instrument panel GMC C-SERIES 1999 Owner's Manual

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2-59
Air Brake System Warning Light
Vehicles with air brake systems have one 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 to 70 psi
(410 to 480 kPa).When this warning light comes on, you will also hear a
warning tone. If the warning light and tone come on
while you are driving, you should drive only as far as
the nearest point of safety and then stop the vehicle.
Here's a very important thing for you to know:
CAUTION:
If the LOW AIR 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 40 to 45 psi (275 to 310 kPa).
You or others could be injured. If the LOW AIR
warning light comes on and the warning tone
sounds, stop as soon as you can. You won't
know how quickly the system is losing pressure,
so be aware that the parking brake may come
on suddenly.
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2-62 Low Coolant Warning Light
You have a LOW
COOLANT warning light.
If this light comes on,
your 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 at
five beats per second for 10 seconds. See ªEngine
Coolantº in the Index and have your vehicle serviced as
soon as you can.
This light may also come on if your vehicle is equipped
with the optional automatic engine shutdown system and
engine shutdown has begun. SeeªEngine Automatic
Shutdownº in the Index.
Manual Fast Idle Indicator Light
(If Equipped)
If your vehicle is equipped
with an electronically
controlled diesel engine or
gasoline engine, you may
have this indicator light. It
is located next to the FAST
IDLE switch on the lower,
driver's side of the
instrument panel.
This light will illuminate whenever the manual FAST
IDLE feature is engaged. For more details about this
system, see ªFast Idle Systemº in the Index.
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2-63 Intake Heater Indicator Light
(Diesel Engines)
This light on the instrument
panel will come on when
the intake heater is on and
the ignition key is in ON.
Since the light is illuminated whenever the intake heater
is activated, it is normal for the light to cycle on and off
as the heater cycles during engine warm
-up. See
ªEngine Startingº in your Caterpillar
Operation &
Maintenance Manual for more information.
Diff Lock Indicator Light (If Equipped)
This light on the instrument
panel is on when the
inter
-axle differential lock
system is in use.
The light will come on momentarily during starting.
If the light fails to come on, have it repaired as soon as
possible so you will be aware when the lock system is
in use.
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2-64 Service Trans Filter Indicator Light
(If Equipped)
If your vehicle has this
light, you'll find it
below the cluster on the
instrument panel.
It monitors the transmission fluid filter. If it ever
goes on, it means your transmission filter is dirty and
requires replacement.
Malfunction Indicator Lamp
(Check Engine Light)
If your vehicle is equipped
with either a gasoline
engine or an electronically
controlled diesel engine,
you will have this light.
If this light comes on or flashes while you are driving,
two things may happen.
First, you won't notice any difference in engine
performance, but your tail pipe emissions may increase.
Second, your engine may not run properly or may stall
without warning. If either of these things happen, drive
or tow your vehicle to your dealer for service.
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2-67 Daytime Running Lamps (DRL)
Indicator Light
This light is located on the
upper cluster portion of the
instrument panel. It goes on
whenever the Daytime
Running Lamps are on. See
ªDaytime Running Lampsº
in the Index.
When it begins to get dark, the DRL indicator light is a
reminder to turn on your headlamps.
Check Gages Indicator Light (If Equipped)
This light will come on as
you're starting the engine,
just as a check.
If it ever comes on and stays on while you are driving,
however, it means that either your engine coolant
temperature gage or your engine oil pressure gage may
be showing a reading in the warning zone.
When the CHECK GAGES light comes on, you will
also hear a warning tone. The tone and the light will stay
activated until the problem is corrected.
This light may also come on if your vehicle is equipped
with the optional automatic engine shutdown system and
engine shutdown has begun. See ªEngine Automatic
Shutdownº in the Index.
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2-69 Transmission Temperature Gage
(If Equipped)
If you have an automatic
transmission and this gage,
it is to the right of the dash
mounted shift lever, just to
the right of your
floor
-mounted shift lever or
on the lower portion of the
instrument panel to the right
of the steering wheel.
When your ignition is on, the gage shows the
temperature of the transmission oil. A reading in the
warning zone 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 when the transmission temperature
gage is in the warning zone, you can badly
damage the transmission.
Air Pressure Gage (If Equipped)
If your vehicle has air
brakes, this gage at the
center of your instrument
cluster shows the air
pressure for both your front
and rear brake systems.
If the needle on the gage indicates that the air pressure is
below 60 psi (415 kPa), the LOW AIR warning light
will come on. An alarm will also sound if this happens.
