Page 119 of 374

A. Air Outlets. SeeOutlet Adjustment on page 3-23.
B. Instrument Panel Cluster. SeeInstrument Panel
Cluster on page 3-25.
C. Shift Lever. SeeStarting the Gasoline Engine on
page 2-12orStarting the Diesel Engine on
page 2-14.
D. Air Brake Controls. SeeAir Brake on page 2-40.
E. Transfer Case Controls (If Equipped). See
“Automatic Transfer Case” underFour-Wheel Drive
on page 2-33. Air Filter Gage (If Equipped). See
Air Filter Restriction Indicator on page 3-43.
F. Auxiliary Gages. SeeWarning Lights, Gages, and
Indicators on page 3-24.
G. Exterior Lamp Control. SeeExterior Lamps on
page 3-14.H. Turn Signal/Multifunction Lever. SeeTurn
Signal/Multifunction Lever on page 3-7.
I. Hazard Warning Flashers Button. SeeHazard
Warning Flashers on page 3-6.
J. Audio System(s). SeeAudio System(s) on
page 3-44.
K. Climate Controls. SeeClimate Control System on
page 3-20.
L. Instrument Panel Switchbank. SeeInstrument Panel
Switchbank on page 3-18.
M. Airbag Off Switch. SeeAirbag Off Switch on
page 1-56.
N. Accessory Power Outlets. SeeAccessory Power
Outlets on page 3-19.
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Page 132 of 374
Instrument Panel SwitchbankThis switchbank is located in the center of the
instrument panel.
e(Marker Lamp Defeat Switch):SeeMarker Lamps
on page 3-16.
j(Manual High Idle Switch):See “Manual High
Idle System” underHigh Idle System
(Caterpillar
®Diesel/Gasoline Engine) on page 2-19.
i(Traction Control Switch):SeeTraction Control
System (TCS) on page 4-10.
f(Outside Heated Mirror Switch):SeeOutside
Heated Mirrors on page 2-46.
g(Power Take Off Switch):SeePower Take-Off
(PTO) on page 4-38.
h(Rear Air Suspension Dump Control Switch):Air
Suspension on page 2-42.
k(Rear Axle Shift Control Switch):SeeAir Shift
Control (Automatic Transmission) on page 2-27.
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Page 133 of 374

q(Exhaust Brake Switch):SeeDiesel Engine
Exhaust Brake on page 2-25.
l(Differential Lock Control Switch):SeeRear
Axle Differential Lock Contol on page 4-9.
c(Airbag On/Off Switch):SeeAirbag Off Switch on
page 1-56.
If your vehicle does not have some of the features
controlled by these switches, there will be a blank switch
marker in its place.
Accessory Power Outlets
With accessory power outlets, you can plug in auxiliary
electrical equipment such as a cellular telephone or
CB radio.
The accessory power outlet is located on the
passenger’s side of the instrument panel.
To use an outlet, pull the cover down. When not using
it, always cover the outlet with the protective cap.
This circuit is protected by a fuse and has a maximum
current level.Notice:Leaving electrical equipment on for
extended periods will drain the battery. Always turn
off electrical equipment when not in use and do
not plug in equipment that exceeds the maximum
amperage rating.
Certain electrical accessories may not be compatible
with the accessory power outlet and could result
in blown vehicle or adapter fuses. If you experience a
problem, see your dealer for additional information
on accessory power outlets.
Notice:Adding any electrical equipment to your
vehicle may damage it or keep other components
from working as they should. The repairs would not
be covered by your warranty. Do not use equipment
exceeding maximum amperage rating. Check
with your dealer before adding electrical equipment.
When adding electrical equipment, be sure to follow
the proper installation instructions included with
the equipment.
Notice:Improper use of the power outlet can cause
damage not covered by your warranty. Do not
hang any type of accessory or accessory bracket
from the plug because the power outlets are
designed for accessory power plugs only.
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Page 137 of 374

The rear window defogger will turn off several minutes
after the button is pressed. The defogger can also
be turned off by pressing the button again or by turning
off the engine.
Notice:Do not use anything sharp on the inside of
the rear window. If you do, you could cut or
damage the warming grid, and the repairs would not
be covered by your warranty. Do not attach a
temporary vehicle license, tape, a decal or anything
similar to the defogger grid.
Outlet Adjustment
Your vehicle has air outlets on the instrument panel that
allow you to adjust the direction and amount of airflow
inside the vehicle.
Move the lever on the outlet up or down to direct the
airflow. Increase or reduce the amount of airflow
by opening and closing the louvers. The outlets can be
moved side-to-side to direct the airflow.
Operation Tips
•
Keep the hood and front air inlets free of ice, snow,
or any other obstruction (such as leaves). The
heater and defroster will work far better, reducing
the chance of fogging the inside of your windows.
•Keep the air path under the front seats clear
of objects. This helps air to circulate throughout your
vehicle.
•Adding outside equipment to the front of your
vehicle, such as hood-air deflectors, may affect the
performance of the heating and air conditioning
system. Check with your dealer before adding
equipment to the outside of your vehicle.
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Page 138 of 374

