Paccar TX-8 User manual

Operator’s Manual
Operator’s Manual
8 Speed
Transmission
8 Speed
Transmission
TX-8

Safety..................................... 1
Features..................................... 2
Indications and Controls..................................... 3
Operation..................................... 4
Maintenance..................................... 5
Information..................................... 6
Contents

© 2021 PACCAR Inc. - All Rights Reserved
This manual illustrates and describes the operation of features or equipment which may be either
standard or optional on this vehicle. This manual may also include a description of features and
equipment which are no longer available or were not ordered on this vehicle. Please disregard any
illustrations or descriptions relating to features or equipment which are not on this vehicle. PACCAR
reserves the right to discontinue, change specifications, or change the design of its vehicles at any
time without notice and without incurring any obligation. The information contained in this manual is
proprietary to PACCAR. Reproduction, in whole or in part, by any means is strictly prohibited without
prior written authorization from PACCAR Inc.
Contents

Chapter 1 | SAFETY
Using this Manual..................................................................................................................................5
Safety Alerts..........................................................................................................................................5
Illustrations............................................................................................................................................6
General Safety Instructions...................................................................................................................6
Repairs..................................................................................................................................................9
SAFETY -
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1

Using this Manual
Please take the time to get acquainted with
your vehicle by reading this Operator’s
Manual. We recommend that you read and
understand this manual from beginning to
end before you operate this equipment.
This manual contains useful information for
the safe and efficient operation of this
equipment. It also provides service
information, with an outline for performing
safety checks and basic preventive
maintenance inspections. We have tried to
present the information needed to learn
about functions, controls, and operation—
and to present it as clearly as possible.
Occasionally, you may need to reference
this manual, and we hope you find is easy
to use.
NOTE
After you've read this manual, it should
be stored in the cab for convenient ref-
erence and remain with this truck
when sold.
Your vehicle may not have all the features
or options mentioned in this manual.
Therefore, you should pay careful attention
to the instructions that pertain to just your
vehicle. In addition, if your vehicle is
equipped with special equipment or options
not discussed in this manual, consult your
dealer or the manufacturer of the
equipment.
There are several tools built into this
manual to help you find what you need
quickly and easily; first is the Table of
Contents. Located at the front of the
manual, this table arranges the subject
matter into chapters, which can be quickly
referenced using the numbers shown in the
outer margin. The first page of each
chapter presents a list of the major
subjects contained in that chapter. Cross-
referenced citations can also help you find
information. If more information on the
current subject is located elsewhere in the
manual, a cross-reference may be
provided, such as "see Safety Alerts on
page 5."
Finally, you’ll find a helpful index at the
back of the manual, which lists the subjects
covered, alphabetically.
All information contained in this manual is
based on the latest production information
available at the time of publication.
Kenworth Truck Company reserves the
right to make changes at any time without
notice.
Safety Alerts
Read and follow all of the safety alerts
contained in this manual. They are there
for your protection and information. These
alerts can help you avoid injury to yourself,
your passengers, and help prevent costly
damage to the vehicle. Safety alerts are
highlighted by safety alert symbols and
signal words such as WARNING,
CAUTION, or NOTE. Do not ignore any of
these alerts.
Warnings
The safety message following this symbol
and signal word provides a warning against
operating procedures that could cause
death or injury. They could also cause
equipment or property damage. The alert
will identify the hazard, how to avoid it, and
the probable consequence of not avoiding
the hazard.
Example:
SAFETY - Using this Manual
Y53-1331 (6/21) 5
1

