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GENERAL INFORMATION
WARNING: Exceeding these ratings
by overloading can cause component
failure resulting in property damage,
personal injury or death.
Fluid Temperature
If the operating temperature exceeds
250°F (121°C), the rate of axle lubrication
oxidation increases and shortens the life
of the lubricant and seals, requiring axle
lubrication changes to become more
frequent to preserve the axle. Do not
consistently run extreme pressure (EP)
lubricants above
250°F (121°C).
Axle Conversions WARNING:
When operating a
loaded vehicle, the driver must keep all
adjustable axles on the ground at all
times, supporting their share of the
vehicle ’s load. Failure to do so can
overload other axles, tires, wheels,
springs, steering components, brakes
and frames, resulting in early component
failure, loss of vehicle control, possible
property damage and personal injury.
We do not recommend, or approve,
performing axle conversions. However, we
understand that, on occasion, others install
aftermarket add-on axles on the truck
chassis that allow operator control for
weight transfer from other axles (such as
air lift axles). ELECTRONIC LOCKING
DIFFERENTIAL
(IF EQUIPPED)
Driver-Controlled Electronic
Locking Differential
Note: Never use the differential lock at
vehicle speeds above
25 mph (40 km/h).
Some drive axles have a driver-controlled
differential lock. The differential lock can
lock or unlock the differential when your
vehicle is moving or stopped. When you
require extra traction, the differential lock
provides full power to both wheels.
When you lock the differential, your
vehicle ’s turning radius increases
(under-steer).
Take care to avoid sudden accelerations
when both drive wheels are on a slippery
surface. WARNING:
Sudden acceleration
on slippery surfaces could cause the
wheels to spin, the vehicle to turn
sideways on a crowned road surface or
in a turn, possibly resulting in loss of
vehicle control and personal injury.
Activating the Electronic Locking
Differential
You can lock and unlock the differential
when your vehicle is moving at a constant
speed of less than 25 mph (40 km/h) and
while the wheels are not slipping. Do not
lock the differential when your vehicle is
traveling down steep grades and when
traction is minimal.
The differential lock and differential lock
light automatically disengage at speeds
above
25 mph (40 km/h). The differential
lock remains off until either you restart your
vehicle, or you turn the differential lock
switch off then back on.
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Servicing a Vehicle with an
Electronic Locking Differential
Turn the engine off and raise all drive
wheels of the locker differential axle to
prevent your vehicle from moving when
servicing the wheels, tires or brakes. Axles
equipped with a driver-controlled
differential deliver power to both wheels
even when only one wheel is on the ground.
WARNING: Failure to raise all drive
wheels with this type of differential could
cause the vehicle to move unexpectedly,
resulting in property damage, personal
injury or death.
2-SPEED REAR AXLE (IF EQUIPPED) WARNING: Never shift a
two-speed axle when descending a
steep grade as this may cause loss of
vehicle control and result in personal
injury.
Note: Do not shift between ranges when
the speed control is on.
A two-speed rear axle allows the driver to
select a low range for greater pulling power
and a high range for greater road speed
and fuel economy. You can also use these
ranges to provide extra steps between
transmission shifts when driving on steep
grades or fuel economy may be factors. Axle Shifting Note:
Do not shift the axle to LOW when
your vehicle is moving. Use LOW when you
drive a fully loaded vehicle on a severe grade
or in congested traffic. Use HIGH for all
normal driving conditions with a lightly
loaded or partially loaded vehicle.
Note: The axle is set to HIGH by default.
To shift the axle between HIGH and LOW
with the vehicle stopped, place the
transmission in position N, then press and
hold the button for two seconds.
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GENERAL INFORMATION
WARNING: Do not apply the brake
pedal and accelerator pedal
simultaneously. Applying both pedals
simultaneously for more than a few
seconds will limit engine performance,
which may result in difficulty maintaining
speed in traffic and could lead to serious
injury.
Note: Occasional brake noise is normal. If
a metal-to-metal, continuous grinding or
continuous squeal sound is present, the
brake linings may be worn-out. Have the
system checked as soon as possible. If your
vehicle has continuous vibration or shudder
in the steering wheel while braking, have it
checked by an authorized dealer.
All standard equipment brakes are
self-adjusting. Automatic adjustment,
when required, occurs whenever you apply
and release the brakes during forward or
reverse operation.
Know the required stopping distances for
all driving conditions you may encounter.
For longer brake lining life, take full
advantage of engine braking power when
coming to a stop.
Wet brakes result in reduced braking
efficiency. Gently press the brake pedal a
few times when driving from a car wash or
standing water to dry the brakes.
If the brakes do not grip well:
• Check brake adjustment.
• Check the brake linings for excessive
wear.
• Check the system air pressure on
vehicles with air brakes. •
Let the brakes cool if you have been
using them excessively, as in mountain
driving or after several fast, high-speed
stops.
• If you have been driving through deep
water, gently apply the brakes several
times while your vehicle is moving
slowly.
Brake Over Accelerator
In the event the accelerator pedal
becomes stuck or entrapped, apply steady
and firm pressure to the brake pedal to
slow the vehicle and reduce engine power.
