brakes GMC C-SERIES 1999 Owners Manual

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For example,
these symbols
are used on an
original battery:
CAUTION
POSSIBLE
INJURY
PROTECT
EYES BY
SHIELDING
CAUSTIC
BATTERY
ACID COULD
CAUSE
BURNS
AVOID
SPARKS OR
FLAMES
SPARK OR
FLAME
COULD
EXPLODE
BATTERY
These symbols
are important
for you and
your passengers
whenever your
vehicle is
driven:
DOOR LOCK
UNLOCK
FASTEN
SEAT
BELTS
POWER
WINDOW
AIR BAG
These symbols
have to do with
your lamps:
MASTER
LIGHTING
SWITCH
TURN
SIGNALS
PARKING
LAMPS
HAZARD
WARNING
FLASHER
DAYTIME
RUNNING
LAMPS
FOG LAMPS
These symbols
are on some of
your controls:
WINDSHIELD
WIPER
WINDSHIELD
WASHER
WINDSHIELD
DEFROSTER
REAR
WINDOW
DEFOGGER
VENTILATING
FAN
These symbols
are used on
warning and
indicator lights:
ENGINE
COOLANT
TEMP
BATTERY
CHARGING
SYSTEM
BRAKE
COOLANT
ENGINE OIL
PRESSURE
ANTI-LOCK
BRAKES
Here are some
other symbols
you may see:
FUSE
LIGHTER
HORN
SPEAKER
FUEL
Vehicle Symbols
These are some of the symbols you may find on your vehicle.
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2-13
The manual fast idle feature is activated by pressing the
switch on the instrument panel. When the switch is
pressed again, or any of the previous conditions are not
met, manual fast idle will be deactivated.
Manual fast idle can be used to set any desired idle
speed. To set a new temporary engine idle speed:
1. Make sure all of the previously described conditions
are met.
2. Press the accelerator pedal to the desired engine speed.
3. Momentarily press the manual FAST IDLE switch.
The temporary idle speed will be set. This new rpm
level will be remembered by the system until either the
ignition is turned to OFF or a new idle speed is set.
Radiator Shutters -- Caterpillar

(If Equipped)
Radiator shutters aid engine warm-up by blocking the
airflow through the radiator and charge the air cooler to
conserve heat in cold conditions.
The radiator shutters on your vehicle (if equipped)
operate automatically. When the ignition switch is in
RUN or START and the engine temperature is below
195F (90C), the shutters will close, blocking the flow
of air through the radiator and charge the air cooler.When the engine temperature reaches 195F (90C), the
shutters will open to the normal operating position.
Engine Checks Before Operating
When you've started your engine, let it run for 20 to
30 seconds before you put a load on the engine.
But don't leave the vehicle while the engine is running.
During this warm
-up period, check your warning lights
and gages:

If oil pressure doesn't begin to rise within 15 seconds
of starting, stop the engine and find the cause.

If the engine coolant temperature gage needle goes
into the hot area on the gage, stop the engine and
find the cause of the overheating.