WARNING
Hot engine oil can be dangerous. You
could be burned. Let the engine oil
cool down before changing it. Failure
to comply may result in death, person-
al injury, equipment or property dam-
age.
Cautions
The safety message following this symbol
and signal word provides a caution against
operating procedures that could cause
equipment or property damage. The alert
will identify the hazard, how to avoid it, and
the probable consequence of not avoiding
the hazard.
Example:
CAUTION
Continuing to operate your vehicle with
insufficient oil pressure will cause seri-
ous engine damage. Failure to comply
may result in equipment or property
damage.
Notes
The message following this symbol and
signal word provides important information
that is not safety related but should be
followed. The alert will highlight things that
may not be obvious and is useful to your
efficient operation of the vehicle.
Example:
NOTE
Pumping the accelerator will not assist
in starting the engine.
Illustrations
Some of the illustrations found in this
manual are generic, and may not look
exactly like the parts or assemblies you
find installed on your vehicle.
When an illustration differs from what you
see physically present on your vehicle, the
language describing the procedure will still
be correct for your application.
General Safety
Instructions
WARNING
Improper practices, carelessness, or
ignoring any warnings may cause
property damage, personal injury, or
death.
WARNING
Manually rotating the crankshaft re-
quires a trained technician and specialty
tools. DO NOT pull or pry on the fan in
an attempt to rotate the crankshaft. Ap-
plying force to the fan can damage the
fan blades or cause premature fan fail-
ure. Failure to comply with the approved
procedure may result in property dam-
age, personal injury, or death.
SAFETY - Illustrations
6 Y53-1331 (6/21)
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Before performing any repair, read and
understand all of the safety precautions
and warnings. The following is a list of
general safety precautions that must be
followed to provide personal safety. Failure
to follow these instructions may cause
death or injury. Special safety precautions
are included in the procedures when they
apply.
Keep in mind that even a well maintained
vehicle must be operated within the range
of its mechanical capabilities and the limits
of its load ratings. See the Weight Ratings
label on the driver's door edge.
Every new vehicle is designed to conform
to all Federal Motor Vehicle Safety
Standards applicable at the time of
manufacture. Even with these safety
features, continued safe and reliable
operation depends greatly upon regular
vehicle maintenance. Follow the
maintenance recommendations found in
the Preventive Maintenance section. This
will help preserve your investment.
Make sure your vehicle is in top working
condition before heading out on the road, it
is the responsible driver's duty to do so.
Inspect the vehicle according to the
Driver's Check List.
• Work areas should be dry, well lit,
well ventilated, free from clutter,
loose tools, parts, ignition sources
and hazardous substances.
• Wear protective glasses and
protective shoes when working.
• Wear protective gloves when
working with hot liquids or
surfaces.
• DO NOT wear loose-fitting or torn
clothing. Tie back and/or tuck in
long hair. Remove all jewelry when
working.
• Before beginning any repair,
disconnect the battery (negative [-]
cable) and discharge any
capacitors.
• Put a “DO NOT OPERATE” tag in
the operator's compartment or on
the controls.
• Allow the engine to cool before
slowly loosening the coolant fill cap
to relieve the pressure from the
cooling system.
WARNING
Removing the fill cap on a hot engine
can cause scalding coolant to spray
out and burn you badly. If the engine
has been in operation within the previ-
ous 30 minutes, be very careful in re-
moving the fill cap. Protect face,
hands, and arms against escaping flu-
id and steam by covering the cap with
a large, thick rag. DO NOT try to re-
move it until the surge tank cools down
or if you see any steam or coolant es-
caping. Always remove the cap very
slowly and carefully. Be ready to back
off if any steam or coolant begins to
escape. Failure to comply may result
in death, personal injury, equipment or
property damage.
• Always use wheel chocks or proper
jack stands to support the vehicle
or vehicle components before
performing any service work. DO
NOT work on anything that is
supported only by lifting jacks or a
hoist. Before resting a vehicle on
jack stands, be sure the stands are
rated for the load you will be
placing on them.
• Before removing or disconnecting
any lines, fittings, or related items,
relieve all pressure in the air, oil,
fuel, and cooling systems. Remain
alert for possible pressure when
disconnecting any device from a
SAFETY - General Safety Instructions
Y53-1331 (6/21) 7
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system that contains pressure.
High pressure oil or fuel can cause
death or personal injury.
• Always wear protective clothing
when working on any refrigerant
lines and make sure that the
workplace is well ventilated.
Inhalation of fumes can cause
death or personal injury. To protect
the environment, liquid refrigerant
systems must be properly emptied
and filled using equipment that
prevents the release of refrigerant
gas. Federal law requires capturing
and recycling refrigerant.
• When moving or lifting any heavy
equipment or parts, make sure to
use proper techniques and
assistance. Ensure all lifting
devices such as chains, hooks, or
slings are in good condition and
are of the correct load capacity.
Make sure all lifting devices are
positioned correctly.
• Corrosion inhibitors and lubricating
oils may contain alkali. DO NOT
get the substance in eyes and
avoid prolonged or repeated
contact with skin. DO NOT
swallow. If ingested, seek
immediate medical attention. DO
NOT induce vomiting. In case of
contact, immediately wash skin
with soap and water. In case of
harmful contact, immediately
contact a physician. Always keep
any chemicals OUT OF REACH
OF CHILDREN.
• Naphtha and Methyl Ethyl Ketone
(MEK) are flammable materials and
must be used with caution. Follow
the manufacturer's instructions to
ensure safety when using these
materials. Always keep any
chemicals OUT OF REACH OF
CHILDREN.
• When working on the vehicle, be
alert for hot parts on systems that
have just been turned off, exhaust
gas flow, and hot fluids in lines,
tubes, and compartments. Contact
with any hot surface may cause
burns.
• Always use tools that are in good
condition. Make sure you have the
proper understanding of how to use
the tools before performing any
service work. Use only genuine
replacement parts from PACCAR.
• Always use the same fastener part
number (or equivalent) when
replacing items. DO NOT use a
fastener of lesser quality if
replacements are necessary. (e.g.,
DO NOT replace a SAE 10.9 grade
with 8.8 grade fastener.)
• Always torque fasteners and fuel
connections to the required
specifications. Overtightening or
under-tightening can allow leakage.
• Close the manual fuel valves prior
to performing maintenance and
repairs, and when storing the
vehicle inside.
• DO NOT perform any repair when
impaired, tired, fatigued, or after
consuming alcohol or drugs that
can impair your functioning.
• Some state and federal agencies in
the United States of America have
determined that used engine oil
can be carcinogenic and can cause
reproductive toxicity. Avoid
inhalation of vapors, ingestion, and
prolonged contact with used engine
oil.
• DO NOT connect the jump starting
or battery charging cables to any
ignition or governor control wiring.
This can cause electrical damage
to the ignition or governor.
SAFETY - General Safety Instructions
8 Y53-1331 (6/21)
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• Coolant is toxic. If not reused,
dispose of coolant in accordance
with local environmental
regulations.
CAUTION
Corrosive chemicals can damage the
engine. DO NOT use corrosive chemi-
cals on the engine. Failure to comply
may result in equipment or property
damage.
California Proposition 65 Warning
• Diesel engine exhaust and some of
its constituents are known to the
State of California to cause cancer,
birth defects, and other
reproductive harm.
• The catalyst substrate located in
the Diesel Particulate Filter (DPF)
contains vanadium pentoxide,
which has been determined by the
State of California to cause cancer.
Always wear protective clothing
and eye protection when handling
the catalyst assembly. Dispose of
the catalyst in accordance with
local regulations. If catalyst
material gets into the eyes,
immediately flood eyes with water
for a minimum of 15 minutes. Avoid
prolonged contact with skin. In
case of contact, immediately wash
skin with soap and water. In case
of harmful contact, immediately
contact a physician.
• Other chemicals in this vehicle are
also known to the State of
California to cause cancer, birth
defects or other reproductive harm.
• Battery posts, terminals, and
related accessories contain lead
and lead compounds, chemicals
known to the State of California to
cause cancer and reproductive
harm. Wash hands after handling.
Repairs
WARNING
DO NOT attempt repair work without
sufficient training, service manuals,
and the proper tools. You could be kil-
led or injured, or you could make your
vehicle unsafe. Perform only those
tasks you are fully qualified to do.
WARNING
Modifying your vehicle can make it un-
safe. Some modifications can affect
your vehicle's electrical system, stabili-
ty, or other important functions. Before
modifying your vehicle, check with
your dealer to make sure it can be
done safely. Improper modifications
can cause death or personal injury.
CAUTION
The installation of electronic devices to
the On Board Diagnostics (OBD) con-
nector, the vehicle Controller Area Net-
work (CAN), or their associated wiring
is not permitted. Doing so can ad-
versely affect vehicle performance
and/or cause fault codes to be record-
ed. The OBD connector is provided for
temporary connection of service tools
and for diagnostic purposes only.
SAFETY - Repairs
Y53-1331 (6/21) 9
1