If you experience this condition, apply the
brakes and bring your vehicle to a safe
stop. Move the transmission to park (P),
switch the engine off and apply the parking
brake. Inspect the accelerator pedal for
any interference. If none are found and the
condition persists, have your vehicle towed
to the nearest authorized dealer
Anti-lock Brake System
This system helps you maintain steering
control during emergency stops by keeping
the brakes from locking. This lamp momentarily
illuminates when you switch the
ignition on. If the light does not
illuminate during start up, remains on or
flashes, the system may be disabled. Have
the system checked by an authorized
dealer. If you connect a PLC trailer with
the ignition on, the trailer ABS
light also illuminates. If the light
fails to illuminate, if it remains on after you
start the vehicle or continues to flash, have
the system serviced immediately.
See
Warning Lamps and Indicators
(page 66).
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If the system is disabled, normal
braking is still effective. If the
brake warning lamp illuminates
when you release the parking brake, have
the system checked by an authorized
dealer. It also illuminates momentarily
when you switch the ignition on to confirm
the lamp is functional. If it does not
illuminate when you switch the ignition on,
or begins to flash at any time, have the
system checked by an authorized dealer.
HINTS ON DRIVING WITH
ANTI-LOCK BRAKES
The anti-lock brake system does not
eliminate the risks when:
• You drive too closely to the vehicle in
front of you.
• Your vehicle is hydroplaning.
• You take corners too fast.
• The road surface is poor.
Note: If the system activates, the brake
pedal could pulse and may travel further.
Maintain pressure on the brake pedal. You
may also hear a noise from the system. This
is normal.
PARKING BRAKE
Hydraulic Brakes (If Equipped) WARNING:
Always set the parking
brake and leave your vehicle with the
transmission in park (P). WARNING:
This control is for
parking only. Do not leave the vehicle
unattended after setting the parking
brake without placing the transmission
in park (P). We recommend using wheel
chocks for hilly or off-road
circumstances. WARNING:
Unexpected and
possibly sudden vehicle movement may
occur if you do not take these
precautions. WARNING:
If the parking brake is
fully released, but the brake warning
lamp remains illuminated, the brakes
may not be working properly. Have your
vehicle checked as soon as possible.
Apply the parking brake whenever the
vehicle is parked. To set the parking brake,
pull the handle up until it snaps into the
locked position.
When the parking brake is out of
adjustment, seek service immediately. The parking brake warning lamp
in the instrument cluster
illuminates, and remains
illuminated (when you switch on the
ignition), until you release the parking
brake. 137
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Push the palm release lever (A) on the
parking brake handle (B) and push down
as far as possible to release the brake.
Driving with the parking brake on causes
the brakes to wear out quickly and reduces
fuel economy.
We recommend you not use the parking
brake to stop a moving vehicle. However,
if the normal brakes fail, you can use the
parking brake to stop your vehicle in an
emergency. Since the parking brake only
applies retardation to the rear wheels, the
vehicle's stopping distance increases
greatly and the handling of your vehicle is
adversely affected.
Releasing Spring Manually
WARNING: Do not attempt to
disassemble the parking brake air
chamber under any circumstances as
this may cause serious injury. WARNING:
Block the wheels to
help prevent the vehicle from moving. WARNING:
Unexpected and
possibly sudden vehicle movement may
occur if you do not take these
precautions.
If you release hydraulic pressure from the
spring brake chamber, the power spring
applies the brake. If the hydraulic pressure
can be re-established, you must release
the spring brake in order to move your
vehicle. Air Brakes
(If Equipped) WARNING:
This control is for
parking only. Do not leave the vehicle
unattended after setting the parking
brake without placing the transmission
in park (P). We recommend using wheel
chocks for hilly or off-road
circumstances.
If the service brakes fail to operate while
your vehicle is moving, you can make an
emergency stop with the parking brake.
Since the parking brake only applies
stopping power to the rear wheels, your
vehicle ’s stopping distance greatly
increases and the handling of your vehicle
is adversely affected. Make repairs
immediately to an inoperative air brake
system circuit. Pull the yellow, dash-mounted parking
brake knob to apply the parking brake.
The parking brake light
illuminates and remains
illuminated (when you switch
the ignition to the on position) until you
release the parking brake.
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Releasing the Parking Brake
WARNING: When your vehicle is
stationary, keep the brake pedal fully
pressed when shifting gears. Failure to
follow this instruction could result in
personal injury, death or property
damage.
Note: Read and understand the following
steps and perform them whenever you
prepare to drive the vehicle.
Note: The parking brake does not disengage
unless sufficient system air pressure is
available.
1. Press and hold the service brake pedal
while the engine is running.
2. Select the appropriate drive gear.
3. Push and hold the yellow dash-mounted parking brake knob until
the parking brake light turns off, then
release.
Parking Brake Light Illumination Due
to Low Air Pressure
If the air pressure becomes too low at any
time during vehicle operation, the parking
brake may apply and the parking brake
light turns on.
If the parking brake applies due to low air
pressure, immediate service is required to
the parking brake system.
