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Voltmeter Gage
When your engine is
running, the voltmeter
gage shows the charging
system voltage.
Readings in either warning zone indicate a possible
problem in the electrical system.
Readings in the low warning zone may occur when a
large number of electrical accessories are operating in
the vehicle and the engine is left at an idle for an
extended period. This condition is normal since the
charging system may not be able to provide full power
at engine idle. As engine speeds are increased, this
condition should correct itself because higher engine
speeds allow the charging system to create maximum
power.
You can only drive a short time on the battery. Be sure
to shut off the radio, the fan or any unnecessary
accessories and have the system serviced.
Service Transmission Warning Light
If your vehicle has an Allison®automatic transmission,
certain transmission malfunctions will turn this light on.
This light is located with
the auxiliary warning lights
in the center of the
instrument panel.
If this light comes on while you are driving, do not use
the transmission shift control or you may lose forward
gears. The computer for the transmission senses
a problem and chooses a gear to stay in so that you
can drive the vehicle in that gear. You may not be able
to drive as fast or back up when this light is on.
Notice:If you continue driving your vehicle after the
transmission warning light comes on, you could
damage the transmission. While this light is on, the
transmission cannot operate in all gears. If you
attempt to shift gears, the vehicle may not continue
to move. Do not attempt to shift gears while the
transmission warning light is on. Instead, drive
directly to an authorized dealer for service. If you
cannot drive to a dealer immediately, have the
vehicle towed.
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Range Inhibit Warning Indicator
If your vehicle has an Allison 1000/2200/2300/
2500 series automatic transmission, a lighted bar
under the current gear selected will flash.
If your vehicle has an Allison 3000/3500 series automatic
transmission, the current gear selected on the pushbutton
display will flash.
The flashing bar or gear selection indicates that
transmission range shifts may not occur.
For detailed information on shift inhibit limitations, see
the Allison Automatic Transmission Operator’s Manual in
your vehicle for further information.
Brake System Warning Light
Your vehicle has either hydraulic or air brakes. Each
system has different warning lights.
Hydraulic Brake System Warning Lights
Vehicles with hydraulic brake systems have two brake
system warning lights on the instrument panel.
If the brake warning light
comes on, it means that the
fluid level in the master
cylinder reservoir is low or
there is another problem
with your hydraulic brakes.
When it comes on, you will also hear a warning tone.
This light should come on briefly when you turn the
ignition key to ON/RUN. If it does not come on, then have
it fixed so it will be ready to warn you if there is a problem.
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If the light comes on while driving, pull off the road and
stop carefully. The pedal might be harder to push or
might go the floor. It can take longer to stop. If the light
remains on, have the vehicle towed for service. See
Towing Your Vehicle on page 4-23for more information.
The brake warning light may come on, and the
warning tone may sound, when you are turning and
braking at the same time. This is normal. See “Hydraulic
Brake Systems” underBraking on page 4-4.
Parking Brake Warning Light
Your vehicle has a brake warning light. When the
ignition is on, this light will come on when you set your
parking brake. The light will stay on if your parking
brake does not release fully.
This light should also come on when you turn the
ignition key to START. If it does not come on then, have
it fixed so it will be ready to remind you if the parking
brake is applied or has not released fully.
Air Brake System Warning Light
Vehicles with air brake systems have a brake system
warning light on the instrument panel.
The low air warning light
should come on, as a
check, whenever you start
the engine.
However, it is designed to come on, and stay on, when
brake reservoir pressure has dropped below 60 psi
(410 kPa).
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When the warning light comes on while you are driving,
you should drive only as far as the nearest point of
safety and then stop the vehicle. Here is a very
important thing for you to know:
{CAUTION:
If the air brake system warning light comes on and
the warning tone sounds, the vehicle can stop
suddenly and without further warning. This is
because the parking brake will come on if the
pressure falls below 35 to 45 psi (240 to 310 kPa).
You or others could be injured. If the air brake
system warning light comes on and the warning
tone sounds, stop as soon as you can. You will
not know how quickly the system is losing
pressure, so be aware that the parking brake may
come on suddenly.
Antilock Brake System (ABS)
Warning Light
This light will come on
briefly when you start the
engine, then it will turn
off. This is normal.
If the light stays on, or comes on when you are driving,
your vehicle needs service. If the brake or low air warning
light is not on, you still have brakes, but you do not have
the antilock brake feature. If the brake and/or low air
warning light is on, you do not have antilock brakes and
there is a problem with your regular brakes. SeeBrake
System Warning Light on page 3-31andAntilock Brake
System (ABS) on page 4-5for more information.
