Page 105 of 376
Notice:Over-tightening the park brake lever can
cause damage to the park brake system.
Over-tightening is possible by turning the knob
more than half a turn.
Over-tightening is similar to driving down the road with
your regular brakes applied. If the park brake system
is over-tightened the vehicle may seem sluggish
to accelerate, and/or the park brake hand lever maybe
very hard to pull up and apply the park brake.
If the park brake is over-tightened turn the knob to the
right until it stops and follow the parking brake
adjustment procedure.
Vehicles with a foot-pedal park brake system must be
serviced to make this adjustment. SeeScheduled
Maintenance on page 6-5for more information.Parking Brake (With Air Brakes)
If the vehicle has air
brakes, you will have this
parking brake. It is located
above the audio system in
the instrument panel.
Pulling it out applies the parking brake. The parking
brake light will come on when the air parking brake is
applied.
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Vehicles built for use as tractors or towing vehicles have
two air brake controls. They look like this:
{CAUTION:
When the yellow PARKING BRAKE and the red
TRAILER AIR SUPPLY knobs are both pushed in,
the rig will be free to move. It could strike
someone or something. When both of these knobs
are pushed in, hold the regular brake pedal down
to keep the rig from moving.To charge a trailer’s air brake system do the following:
1. Move the vehicle into the proper position.
2. Apply the parking brake by pulling the yellow
parking brake knob out.
3. Hook up the trailer air system properly.
4. Get into the vehicle.
5. Push and hold down the regular brake pedal.
6. Push in both the yellow parking brake and the red
trailer air supply knobs. This will charge the trailer’s
air system.
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). SeeAir Pressure
Gage on page 3-47for more information.
For driving with a trailer, the yellow and red knobs, if
equipped, must be pushed in. When you are not pulling a
trailer, the red trailer air supply knob must be pulled out.
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{CAUTION:
If you apply any one of the air brake parking
controls while the vehicle is moving, the rig will
stop suddenly. If you are not ready for this, you or
others could be injured. Do not apply any one of
these controls while you are 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 warning light and
buzzer will come on. If the air pressure drops to
35 to 45 psi (241 to 310 kPa), the red trailer air supply
knob will automatically pop out and apply the spring
brakes on the trailer.
If the air pressure drops to 35 to 45 psi (241 to 310 kPa),
the yellow park brake knob will automatically pop out
and apply the spring brakes on the truck or tractor.
If you ever have a complete loss of air so that the air
brakes automatically apply, there is a way that the
tow operator can release the parking brakes to tow the
vehicle. SeeTowing Your Vehicle on page 4-23.
Parking Brake Burnish Procedure
All vehicles which have hydraulic brakes have a parking
brake. It is recommended that the 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:
1. Make sure that there is no other traffic around,
bring the vehicle speed up to 20 mph (32 km/h)
and apply the parking brake. Let the vehicle come
to a complete stop. Apply the base brakes and
disengage the parking brake.
2. Repeat the burnishing procedure in Step 1 a total
of 10 times.
3. Between stops, drive the vehicle about
2.5 miles (4 km).
Notice:Driving with the parking brake on can
damage the transmission and brake system parts.
Verify that the parking brake is fully released and the
brake warning light is off before driving.
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Page 108 of 376

Air Suspension
The vehicle may have the Hendrickson HAS Series
single-axle air suspension which is designed for
a single-axle on-highway use. This feature is available
in 19,000 lb (8 613.3 kg), 21,000 lb (9 525.4 kg)
and 23,000 lb (10 432.6 kg) capacities.
Rear Air Suspension Dump Control
If the vehicle is equipped with the Hendrickson HAS
Series single-axle air suspension, you may have
this control. The air suspension dump control allows the
operator to lower the deck height approximately
4.5 inches (11.5 cm) from the normal frame height.
The switch to deflate and
inflate the air suspension
is located on the
instrument panel.Press the bottom of the switch to deflate the air
suspension and lower the deck height. Press the top of
the switch to return the suspension to normal deck height.
An indicator light will come on and stay on whenever
the switch is in the dump position.
Parking Over Things That Burn
{CAUTION:
Things that can burn could touch hot exhaust
parts under the vehicle and ignite. Do not park
over papers, leaves, dry grass, or other things that
can burn.
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Page 109 of 376

Engine Exhaust
{CAUTION:
Engine exhaust contains Carbon Monoxide (CO)
which cannot be seen or smelled. Exposure to CO
can cause unconsciousness and even death.
Exhaust may enter the vehicle if:
•The vehicle idles in areas with poor ventilation
(parking garages, tunnels, deep snow that
may block underbody airflow or tail pipes).
•The exhaust smells or sounds strange or
different.
•The exhaust system leaks due to corrosion or
damage.
CAUTION: (Continued)
CAUTION: (Continued)
•
The vehicle’s exhaust system has been
modified, damaged or improperly repaired.
•There are holes or openings in the vehicle
body from damage or after-market
modifications that are not completely sealed.
If unusual fumes are detected or if it is suspected
that exhaust is coming into the vehicle:
•Drive it only with the windows
completely down.
•Have the vehicle repaired immediately.
Never park the vehicle with the engine running in
an enclosed area such as a garage or a building
that has no fresh air ventilation.
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Page 110 of 376