Releasing Spring Brake with Air
Pressure
The air system in all vehicles with
spring-actuated rear wheel parking brakes
has a valve on the governor for connection
to an outside air supply. The valve lets you
recharge the system with air from an
outside source, releasing the
spring-actuated parking brakes. Your
vehicle is now ready to tow in an
emergency. You can only use an outside air source if
the protected system is in operating
condition. If you cannot restore air pressure
in the protected air system, you must
release the spring-actuated brakes
manually.
Releasing Spring Manually
Do not use impact wrenches as they may
damage the piston and prevent proper
caging of the spring. Do not apply more
than
50 lb.ft (68 Nm) to the release bolt
nut.
1. Remove the stud tool and nut from the
carrying pocket on the brake chamber
assembly. 2. Remove the access plug from the end
of the spring chamber.
3. Insert the release stud through the opening in the chamber and into the
spring pressure plate. 4.
Turn the release stud ¼ turn to engage
the stud tangs with the slot in the
pressure plate. Keep the stud engaged
and install the nut on the release stud.
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5. Tighten the nut until the spring is fully
caged and brakes released. Do not
loosen or remove the release stud and
nut unless you completely assemble
and securely clamp the brake chamber.
6. After restoring the air pressure, unscrew and remove the release stud
and install in the carrying pocket. Install
the access plug.
HILL START ASSIST WARNING: The system does not
replace the parking brake. When you
leave your vehicle, always apply the
parking brake. WARNING:
You must remain in
your vehicle when the system turns on.
At all times, you are responsible for
controlling your vehicle, supervising the
system and intervening, if required.
Failure to take care may result in the loss
of control of your vehicle, serious
personal injury or death. WARNING:
The system will turn
off if a malfunction is apparent or if you
rev the engine excessively. Failure to take
care may result in the loss of control of
your vehicle, serious personal injury or
death.
The system makes it easier to pull away
when your vehicle is on a slope without the
need to use the parking brake.
When the system is active, your vehicle
remains stationary on the slope for two to
three seconds after you release the brake
pedal. This allows time to move your foot
from the brake to the accelerator pedal.
The system releases the brakes
automatically once the engine has developed sufficient torque to prevent your
vehicle from rolling down the slope. This
is an advantage when pulling away on a
slope, for example from a car park ramp,
traffic lights or when reversing uphill into
a parking space.
The system activates on any slope that
causes your vehicle to roll.
Note:
There is no warning light to indicate
the system is either on or off.
Using Hill Start Assist
1. Press the brake pedal to bring your vehicle to a complete standstill. Keep
the brake pedal pressed and shift into
first gear when facing uphill or reverse
(R) when facing downhill.
2. If the sensors detect that your vehicle is on a slope, the system activates
automatically.
3. When you remove your foot from the brake pedal, your vehicle remains on
the slope without rolling away for
about two to three seconds. This hold
time automatically extends if you are
in the process of driving off.
4. Drive off in the normal manner. The system releases the brakes
automatically.
Note: When you remove your foot from the
brake pedal and press the pedal again when
the system is active, you will experience
significantly reduced brake pedal travel. This
is normal.
Switching the System On and Off
Vehicles with Manual Transmission
You can switch this feature on or off in the
information display. The system
remembers the last setting when you start
your vehicle.
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Vehicles with Automatic Transmission
You cannot turn the system on or off.
When you switch the ignition on, the
system automatically turns on.
AIR BRAKES (IF EQUIPPED)
WARNING: Do not drive or continue
to drive if the low air pressure buzzer is
sounding or the brake warning light is lit.
These warnings indicate that air pressure
is not to normal operating level.
Continued use of the vehicle could result
in loss of braking ability. WARNING:
Avoid repeated light
application of the brake pedal. This
depletes air pressure faster and could
result in loss of braking capability. WARNING:
Do not move the
vehicle when the air pressure is
insufficient because the brake system
may be inoperative.
After starting the engine, give the air
compressor time to build up the air
pressure to
60 psi (414 kPa) before moving
your vehicle. Periodically check the air pressure gauge
while driving. Pressure should range
between approximately 100 psi (690 kPa)
to
130 psi (896 kPa). The air compressor
governor cut-in and cutout pressure
settings are set at the factory and are not
adjustable. When air pressure is insufficient
(below
60 psi (414 kPa)), a
warning light illuminates and a
buzzer sounds when the ignition is in the
on position. This may happen because
excessive brake applications are depleting
the system air pressure. If this condition
occurs, stop driving your vehicle until the
compressor has fully recharged the air
system.
Select a gear ratio to help slow your vehicle
before descending grades. Supplementing
with brakes, as required, help to safely slow
the vehicle and avoids overspeeding the
engine.
Air Chamber Stroke Indication
Air chamber push rods have orange stroke
indicator markers that warn when the
braking system requires adjustment or
repair. The painted orange indicator is on
the air chamber push rod at the slack
adjuster stroke dimension that requires
service when visible during brake
application.
A qualified service technician should
perform air brake inspection and
adjustment or repairs keeping to the
instructions in the service manual.
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