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Trailer Antilock Brake System
Warning Light
If your vehicle is connected
to a trailer with antilock
brakes, this light should
come on briefly, as a
check, when you turn on
the ignition.
When this light comes on and stays on, it means there
is something wrong in the trailer Antilock Brake
System (ABS). Have the system repaired immediately.
If an ABS equipped trailer is not connected, this
light is not functional.
Engine Coolant Temperature Gage
This gage shows
the engine coolant
temperature. If the gage
pointer moves into the
red area, your engine
coolant might have
overheated and your
engine may be too hot.
You should pull off the road, stop your vehicle and turn
off the engine as soon as possible.
SeeEngine Overheating on page 5-48. If you have a
Caterpillar
®diesel engine, also see your Caterpillar®
Operation & Maintenance Manual.
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Low Coolant Warning Light
Your vehicle has a low
coolant warning light.
If this light comes on, the
system is low on coolant
and the engine may
overheat.
The warning light should come on briefly, as a check,
when you turn on the ignition.
When it comes on, you will also hear a warning tone for
10 seconds. SeeEngine Coolant (Caterpillar Diesel
Engines) on page 5-47and have your vehicle serviced
as soon as you can.
This light may also come on if your vehicle has the
automatic engine shutdown system and engine
shutdown has begun. SeeEngine Alarm and Automatic
Shutdown on page 2-18for more information.
Wait to Start Light
If your vehicle has the DURAMAX®6.6L diesel engine,
it will have glow plugs and an air intake heater. If your
vehicle has the Isuzu 6H diesel engine, it will have glow
plugs and an inlet heater. If your vehicle has a Caterpillar
engine, it will have an inlet heater.
The light in the center of the
instrument panel will come
on when the inlet heater or
glow plugs are on and the
ignition key is in ON/RUN.
Wait until the indicator light goes off before turning the
ignition key to START.
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Malfunction Indicator Lamp
Check Engine Light
A computer system called OBD II (On-Board
Diagnostics-Second Generation) monitors operation
of the fuel, ignition, and emission control systems.
It makes sure that emissions are at acceptable levels
for the life of the vehicle, helping to produce a cleaner
environment.
If this light comes on while
you are driving, two things
can happen.
First, you will not notice any difference in engine
performance, but the tail pipe emissions might increase.
Second, the engine might not run properly or could
stall without warning. If either of these things happen,
see your dealer/retailer for service.This light should come on when the ignition is on, but
the engine is not running, as a check to show it is
working. If it does not come on at all, have it repaired.
Notice:If the vehicle is continually driven with
this light on, after a while, the emission controls
might not work as well, the vehicle’s fuel economy
might not be as good, and the engine might not
run as smoothly. This could lead to costly repairs
that might not be covered by the vehicle warranty.
Notice:Modifications made to the engine,
transmission, exhaust, intake, or fuel system of the
vehicle or the replacement of the original tires
with other than those of the same Tire Performance
Criteria (TPC) can affect the vehicle’s emission
controls and can cause this light to come on.
Modifications to these systems could lead to costly
repairs not covered by the vehicle warranty. This
could also result in a failure to pass a required
Emission Inspection/Maintenance test. See
Accessories and Modifications on page 5-3.
If the check engine light comes on and stays on, while
the engine is running this indicates that there is an
OBDII problem and service is required.
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Engine Overspeed Warning Light
If your vehicle has this
light, it will come on if
your engine is operating
at too many revolutions per
minute (rpm).
It will also come on for a moment as a check when you
start your engine.
If it comes on when you’re driving, reduce your engine
speed immediately.
Engine Shutdown Warning Light
If your vehicle has the
engine shutdown feature,
this light will come on
when engine shutdown is
active.
SeeEngine Alarm and Automatic Shutdown on
page 2-18for more information.
Transmission Temperature Gage
If you have an automatic
transmission and this gage,
it is located above the
switchbank in the center of
the instrument panel.
When your ignition is on, the gage shows the
temperature of the transmission oil. A reading in the
warning zone, the red area beginning at 300°F (150°C),
means you must stop driving and check into the
cause. One possible cause is a low oil level in the
transmission.
Notice:If you drive your vehicle with the
transmission temperature gage above normal
operating range, you can damage the transmission.
This could lead to costly repairs that would not
be covered by your warranty. Do not drive your
vehicle while the transmission temperature gage
reading is above normal. See your dealer for service.
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