
SELECTIVE CATALYTIC REDUCTION (SCR) SYSTEM (DIESEL
ENGINE ONLY)
Your vehicle is equipped with a selective catalytic reduction (SCR)
system to help reduce emission levels of oxides of nitrogen from the
exhaust of the diesel engine. The system automatically injects diesel
exhaust fluid (DEF) into the exhaust system to enable proper SCR
function.
Importance of Maintaining the DEF Level
In order for the SCR system to operate properly, the DEF level must be
maintained. Generally, the DEF tank should be filled before the DEF
gauge in the instrument cluster reaches the first low level warning
(seeWarning messages and vehicle operations).
The engine control unit monitors the amount of fluid available in the
DEF tank. Failure to maintain an adequate amount of DEF in the system
generates warning messages that appear in the information display and,
unless the DEF tank is refilled, leads to a forced reduction of engine
operations.
Warning Messages and Vehicle Operations
The instrument cluster contains a DEF gauge and indicator lights to alert
you to any low DEF level conditions. The indicator lights illuminate if the
DEF gauge level drops below 0.5 gallons (1.9 liters) in the 5 gallon
(19.0 liters) DEF tank or 1 gallon (3.8 liters) in the 9 gallon (34.0 liters)
DEF tank.
Upon filling the DEF tank after a low level warning, normal operation
resumes when the vehicle is restarted.
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If any of these warnings appear, the contaminated DEF must be purged
and replaced with approved DEF. See an authorized dealer or the
Workshop Manual.
Upon filling the DEF tank after a DEF contaminated warning, normal
operation resumes when the vehicle is restarted.
DEF Guidelines and Information
•DEF is non-flammable, non-toxic, colorless and water-soluble.
•Use only DEF that carries the trademark: AMERICAN PETROLEUM
INSTITUTE CERTIFIED DIESEL EXHAUST FLUID.
•An ammonia odor may be smelled when the cap is removed or during
a refill. Refill the DEF tank in a well-ventilated area.
•Prior to filling the tank, make sure the surrounding area is clean of
debris to prevent contamination.
•Do not dilute DEF with water or any other liquid.
•Do not put DEF in the fuel tank or any other tank on the vehicle.
•Do not re-use the nozzle or the DEF container once it is emptied.
•Do not overfill the DEF tank.
•Avoid spilling DEF on painted surfaces, carpeting or plastic
components. Immediately wipe away any DEF that has spilled on
painted surfaces with a damp cloth and water. If it has already
crystallized, use warm water and a sponge.
•DEF freezes below 12°F (-11°C). Your vehicle is equipped with an
automatic pre-heating system which allows the DEF system to
operate below 12°F (-11°C).
•Do not store the DEF bottle in your vehicle. If it leaks, it could cause
damage to interior components or release an ammonia odor inside the
vehicle.
•Store DEF out of direct sunlight and in temperatures between
23°F–68°F (-5°C–20°C).
NOISE EMISSIONS
In order to comply with the federal exterior noise regulations, your
vehicle may be equipped with noise emission items. Depending on the
vehicle configuration, it may have all or some of the following items:
Air Intake System:Inspect the air cleaner. Do not alter its location. Do
not alter inlet and outlet piping.
Body:Inspect wheel well splash shields, cab shields and underhood
insulation for deterioration, dislocation and orientation.
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MANUAL TRANSMISSION OPERATION (IF EQUIPPED)
Manual transmission shift patterns are displayed on either the shift lever
knob or the sun visor. Study this information carefully before you drive
the vehicle even though you may be familiar with similar units. Do not
attempt to drive the vehicle without knowing the exact shift pattern of
the transmission. Consult your authorized dealer if any questions exist as
to the shifting instructions posted in your vehicle.
Driving Hints
WARNING:Do not coast the vehicle with the clutch pedal
pressed or with the transmission in neutral. This practice could
result in loss of vehicle control.
The following driving hints are provided as a brief, general guide in
operating the different manual transmissions used in your vehicle.
•When shifting into first gear or reverse with your vehicle standing
still, quickly release and press the clutch pedal (if necessary to
complete gear engagement).
•Always use the lowest (or most appropriate) gear to start the vehicle.
•Always use a gear ratio low enough to allow the engine to operate
above the minimum engine operation speed range.
•Do not lug the engine.
•Do not slam or jerk the gearshift lever into gear.
•When more power is required, shift to a lower gear and accelerate
the engine near the governed speed.
To go forward, press the clutch pedal in and shift into first gear while
the engine is idling. Engage the clutch while pressing the accelerator to
start forward. Operate the clutch and upshift as required by driving
conditions.
To go backward, put the gearshift lever in reverse and engaging the
clutch while pressing lightly on the accelerator.
Shifting with a Synchronized Transmission
With the clutch pedal pressed in, use the second gear synchronizer to
stop the clutch disc rotation; this allows smooth engagement of first gear
or reverse. To complete the gear engagement, it may be necessary to
apply light pressure to the gearshift lever during initial engagement of
the clutch. It takes a second or two to match gear speeds; steady
pressure on the gearshift lever helps the synchronizer perform its job
more quickly. If the gearshift lever is forced into position, this action
defeats the purpose of the synchronizer by causing gear clash.
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The differential can be locked or unlocked when the vehicle is moving at
a constant speed of under 25 mph (40 km/h) and while the wheels are
not slipping. The differential must not be locked when the vehicle is
traveling down steep grades and 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 the vehicle is restarted or the differential lock switch is turned off
then back on.
