engine GMC C-SERIES 1999 Owner's Guide

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2-55
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.
Safety Belt Reminder Light (Option)
When the key is turned to
RUN or START, a light will
come on for about eight
seconds to remind people
to fasten their safety belts.
Safety Belt Reminder Tone (Option)
When the key is turned to RUN or START, a tone will
sound for about eight seconds to remind people to fasten
their safety belts.
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2-56 Charging System Indicator Light
CAUTION:
If your vehicle has an electric/hydraulic parking
brake, do not drive if the charging system light is
on. If the battery drains too much, the parking
brake can suddenly come on and stop the vehicle.
This can cause severe injury to you and others.
The charging system light is
located in the center of the
instrument cluster just
above the odometer.
It should come on briefly when you turn on the ignition,
before the engine is running, as a check to show that it
is working.If it stays on, or comes on while you are driving, have it
checked right away. You could have a loose generator
drive belt or some other problem.
Driving while this light is on could drain your battery. If
you must drive a short distance with the light on, turn
off your radio and other accessories.
Sustained driving with a generator failure could result in
a lack of back
-up braking if the engine quits or the
power steering pump should fail.
Voltmeter
When your engine is
running, the voltmeter gage,
at the lower left of the
instrument cluster, shows
the charging system voltage.
Readings in either warning zone indicate a possible
problem in the electrical system.
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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.
Do Not Shift Warning Light
If your vehicle has the
Allison MD automatic
transmission, certain
transmission malfunctions
will turn this light on.If this light comes on while you are driving, do not use
the transmission shift control. Using the transmission
shift control will result in the loss of 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 the DO NOT SHIFT warning light comes on
while you are driving, it is a warning that making
a transmission ªrangeº change could leave you
stranded. The vehicle may not continue to move
if you change gears with the transmission shift
control. The transmission can't operate in all
gears because something is wrong. Leave the shift
control alone and drive directly to a GM dealer
for service. If you can't go in for service
immediately, have the vehicle towed.
Brake System Warning Light
Your vehicle has either hydraulic or air brakes. Each
system has different warning lights.
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Hydraulic Brake System Warning Lights
Vehicles with hydraulic systems have two brake system
warning lights on the instrument panel.
If the PRIMARY 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
primary hydraulic brakes.
When it comes on, you will also hear a warning tone.
The PRIMARY BRAKE warning light may come on,
and the warning tone may sound, when you're turning
and braking at the same time. This is normal. See
ªHydraulic Brake Systemsº in the Index.
If the AUX BRAKE
warning light comes on, it
means that there is
something wrong in the
auxiliary brake system.
When this light comes on, you will also hear a warning tone.Both of these lights should come on briefly every time
you start the engine. If they don't come on then, have
them fixed so they will be ready to warn you if there's a
problem. If one or both of these warning lights stay on
after you start the engine, there could be a brake
problem. Have your brake system inspected right away.
If one or both of these lights come on and stay on while
you are driving, pull off the road and stop carefully. You
may notice that the pedal is harder to push. Or, the pedal
may go closer to the floor. It may take longer to stop.
If either light is still on, have the vehicle towed for
service. (See ªTowing Your Vehicleº in the Index.)
See ªHydraulic Brake Systemsº in the Index for
more information.
CAUTION:
Your brake system may not be working properly
if a brake system warning light is on. Driving
with either of the brake system warning lights on
can lead to an accident. If either light is still on
after you've pulled off the road and stopped
carefully, have the vehicle towed for service.
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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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2-60 Apply Park Brake Warning Light (Option)
This light warns the driver
that the ignition has been
turned off without applying
the parking brake. The
warning light should come
on, as a check, when you
start the engine.
When it comes on, you will also hear a warning tone.
Leaving the vehicle in this condition could result in your
vehicle moving and will discharge the battery.
Parking Brake Warning Light
This light turns on as a
check when the engine is
first started and any time the
system needs adjustment or
there is a malfunction in the
electric/hydraulic parking
brake system.
When the SERVICE PARK BRAKE light comes on,
you will also hear a warning tone. If this light comes on,
have the system repaired immediately.
CAUTION:
If the SERVICE PARK BRAKE warning light
comes on and the warning tone sounds, your
vehicle can stop suddenly and without further
warning. You or others could be injured. If the
SERVICE PARK BRAKE warning light and the
warning tone come on, pull over to the side of the
road and apply the parking brake immediately.
Parking Brake Indicator Light
Vehicles with hydraulic or
air brakes have a parking
brake indicator 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 doesn't
release fully.
This light should also come on when you turn the
ignition key to START. If it doesn't come on then, have
it fixed so it will be ready to remind you if the parking
brake is applied or hasn't released fully.
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2-61 Anti-Lock Brake System Warning Light
(Option)
With the anti-lock brake
system, this light will come
on when you start your
engine and it may stay on
for several seconds.
That's normal.
If the light stays on, or comes on when you're driving,
your vehicle needs service. If the PRIMARY BRAKE or
LOW AIR warning light isn't on, you still have brakes,
but you don't have the anti
-lock brake feature. If the
PRIMARY BRAKE and/or LOW AIR warning light is
on, you don't have anti
-lock brakes and there's a
problem with your regular brakes. See ªBrake System
Warning Lightº earlier in this section.
The anti
-lock brake system warning light should come
on briefly when you turn the ignition key to RUN. If the
light doesn't come on then, have it fixed so it will be
ready to warn you if there is a problem.
Engine Coolant Temperature Gage
Gasoline Engine Diesel Engine
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.
See ªEngine Overheatingº in the Index. If you have a
Caterpillar

diesel engine, also see your Caterpillar

Operation & Maintenance Manual.
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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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