Your dealer’s service center is the best
place to have your vehicle repaired. You
can find dealers all over the country with
the equipment and trained personnel to get
you back on the road quickly—and keep
you there.
Your vehicle is a complex machine.
Anyone attempting repairs on it needs
good mechanical training and the proper
tools. However, all warranty repairs must
be performed by a PACCAR Powertrain
distributor. If you aren’t an experienced
mechanic, or don’t have the right
equipment, please leave all repairs to a
PACCAR Powertrain distributor. They are
the ones best equipped to do the job safely
and correctly.
Maintenance Manuals
If you do decide to do any complex repair
work, you’ll need the maintenance
manuals. Order them from your PACCAR
Powertrain distributor. Please provide your
Chassis Serial Number when you order, to
be sure you get the correct manuals for
your vehicle. Allow about four weeks for
delivery. There will be a charge for these
manuals.
Final Chassis Bill of Material
A complete, non-illustrated computer
printout listing of the parts used to custom-
build your vehicle is available through the
dealer from whom you purchased your
vehicle.
SAFETY - Repairs
10 Y53-1331 (6/21)
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SAFETY - Repairs
Y53-1331 (6/21) 11
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Chapter 2 | FEATURES
Auto-neutral.........................................................................................................................................13
Adaptive Driving Mode........................................................................................................................13
Adaptive Starting Gear........................................................................................................................13
Auto-park (option)............................................................................................................................... 13
Engine Overspeed and Underspeed Protection..................................................................................14
Hill Start Aid (option)........................................................................................................................... 14
LOW Mode..........................................................................................................................................14
Neutral Idle Control Plus (NIC+)......................................................................................................... 15
Parking Pawl (option)..........................................................................................................................15
FEATURES -
12 Y53-1331 (6/21)
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Auto-neutral
The Auto-neutral feature will automatically
shift the transmission into Neutral if it is left
in a forward or reverse mode (such as
LOW, Drive, or Reverse) and the parking
brake is set.
NOTE
If Auto-neutral has been activated, the
transmission will not shift into Drive (D)
or Reverse (R) until the shifter is first
moved to Neutral (N) before selecting
another transmission mode.
Adaptive Driving Mode
Adaptive Driving will adjust the
transmission shift schedule based on
driving conditions, improving fuel economy
and performance. This feature incorporates
feedback such as road slope, vehicle
weight, and speed to determine when to
smoothly and efficiently shift between
gears. Adaptive Driving Mode then
remembers these determinations for future
shifting decisions.
The feedback used to determine an ideal
shift schedule also helps protect the
transmission from shift selections falling
outside the acceptable range for the
intended gear. If road slope and vehicle
weight (when compared to the drivetrain
ratio and engine torque) would invalidate
the intended gear, the shift will be denied.
Adaptive Driving Mode is always on.
Adaptive Starting Gear
The Adaptive Starting Gear feature
automatically selects a start gear based on
vehicle weight and road grade. This gear
can be changed, however, using the up/
downshift request procedure as long as the
selection still falls into a gear that allows
the vehicle to launch without causing
damage to the transmission.
NOTE
If the driver attempts to select a non-
neutral mode without applying the
service brake, the transmission will not
shift into gear. If this is attempted, the
driver will need to re-select Neutral (N)
and then press the service brake be-
fore a new mode can be selected.
NOTE
If vehicle weight drops (the operator
removes load), Adaptive Starting Gear
will continue using the same starting
gear employed prior to lightening the
load and will require a 30-second key
cycle (or if equipped with a parking
pawl, remaining in Park for one mi-
nute) to adapt to the new vehicle
weight.
Auto-park (option)
This feature prevents unintentional rolling
should the operator forget to place the
vehicle in Park. If equipped with a parking
pawl, Auto-park will automatically place the
transmission in Park (P) if the operator
moves the ignition switch to OFF while the
vehicle is stationary.
FEATURES - Auto-neutral
Y53-1331 (6/21) 13
2