The yellow pointer shows the pressure available for the
front system, while the green pointer shows pressure for
the rear. There should be no more than 4 psi (28 kPa)
difference showing between the systems.
Don't drive until both pointers are showing at least
120 psi (830 kPa), so you'll have enough air if you need
to apply your brakes.
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2-70 Filterminder Gage (Diesel Engine)
This optional gage is in the
lower center of the
instrument panel. It
monitors the engine
air filter.
As the filter gets dirty, the yellow indicator will begin to
rise. When it reaches 25 inches of vacuum on the scale,
the filter should be replaced.
After replacing the filter, reset the gage by pressing in
the yellow reset pin at the bottom of the gage.
If you have a diesel engine, also see your Caterpillar


Operation & Maintenance Manual.
Hourmeter Gage (If Equipped)
If your vehicle has this
gage, it will be to the lower
left of the steering column,
mounted on a bracket either
above or below the fuse
block. It shows the total
engine operating time.
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3-2
Comfort Controls
Standard Comfort Controls
If your vehicle does not have air conditioning, this is
what your comfort controls will look like.
Function Lever
The top lever can be moved to three different heating
functions. If you place the lever between positions, it
will send air out both vents.
VENT: The air comes out at the vents on your
instrument panel and at your front side windows.
HEATER: Heated air comes out near the floor.
This is the best setting for cold weather.
DEFOG: This setting operates the defogger.
Heated air comes out near the windshield. Use this when
fog or ice is on the windshield.
Temperature Lever
The bottom lever lets you select the temperature of the
air flowing into your vehicle. Move the lever to the plus
symbol for warmer air. Move the lever to the minus
symbol for cooler air.
If your engine is equipped with an engine coolant heater,
you can use it during initial start
-up in cold weather
(20
F (
-8
C) or lower) to help heat the passenger
compartment faster. See ªEngine Coolant Heaterº in
the Index.
Fan Knob
The fan knob has four positions. To increase airflow,
turn the knob toward the plus symbol. To decrease
airflow, turn it toward the minus symbol.
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3-4
Left Blend Button
The airflow can be blended between the two positions.
To blend between the positions, press the side of the
button showing the area where you would like more
airflow. The system will automatically begin to blend
toward the position chosen. To stop the system between
positions, just press the same side of the button again.
VENT: Press the top of the button and all of the
airflow will come through the instrument panel vents.
HEATER: Press the bottom of this button and all
of the airflow will come through the floor outlet.
Right Blend Button
The airflow can be blended between the two positions.
To blend between positions, press the side of the button
showing the area where you would like more airflow.
The system will automatically begin to blend toward the
position chosen. To stop the system between positions,
just press the same side of the button again.
DEFOG: This setting operates the defogger. Air
comes out near the bottom of the windshield and at your
front side windows.
HEATER: Press the bottom of this button and
heated air comes out near the floor.A/C Button
Press the A/C button to turn your air conditioner on and
off. The A/C symbol will light on your display, and air
will come out of your instrument panel vents. The fan
will automatically be set on LOW.
MAX Button
If you press the MAX button, the air in your vehicle will
be recirculated. With the air conditioner on, MAX will
give you maximum cooling. It can also be used in all
modes to help keep dust out of your vehicle. When
MAX is selected, REC will light on the display.
Fan Control Button
This button is in the upper passenger's side corner of
your system control panel. The fan has four settings:
low, medium low, medium high and high. Press the top
of the button with the plus symbol to increase airflow.
Press the bottom of the button with the minus symbol to
decrease airflow. The setting you select is shown on
your display as LOW, MED, HI or OFF.
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3-6 Defogging
Use DEFOG, along with the HEATER setting, when
there is fog or ice on the windshield. This will direct
airflow toward the windshield and front side windows.
Set the temperature selector toward H and the fan
control at a comfortable level. When the windshield is
clear, use the temperature selector bar and the fan
control button to maintain a comfortable
temperature level.
Ventilation System
Air comes into your vehicle in one of two ways: power air
or ram air. Power air means bringing outside air into the
cab through the air intake, using the blower fan. Fresh air
can be drawn in when the vehicle is stationary or moving
at low speed. Air comes in through four vents in the
instrument panel and is exhausted through the vents and
pressure relief valves in the doors and door pillars. Power
ventilation means an increased supply of fresh air is
brought into the cab interior without having to open the
windows, especially during inclement weather.
Ram air is forced into the cab through the air intake in
the cowl by the vehicle's forward motion. This air is
controlled by two vent air handles under the instrument
panel. Air is directed through the ventilation ducts to the
floor. Ram air provides good airflow into the cab at
normal road speeds.
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