Turn the engine off and raise all drive wheels of the locker differential
axle in order to prevent the vehicle from moving when servicing the
wheels, tires or brakes. Axles equipped with a NoSPIN Detroit Locker
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.
Care should be taken to avoid sudden accelerations when both drive
wheels are on a slippery surface.
WARNING:Sudden accelerations 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.
Fluid Temperature
Axle operating temperatures normally do not exceed 100°F (38°C).
If the operating temperature exceeds 230°F (110°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. Extreme Pressure (EP) lubricants should not be run
consistently above 230°F (110°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.
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It is not recommended, or approved, for axle conversions to be
performed. However, it is understood that, on occasion, aftermarket
add-on axles are installed by others on the truck chassis which allow
operator control for weight transfer from other axles (i.e., air lift axles).
TWO-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. These ranges can also
be used to provide additional steps
between transmission shifts when
driving on steep grades or fuel
economy may be factors.
Axle Shifting with a Manual Transmission
To downshift, select the next lower gear, release and press the
accelerator pedal rapidly, or while holding the accelerator pedal down,
release and engage the clutch rapidly.Note:The clutch method is
recommended when driving at slower speeds.
To upshift, keep the accelerator pedal down, select the next higher gear,
release the accelerator and pause until the axle upshifts.Note:
De-clutch for smoother axle upshifts when driving at slower speeds.
Axle Shifting with an Automatic Transmission
Note:You cannot split-shift with an automatic transmission. Also,
downshifting above 40 mph (64 km/h) may result in transmission or axle
damage.
Note:Do not shift the axle to LOW with the vehicle in motion.
Use LOW when you drive a fully-loaded vehicle on a severe grade or in
congested traffic. Press the upper portion of the switch.
Use HIGH for all normal driving conditions with a lightly-loaded or
partially-loaded vehicle. Press the lower portion of the switch.
2SPD
LOW
HIGH
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GENERAL INFORMATION
All standard equipment brakes are designed to be self-adjusting.
Automatic adjustment, when required, occurs whenever the brakes are
applied and released during forward or reverse operation.
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 and should be inspected by an authorized dealer. If the vehicle
has continuous vibration or shudder in the steering wheel while braking,
the vehicle should be inspected by an authorized dealer.
Know the required stopping distances for all driving conditions that may
be encountered. For longer brake lining life, take full advantage of engine
braking power when coming to a stop.
WARNING:Do not drive with your foot resting on the brake
pedal. This results in abnormally high brake temperatures,
excessive lining wear and increased stopping distances.
Before descending a long or steep hill, shift to a lower gear and avoid
continuous application of the brakes. Normally, choose the same gear to
descend the hill that you use to ascend the hill.
WARNING:Continuous application of the brakes causes the
brakes to overheat, resulting in a temporary loss of braking.
See theInstrument Clusterchapter for information on the
brake system warning light.
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 Brakes Do Not Grip Well
•If you have been driving through deep water, gently apply the brakes
several times while the vehicle is moving slowly.
•Let the brakes cool if you have been using them excessively, as in
mountain driving or after several fast, high-speed stops.
•Check brake adjustment.
•Check brake linings for excessive wear.
•Check system air pressure on vehicles equipped with air brakes.
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Anti-lock Brake System (ABS)
This system helps you maintain steering control during emergency stops
by keeping the brakes from locking.
The ABS lamp momentarily illuminates when the ignition is
turned on. If the light does not illuminate during start-up,
remains on or flashes, the ABS may be disabled and may need
to be serviced.
If the ABS is disabled, normal braking is still effective. If the
brake warning lamp illuminates, have your brake system
serviced immediately.
If a PLC trailer is connected when the ignition is switched on,
the trailer ABS light also illuminates. If the light fails to
illuminate, remains on after the vehicle is started or continues
to flash, have the system serviced immediately.
FULL POWER BRAKE SYSTEM
WARNING:If the red BRAKE warning lamp in the instrument
cluster remains illuminated after engine start up, this indicates a
system failure in the Full Power Brake System. Stop the vehicle safely
as soon as possible and seek service immediately.
This system incorporates standard braking, an anti-lock braking system
(ABS) and optional Power Park Brake into one fully-integrated hydraulic
brake system. With the Full Power Brake System, braking energy is
stored, similar to an air brake system, resulting in faster response times
and shorter stopping distances. This is accomplished using motor and
pump assemblies that pressurize the system by pumping brake fluid into
accumulators. This is similar to the air compressor of an air brake system
pressurizing the air tanks. The system includes a master cylinder that
provides the normal pedal feel and transfers the pedal force, via brake
fluid, to the main components of the system.
Note:The motor and pumps run momentarily with the ignition switch in
the on or run position, or in the off position with the brake pedal
pressed.
Note:During normal driving, the pump and motors may be heard
replenishing the accumulators. This is a normal function of the system.
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AIR BRAKES
After starting the engine, give the air compressor time to build up the air
pressure to 60 psi (414 kPa) before moving the vehicle.
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.
Periodically check the air pressure
gauge while driving. Pressure should
range between approximately
100–125 psi (690–862 kPa). The air
compressor governor cut-in and
cut-out 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 condition may be caused by excessive brake applications depleting
the system air pressure. If this condition occurs, stop driving the vehicle
until the compressor has fully recharged the air system.
WARNING:Do not move the vehicle when the air pressure is
insufficient because the brake system may be inoperative.
Select a gear ratio to help slow your vehicle before descending grades.
Supplement with brakes as required to safely slow the vehicle and avoid
overspeeding the engine.
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