NOTE
If Auto-park has been activated, the
transmission will not exit Park (P) until
the shifter is first moved to P before
selecting another transmission mode.
Engine Overspeed and
Underspeed Protection
The transmission system will upshift, if
necessary, to prevent damage during an
engine overspeed condition and will also
downshift to prevent engine lug (driving in
a high gear at low rpm) and a potential stall
during an engine underspeed condition.
Engine Overspeed Protection is active in
Drive (D), Manual, and LOW modes;
however, Engine Underspeed Protection is
only active when in Drive (D) mode or
Manual mode.
Hill Start Aid (option)
Hill Start Aid prevents unwanted vehicle
movement on steep grades when
transitioning from the brake to throttle
pedal. Hill Start Aid can be disabled using
the Hill Start Aid Disable switch (see Hill
Start Aid Disable Switch).
Hill Start Aid activates by default on a road
grade of 3% and whenever Neutral Idle
Control Plus (NIC+) is active.
LOW Mode
LOW mode should be used any time you
want to limit upshifting, hold lower gears, or
improve engine braking through lower gear
selection. For example, when driving down
long grades or when coming to a stop.
• Selects lowest available gear for
start gear. The starting gear cannot
be changed in LOW mode.
NOTE
If the driver attempts to select a non-
neutral mode without applying the
service brake, the transmission will not
shift into gear. If this is attempted, the
driver will need to re-select Neutral (N)
and then press the service brake be-
fore a new mode can be selected.
• If LOW is selected while moving,
the transmission will not upshift
(except in conditions requiring
overspeed protection – see Engine
Overspeed and Underspeed
Protection on page 14). The
transmission system will downshift
at the earliest opportunity to enable
higher than normal engine RPM to
provide maximum engine braking.
WARNING
On slippery surfaces minimize engine
braking in LOW mode. Excessive en-
gine braking at higher engine RPM
could cause a loss of traction and vehi-
cle control.
NOTE
This transmission initiates upshifts
from Drive (D), Manual, and LOW
modes for engine overspeed protec-
tion.
FEATURES - Engine Overspeed and Underspeed Protection
14 Y53-1331 (6/21)
2