Diesel Particulate Filter
The vehicle has a Diesel Particulate Filter (DPF) as part
of the exhaust system to reduce vehicle emissions. The
DPF requires a unique exhaust tailpipe with an exhaust
cooler. The exhaust cooler mixes air with the exhaust to
lower the temperature before it leaves the tailpipe.
The DPF, the tailpipe, or other exhaust system
components must not be altered. Inspect regularly and
clean any mud or dirt from the exhaust cooler,
especially where the exhaust cooler connects to the
tailpipe and the openings where fresh air enters
the cooler. See “Exhaust System Inspection” underAt
Least Twice a Year on page 6-27.
The DPF will clean itself as part of normal operation.
Several factors including fuel consumed, hours of engine
operation and miles driven are monitored by the Engine
Control Module (ECM). The self cleaning occurs
approximately once per tank of fuel.
During self cleaning, the
green DPF indicator light
will come on. See
Diesel Particulate Filter
Warning Light on
page 3-46.To clean the filter, either drive the vehicle above 30 mph
(50 km/h) to activate self cleaning, or stop the vehicle
and perform the manual cleaning procedure. For
self cleaning, drive until the green DPF indicator light
goes off. This will take approximately 20 minutes. Once
self cleaning has started, drive until the green indicator
light goes off to complete the cleaning in a single
operation if possible.
Extended idling can cause exhaust parts and gases to
become very hot. Keep the exhaust area clear of
material that could ignite or burn. SeeParking Over
Things That Burn on page 2-44for more information.
{CAUTION:
During DPF self cleaning or during extended idling
in P (Park), the exhaust system and exhaust
gases are very hot. Things that burn could touch
hot exhaust parts under the vehicle and ignite.
You or others could be burned. Do not park, or
idle for an extended period of time, near or over
papers, leaves, dry grass, or other things that can
burn. Keep the exhaust area clear of material that
could ignite or burn. SeeParking Over Things
That Burn on page 2-44for more information.
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Notice:Extended idle should be avoided because
the DPF system is not capable of self cleaning at
idle. During extended idle operation, monitor the
instrument panel telltale lights and Driver Information
Center for messages and take appropriate indicated
action. Continued idling with the warning light/
message on could cause irreversible damage to the
DPF requiring repair and possible replacement that
might not be covered by the vehicle warranty.
When the yellow DPF indicator comes on, the filter is
dirty and needs cleaning. You will also notice a change
in the exhaust sound and engine idle speed. This is
normal. If you continue to drive and the exhaust filter is
not cleaned as required, the DPF indicator will change
from yellow to red. Continuing to drive the vehicle
with the red indicator can cause filter damage.
Vehicles with DPF have specific fuel and engine oil
requirements. SeeWhat Fuel to Use on page 5-8and
Engine Oil (DURAMAX Diesel Engine) on page 5-24
orEngine Oil (Caterpillar Diesel Engine) on page 5-27or
Engine Oil (Isuzu Diesel Engine) on page 5-28or
Engine Oil (Gasoline Engine) on page 5-32for more
information on those requirements.Notice:Permanent damage can occur to the DPF
or related components if the required Ultra Low
Sulfur Diesel (15 ppm sulfur maximum) or low ash
CJ-4 engine oil is not used. This damage would
not be covered by the vehicle warranty.
For vehicles with Power Take-Off (PTO), monitor the
instrument panel cluster for lights related to the DPF.
All engines consume some amount of engine oil. Ash
is the by-product of engine oil consumption. The ash will
become trapped in the DPF over the life of the vehicle.
Eventually, the buildup of ash will restrict the exhaust
gases and the DPF will need to be cleaned or replaced.
SeeAccessories and Modifications on page 5-3for
important information if you are considering adding
accessories or modifying the vehicle.
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Manual Cleaning Procedure
{CAUTION:
During DPF self cleaning, the exhaust system and
exhaust gases are very hot. Stay clear of the
tailpipe area and do not park over things that burn.
You or others could be burned or the vehicle could
catch fire. SeeParking Over Things That Burn on
page 2-44.
If the yellow or red DPF indicator is on, you can clean
the DPF by performing a manual cleaning.When it is safe to do so, stop the vehicle. Perform DPF
manual cleaning in a well ventilated area. DPF Manual
cleaning must be performed outdoors, as follows. Once
manual cleaning is started, complete the manual cleaning
in a single operation if possible. If manual cleaning is not
completed, as indicated by the green DPF indicator going
off, and the yellow or red indicator light remains on, self
cleaning might not be allowed until the vehicle is stopped
and manual cleaning is performed until completed.
1. Check engine oil and engine coolant levels to be
sure they are at proper operating levels.
2. To prevent running out of fuel during manual
cleaning, make sure there is at least a quarter of a
tank of fuel.
3. Check to make sure the area near the exhaust
tailpipe and under the exhaust system are clear
of any materials that could catch fire. Keep people
away from the area of the exhaust system and
exhaust gases.
2-48