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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. Waiting to do repairs
can be costly – and even dangerous.
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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 7.8L Diesel Engine shown, Canada, 6.6L Diesel and Gasoline Engine similar
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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 3-47.
Tachometer
This gage shows the safe operating range for the
engine speed in revolutions per minute (rpm).7.2L Caterpillar
®Diesel
Engine and 7.8L
DURAMAX
®Diesel
Engines
Gasoline and 6.6L
DURAMAX®Diesel
Engines
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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.
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.
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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 1-50.
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.
If the airbag readiness light stays on after you start the
vehicle or comes on when you are driving, your
airbag system may not work properly. Have your vehicle
serviced right away.The airbag readiness light should flash for a
few seconds when you turn the ignition key to RUN or
START. If the light doesn’t come on then, have it
fixed so it will be ready to warn you if there is a problem.
{CAUTION:
If the airbag readiness light stays on after you
start your vehicle, it means the airbag system
may not be working properly. The airbags in
your vehicle may not in ate in a crash, or they
could even in ate without a crash. To help
avoid injury to yourself or others, have your
vehicle serviced right away if the airbag
readiness light stays on after you start your
vehicle.
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Airbag Off Light
If your vehicle is equipped with an airbag off switch,
when you turn the right front passenger’s airbag off, this
light will come on and stay on to remind you that the
airbag has been turned off. This light will go off
when you turn the airbag on. SeeAirbag Off Switch on
page 1-58for more on this, including important safety
information.{CAUTION:
If the right front passenger’s airbag is turned
off for a person who is not in a risk group
identi ed by the national government, that
person will not have the extra protection of an
airbag. In a crash, the airbag will not be able to
in ate and help protect the person sitting
there. Do not turn off the passenger’s airbag
unless the person sitting there is in a risk
group. SeeAirbag Off Switch on page 1-58for
more on this, including important safety
information.
United States
Canada
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