If you have air brakes, the dual
-needle air pressure
gage should read at least 105 psi (720 kPa) for both
service systems before you try to move the vehicle.
When air pressure is below 60 psi (420 kPa), the
LOW AIR light will come on and you will hear a
tone alarm. If the pressure doesn't build up or drops
during warm
-up, stop the engine and find the cause
before you try to move the vehicle. Recommended
air pressure before actually driving away is
120 psi (830 kPa).
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2-16
4. Before starting the engine, be sure to unplug the cord.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature.
Above 32
F (0
C), the coolant heater is not required.
From 32
F to
-10
F (0
C to -23
C), keep the
coolant heater plugged in at least two hours. Below
-10
F (-23
C), keep the coolant heater plugged in for
a minimum of eight hours or overnight. It will not harm
either the coolant heater or the vehicle to leave the
coolant heater plugged in longer than the times stated.
Be sure to remove and store the cord before starting the
engine. See ªDiesel Fuel Requirements and Fuel
Systemº in the Index for information on what fuel to use
in cold weather.
Diesel Engine Exhaust Brake
The exhaust brake is available on vehicles equipped
with a diesel engine and air brakes (or an air
compressor). It is located in the exhaust system.
The switch is on the upper
right side of the instrument
panel and turns the exhaust
brake on and off.
The exhaust brake indicator light is on when the exhaust
brake is in use.
The exhaust brake is used to help slow the vehicle and
may assist the vehicle's foundation brakes. The use of the
exhaust brake will assist the braking of the vehicle and
prolong the life of the foundation brake lining material.
When using the exhaust brake, the proper gear range
selection is important. The exhaust brake will be most
effective if the gear range selected is the lowest possible
range that does not allow the engine rpm to go more than
200 rpm above rated (full load) rpm as shown on the
Engine Information Plate. (Do not exceed 2900 rpm.)
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2-24 Hydraulic Brakes
If your vehicle has hydraulic brakes, it has a parking
brake lever or an electric/hydraulic parking brake. The
lever is below the instrument panel to the left of the
steering column. The electric/hydraulic parking brake
knob is to the right of the steering column.
Your vehicle may also be equipped with an automatic
transmission which has a shift lever. This lever will have
a PARK (P) position on the shift indicator. When the
PARK (P) position is selected with the shift lever, the
parking brake is automatically applied.
Propshaft Brake Burnish Procedure
It is recommended that the propshaft-mounted parking
brake be burnished as part of the new vehicle break
-in.
The parking brake will work best after it has been
burnished following these instructions.
Make 10 stops, using the parking brake hand lever, from
20 mph (32 km/h) about 2 1/2 miles (4 km) apart.
Between stops, drive the vehicle at 20 mph (32 km/h).
Lever Operated Parking Brake
To apply the parking brake,
pull the lever all the way up.
The PARK BRAKE light
will come on when the
parking brake is applied.
Then shift the transmission
to NEUTRAL (N) or
PARK (P).
The vehicle must be stopped when applying the parking
brake, except while burnishing the parking brake linings
(see ªPropshaft Brake Burnish Procedureº in the Index).
You can easily adjust the parking brake by turning the
knob on the lever. Turning it clockwise makes the brake
grip more tightly. It will also make the lever seem harder
to pull up. Turning the knob counterclockwise makes the
parking brake apply less firmly. Adjust the parking
brake only when the lever is down (released).
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If your vehicle has air
brakes, you will have this
control. Pulling it out
applies the parking brake.
The PARK BRAKE light
will come on when the air
parking brake is applied.
Vehicles built for use as tractors or towing vehicles have
one or two more air brake controls. They look like this:To charge a trailer's air brake system:
1. Move your tractor into the proper position. Apply the
parking brake by pulling the yellow SYSTEM PARK
knob out.
2. Hook up the trailer air system properly.
3. Get into the tractor. Push and hold down the regular
brake pedal.
4. Push in both the yellow SYSTEM PARK and the red
TRAILER AIR SUPPLY knobs. This will charge
your trailer's air system.
If you have the blue TRACTOR PARKING knob,
pull it out to set the tractor brakes while the air system
is charging.
After a few minutes, the trailer system should be fully
charged. When it is, the air pressure gage will show
about 125 to 135 psi (862 to 931 kPa) and you may hear
the ªpop offº valve operate.
For driving with a trailer, the yellow, red and blue
(if equipped) knobs all must be pushed in. It's the same
when you're not pulling a trailer except that the red
TRAILER AIR SUPPLY knob must be out.
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CAUTION:
If you apply any one of the air brake parking
controls while the vehicle is moving, your rig will
stop suddenly. If you are not ready for this, you
or others could be injured. Don't apply any one
of these controls while you're driving, unless you
have to make an emergency stop.
If the air pressure drops below 60 to 70 psi (413 to
482 kPa), the PRIMARY BRAKE light will come on. If
the air pressure drops to 40 to 45 psi (275 to 309 kPa), the
yellow knob will automatically pop out and apply the
spring brakes. If you ever have a complete loss of air so
that your air brakes automatically apply, there is a way that
the tow operator can release the parking brakes to tow the
vehicle. See ªTowing Your Vehicleº in the Index.
CAUTION:
If your vehicle is left in gear, the engine can
start if the vehicle starts to roll. This can easily
happen if you have the diesel engine. Shift the
transmission into NEUTRAL (N) before you
leave the vehicle.
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2-36 Cruise Control (If Equipped)
With cruise control, you can
maintain a speed of about
30 mph (48 km/h) or more
without keeping your foot
on the accelerator. Cruise
control does not work at
speeds below about 30 mph
(48 km/h).
If you have an automatic transmission and you apply
your brakes, the cruise control will shut off.
If you have a manual transmission and you apply your
brakes or push the clutch pedal, the cruise control will
shut off.CAUTION:

Cruise control can be dangerous where you
can't drive safely at a steady speed. So,
don't use your cruise control on winding
roads or in heavy traffic.

Cruise control can be dangerous on
slippery roads. On such roads, fast changes
in tire traction can cause needless wheel
spinning, and you could lose control. Don't
use cruise control on slippery roads.
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Using Cruise Control on Hills
How well your cruise control will work on hills depends
upon your speed, load and the steepness of the hills.
When going up steep hills, you may want to step on the
accelerator pedal to maintain your speed. When going
downhill, you may have to brake or shift to a lower gear
to keep your speed down. Of course, applying the brake
or clutch takes you out of cruise control. Many drivers
find this to be too much trouble and don't use cruise
control on steep hills.
Ending Cruise Control
There are different ways to turn off the cruise control:

Step lightly on the brake pedal.

Push the clutch pedal, if you have a
manual transmission.

Move the cruise switch to OFF.
Erasing Speed Memory
When you turn off the ignition, your cruise control set
speed memory is erased.Trailer Brake Hand Control Valve
(Option)
If your vehicle has this feature, it is mounted on the
steering column.
This control lets you apply the trailer brakes without
applying the tractor brakes. You can apply the trailer
brakes a little or apply them all the way if you have to.
Use this control only when you're driving. Don't use it
for parking or to hold the rig on a hill.
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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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