7-5.
Releasing Air-Operated Parking Brakes
If the vehicle has air brakes, there could be a special
towing problem. If the vehicle has to be towed because
of a complete loss of air pressure from both systems,
the parking brakes will have automatically engaged.The tow operator can release the brakes manually by
using the following steps. Then the vehicle can be towed
with all wheels or only the rear wheels on the ground.
1. Block the wheels of the vehicle.
2. Remove the release stud and nut from the side of
the brake chamber. Some chambers have studs
which are visible at all times.
4-23

Trailer Connections
Heavy-Duty Trailer Wiring Package
The vehicle may be equipped with an eight-wire trailer
towing harness. This harness, with a seven-pin universal
heavy-duty trailer connector, is attached to a bracket
on the platform hitch.
The Center High-Mounted Stoplamp (CHMSL) wire is
tied next to the trailer wiring harness for use with a
trailer.
The eight-wire harness contains the following trailer
circuits:
•Yellow: Left Stop/Turn Signal
•Dark Green: Right Stop/Turn Signal
•Brown: Taillamps
•White: Ground
•Light Green: Back-up Lamps
•Light Blue: CHMSL
•Red: Battery Feed
•Dark Blue: Trailer Brake
Trailer Connections
(C7/C8 Models Only)
If the vehicle has these trailer connections, they are
located at the rear of the cab for a tractor and at the rear
of the chassis when towing a trailer. There will be an
air connection and an electrical connection.
Be sure that the couplings to the trailer are made
correctly.
Air Connections
If the trailer air line connections will not be connected to
another piece of equipment, be sure to replace their
protective caps.
Electrical Connections
This system is a seven-wire cable that will connect to
the trailer, supplying power to the trailer’s lighting
system. When not in use, it is stored in the trailer
air-hose storage bracket.
4-25

If you get the overheat warning with no sign of steam,
try this for a minute or so:
1. In heavy traffic, let the engine idle in N (Neutral)
while stopped. If it is safe to do so, pull off the
road, shift to P (Park) or N (Neutral) and let
the engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
3. If climbing a hill, downshift to raise engine and fan
speeds.
If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about 10 minutes.
If the warning does not come back on, you can drive
normally.
If the warning continues and you have not stopped, pull
over, stop, and park your vehicle right away.
If there is still no sign of steam, you can push down the
accelerator until the engine speed is about twice as
fast as normal idle speed for at least three minutes while
you are parked. If you still have the warning, turn off
the engine and get everyone out of the vehicle until it
cools down.
You may decide not to lift the hood but to get service
help right away.Engine Fan Noise
Your vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the clutch is not fully engaged. This improves
fuel economy and reduces fan noise. Under heavy
vehicle loading, trailer towing and/or high outside
temperatures, the fan speed increases when the clutch
engages. So you may hear an increase in fan noise.
This is normal and should not be mistaken as the
transmission slipping or making extra shifts. It is merely
the cooling system functioning properly. The fan will
slow down when additional cooling is not required and
the clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
Power Steering Fluid
SeeScheduled Maintenance on page 6-5to determine
when to check your power steering fluid.
5-49

GM Mobility Reimbursement
Program
This program, available to qualified applicants, can
reimburse you up to $1,000 of the cost of eligible
aftermarket adaptive equipment required for your vehicle,
such as hand controls or a wheelchair/scooter lift.
The offer is available for a very limited period of time
from the date of vehicle purchase/lease. For more
details, or to determine your vehicle’s eligibility, visit
gmmobility.com or call the GM Mobility Assistance
Center at 1-800-323-9935. Text telephone (TTY) users,
call 1-800-833-9935.
General Motors of Canada also has a Mobility Program.
Call 1-800-GM-DRIVE (463-7483) for details. TTY
users call 1-800-263-3830.
Roadside Assistance Program
GM Medium Duty truck’s Roadside Assistance provides
stranded owner/operators with towing service for
disabled GM Medium Duty trucks, during the base
and/or engine warranty period, to the nearest authorized
GM Medium Duty dealer. This service combines the
efforts of trained telephone representatives with a
network of GM Medium Duty truck services.
Call GM Medium Duty truck’s Roadside Assistance at
1-800-862-4389 to reach a qualified representative who
can assist you in arranging a tow to the nearest GM
Medium Duty truck dealer when your vehicle is disabled.
We also provide dealer information at no charge,
such as location of the nearest authorized GM Medium
Duty truck dealer and their hours of operation.
Our Roadside Assistance is available 24 hours a day,
7 days a week, 365 days a year which includes
weekends and holidays. Should you have questions
about GM Medium Duty truck Roadside Assistance, call
the GM Medium Duty Roadside Assistance Center or
contact your dealer.
Canadian Roadside Assistance
Whenever a Medium Duty truck owned and operated in
Canada becomes disabled, the owner/operator should
contact the Canadian Roadside Assistance Center
at 1-800-268-6800 for assistance.
7-5