Rear Heating System
If you have a crew cab
and your vehicle has a
rear heater, the
thumbwheel for this
feature is located on
the headliner.
To increase and decrease the flow of heated air to
the rear floor vents, turn the thumbwheel to the
desired fan speed. To turn the fan off, turn the
thumbwheel down.
Warning Lights, Gages, and
Indicators
This part describes the warning lights and gages that
may be on your vehicle. The pictures will help you
locate them.
Warning lights and gages can signal that something is
wrong before it becomes serious enough to cause
an expensive repair or replacement. Paying attention to
your warning lights and gages could also save you
or others from injury.
Warning lights come on when there may be or is a
problem with one of your vehicle’s functions. As you will
see in the details on the next few pages, some
warning lights come on briefly when you start the
engine just to let you know they’re working. If you are
familiar with this section, you should not be alarmed
when this happens.
Gages can indicate when there may be or is a problem
with one of your vehicle’s functions. Often gages
and warning lights work together to let you know when
there’s a problem with your vehicle.
When one of the warning lights comes on and stays on
when you are driving, or when one of the gages
shows there may be a problem, check the section that
tells you what to do about it. Please follow this
manual’s advice. Waiting to do repairs can be
costly – and even dangerous. So please get to know
your warning lights and gages. They’re a big help.
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Page 139 of 374
Instrument Panel Cluster
Your instrument panel cluster is designed to let you know at a glance how your vehicle is running. You’ll know how
fast your going, about how much fuel is left and many other things you’ll need to drive safely and economically.
United States Diesel Engine shown, Canada and Gasoline Engine similar
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Page 140 of 374

Speedometer and Odometer
Your speedometer lets you see your speed in both
miles per hour (mph) and kilometers per hour (km/h).
Your odometer shows how far your vehicle has
been driven, in either miles (used in the United States)
or kilometers (used in Canada).
Trip Odometer
The trip odometer can tell you how far your vehicle
has been driven since you last set the trip odometer
to zero.
While the engine is running, press the reset button,
located to the right of the trip odometer, to toggle
between the trip odometer and the regular odometer.
Holding the reset button for two seconds while the
engine is running and the trip odometer is displayed, will
reset it.
To display the odometer reading with the ignition off,
press the reset button.
The hourmeter gage is accessed through the trip
odometer, for more information seeHourmeter Gage on
page 3-44.
Tachometer
This gage shows the safe operating range for the
engine speed in revolutions per minute (rpm).
Engine Speed Limiter
All engines have electronic engine speed limiting. The
engine limited speeds range between
2,900 and 4,400 rpm depending on engine option
content.7.2L Caterpillar
®
Diesel Engine and
7.8L DURAMAX®
Diesel Engines
Gasoline and
6.6L DURAMAX®
Diesel Engines
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Page 141 of 374

Engine Road Speed Governor
This system controls maximum vehicle speed
automatically and reduces engine power until vehicle
speed gets down to maximum governed speed.
The default setting for C4500 and C5500 models up to
19,500 lbs GVWR is 80 to 85 mph (128 to 136 km/h).
Most other models have a default setting of 75 mph
(120 km/h), although some tire sizes and tread patterns
may limit maximum speed to 55 to 65 mph
(86 to 105 km/h). You may have a label on the headliner
of your vehicle with more information on your engine road
speed governor. See your GM dealer for assistance with
programming your engine limited speed.
Safety Belt Reminder Light
When the key is turned to RUN or START, a light will
come on for several seconds to remind people to fasten
their safety belts.
The safety belt light will
also come on and stay on
for several seconds.
Safety Belt Reminder Tone
If your vehicle has this feature, when you turn your key
to RUN or START, a tone will sound for several
seconds to remind people to fasten their safety belts.
Airbag Readiness Light
If your vehicle has airbags, there is an airbag readiness
light on the instrument panel, which shows the airbag
symbol. The system checks the airbag’s electrical
system for malfunctions. The light tells you if there is an
electrical problem. The system check includes the
airbag sensors, the airbag modules, the wiring, the
passenger airbag suppression circuit and the crash
sensing and diagnostic module. For more information on
the airbag system, seeAirbag System on page 1-48.
This light will come on
when you start your
vehicle, and it will flash for
a few seconds. Then the
light should go out. This
means the system is ready.
3-27