Neutral Idle Control Plus
(NIC+)
NOTE
NIC+ is only available for vehicles
equipped with air brakes.
This transmission will shift into neutral
when the vehicle is stationary, and the
service or parking brake is applied. NIC+
absolves the engine from providing power
to the drivetrain when the vehicle has
stopped, saving fuel and reducing the
braking effort required by the operator to
keep the vehicle stationary. When the
parking or service brake is released, the
transmission gradually, and automatically,
shifts back into gear, allowing the vehicle to
creep forward normally.
Parking Pawl (option)
This transmission may be equipped with a
park setting that prevents the vehicle from
rolling. The parking pawl is activated using
the gear shift lever and can also be
engaged (by spring force) when the vehicle
is at a standstill and the ignition switch is
turned to OFF. The parking pawl uses the
pawl to lock the transmission output that
engages in the meshing of the output shaft.
This locks the rear wheels by means of the
driveshaft.
Parking Pawl Manual Release
(option)
Transmissions with a Park mode are also
equipped with a way to disengage the
parking pawl directly at the transmission.
Using the manual release places the
transmission in neutral and is useful when
the transmission won't respond to gearing
requests (for example, when the engine
won't start) and the vehicle must be rolled.
See Manually Releasing the Parking Pawl
on page 24.
NOTE
Activating the parking pawl manual re-
lease will allow the vehicle to roll if the
Parking Brake is not set. Make sure
that the vehicle is prepared to be rol-
led, or that the Parking brake is set,
prior to activating the manual release.
FEATURES - Neutral Idle Control Plus (NIC+)
Y53-1331 (6/21) 15
2

Chapter 3 | INDICATIONS AND CONTROLS
Digital Display..................................................................................................................................... 17
Gearshift Lever....................................................................................................................................18
Hill Start Aid Disabled Warning Light (option)..................................................................................... 20
Hill Start Aid Disable Switch (option)...................................................................................................20
Power Take-off (PTO) Switch (option).................................................................................................20
INDICATIONS AND CONTROLS -
16 Y53-1331 (6/21)
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Digital Display
Primary Gauges View
6 D
N
R
The digital display shows the following
indications related to the transmission:
Transmission Gear Display
Transmission Temperature
Transmission Gear Display
The Transmission Gear Display is located
on the Digital Display.
The following indications appear next to D
(Drive), when the feature or condition is
active:
1 – 8Current Gear
AN Auto Neutral
LLOW Mode
MManual Mode
–Shift Position Unknown
The following indications appear next to R
(Reverse), when the feature or condition is
active:
1Multi-reverse Gear
–Shift Position Unknown
The following indications appear generally
in the Gear Display when the feature or
condition is active:
! ≡ Critical Error
Transmission Oil Temperature
Gauge
The Transmission Temperature Gauge
indicates the temperature of the oil in the
INDICATIONS AND CONTROLS - Digital Display
Y53-1331 (6/21) 17
3

transmission. Watch this gauge to know
when the transmission is overheating and if
so, have it checked by an authorized
service representative.
Gearshift Lever
The gearshift is located on the right-hand
side of the steering column and can
perform the following transmission
functions:
• Switch transmission modes
• Upshift and Downshift
• Activate Manual mode
Transmission Modes
Select the transmission mode by rotating
the lever outer knob. There is a position for
Drive (D), Neutral (N), and Reverse (R)
and for some vehicles Park (P).
Rotating the knob to the Park (P) or
Reverse (R) position while the vehicle is
moving forward, or to the Park (P) or Drive
(D) position while the vehicle is moving
backward, will not change the transmission
mode to those selections.
The Digital Display will indicate the
corresponding mode.
NOTE
Vehicles without a Park (P) mode must
be in Neutral (N) to start the engine.
Upshifting and Downshifting
The transmission gear can be selected
manually to accommodate the driving
needs of the operator. The Transmission
Mode must be in Drive (D) to manually
select the gear.
When in Automatic mode
INDICATIONS AND CONTROLS - Gearshift Lever
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