Insuring Your Vehicle
Protect your investment in your GM vehicle with
comprehensive and collision insurance coverage. There
are significant differences in the quality of coverage
afforded by various insurance policy terms. Many
insurance policies provide reduced protection to your GM
vehicle by limiting compensation for damage repairs by
using aftermarket collision parts. Some insurance
companies will not specify aftermarket collision parts.
When purchasing insurance, we recommend that you
assure your vehicle will be repaired with GM original
equipment collision parts. If such insurance coverage is
not available from your current insurance carrier,
consider switching to another insurance carrier.
If your vehicle is leased, the leasing company may
require you to have insurance that assures repairs with
Genuine GM Original Equipment Manufacturer (OEM)
parts or Genuine Manufacturer replacement parts.
Read your lease carefully, as you may be charged at
the end of your lease for poor quality repairs.
If a Crash Occurs
Here is what to do if you are involved in a crash.
•Check to make sure that you are all right. If you
are uninjured, make sure that no one else in your
vehicle, or the other vehicle, is injured.
•If there has been an injury, call emergency services
for help. Do not leave the scene of a crash until all
matters have been taken care of. Move your vehicle
only if its position puts you in danger or you are
instructed to move it by a police officer.
•Give only the necessary and requested information
to police and other parties involved in the crash.
Do not discuss your personal condition, mental
frame of mind, or anything unrelated to the crash.
This will help guard against post-crash legal action.
•If you need roadside assistance, call GM Roadside
Assistance. SeeRoadside Assistance Program on
page 7-5for more information.
•If your vehicle cannot be driven, know where the
towing service will be taking it. Get a card from the
tow truck operator or write down the driver’s name,
the service’s name, and the phone number.
•Remove any valuables from your vehicle before it is
towed away. Make sure this includes your insurance
information and registration if you keep these items
in your vehicle.
7-7

Starting the Gasoline Engine............................2-12
Steering.......................................................... 4-9
Steering Wheel, Tilt Wheel................................. 3-6
Storage Areas................................................2-53
Center Console Storage Area........................2-53
Stuck in Sand, Mud, Ice, or Snow.....................4-19
Sun Visors...................................................... 2-9
Suspension, Air..............................................2-44
Switchbanks, Instrument Panel..........................3-18
T
Tachometer....................................................3-25
Theft-Deterrent, Radio.....................................3-57
Tilt Wheel........................................................ 3-6
Time, Setting..................................................3-48
Tires.............................................................5-76
Aluminum or Chrome-Plated Wheels,
Cleaning.................................................5-92
Buying New Tires........................................5-79
Cleaning....................................................5-92
Dual Tire Operation.....................................5-78
If a Tire Goes Flat.......................................5-85
Inflation - Tire Pressure................................5-77
Tightening the Wheel Nuts............................5-80Tires (cont.)
Wheel Alignment and Tire Balance.................5-80
Wheel Loading............................................5-78
Wheel Replacement.....................................5-84
When It Is Time for New Tires......................5-78
Tow Hooks.....................................................4-20
Towing
Your Vehicle...............................................4-23
Traction
Control System (TCS).................................... 4-8
Trailer
Connections................................................4-25
Trailer Brake Hand Control Valve........................ 4-6
Transmission
Fluid, Automatic...........................................5-42
Fluid, Manual..............................................5-42
Service Warning Light..................................3-30
Temperature Gage.......................................3-40
Transmission Operation, Automatic....................2-27
Transmission Operation, Manual........................2-28
Trip Odometer................................................3-25
Turn and Lane-Change Signals.......................... 3-7
Turn Signal/Multifunction Lever........................... 3-7
Two-Speed Rear Axle......................................2-36
11