2021 RAM CHASSIS CAB engine

162STARTING AND OPERATING
NOTE:
Pausing in transfer case N (Neutral) in vehi -
cles equipped with an automatic transmis -
sion may require shutting the engine OFF to
avoid gear clash while completing the shift. If
difficulty occurs, shift the transmission into
Neutral, hold your foot on the brake, and turn
the engine OFF. Complete the range shift to
the desired mode.

Shifting into or out of 4L is possible with the
vehicle completely stopped, however difficulty
may occur due to the mating clutch teeth not
being properly aligned. Several attempts may
be required for clutch teeth alignment and
shift completion to occur. The preferred
method is with the vehicle rolling 2 to 3 mph
(3 to 5 km/h). Avoid attempting to engage or
disengage 4L with the vehicle moving faster
than 2 to 3 mph (3 to 5 km/h).

Do not attempt to shift into or out of 4L while
the transmission is in gear.
Transfer Case Position Indicator Light
The “Transfer Case Position Indicator Light” in
the instrument cluster is used to alert the driver
that the front axle is fully engaged and all four
wheels are driving.
LIMITED-SLIP DIFFERENTIAL
The limited-slip differential provides additional
traction on snow, ice, mud, sand and gravel,
particularly when there is a difference between
the traction characteristics of the surface under
the right and left rear wheels. During normal
driving and cornering, the limited-slip unit
performs similarly to a conventional differential.
On slippery surfaces, however, the differential
delivers more of the driving effort to the rear
wheel having the better traction.

The limited-slip differential is especially helpful
during slippery driving conditions. With both rear
wheels on a slippery surface, a slight application
of the accelerator will supply maximum traction.
When starting with only one rear wheel on an
excessively slippery surface, slight momentary
application of the parking brake may be
necessary to gain maximum traction.
Care should be taken to avoid sudden
accelerations when both rear wheels are on a
slippery surface. This could cause both rear
wheels to spin, and allow the vehicle to slide
sideways on the crowned surface of a road or in
a turn.
WARNING!
On vehicles equipped with a limited-slip
differential never run the engine with one rear
wheel off the ground since the vehicle may
drive through the rear wheel remaining on the
ground. You could lose control of the vehicle.

21_DPF_OM_EN_USC_t.book Page 162

STARTING AND OPERATING163
POWER TAKE OFF (PTO) OPERATION — IF
EQUIPPED

This vehicle when equipped with PTO Prep and
the AS66RC/AS69RC automatic six-speed, will
allow for an aftermarket upfit with a transmission
driven PTO (power take off). The customer will
have the ability to operate the PTO in either
a “stationary”, “mobile” or “remote” mode.
The vehicles will be factory set to the “stationary”
mode. To select a different mode, or to change
any other PTO setting, you will need to enter the
commercial vehicle menu on the instrument
cluster screen. Details of the PTO selection
modes and further PTO information is available
at the Ram Truck Bodybuilders web site:
https://
www.ramtrucks.com/ram-commercial/
body-builders-guide.html
POWER STEERING
HYDRAULIC POWER STEERING
The standard power steering system will give
you good vehicle response and increased ease
of maneuverability in tight spaces. The system
will provide mechanical steering capability if
power assist is lost.

If for some reason the power assist is interrupted,
it will still be possible to steer your vehicle. Under
these conditions, you will observe a substantial
increase in steering effort, especially at very low
vehicle speeds and during parking maneuvers.

NOTE:
Increased noise levels at the end of the
steering wheel travel are considered normal
and do not indicate that there is a problem
with the power steering system.
Upon initial start-up in cold weather, the
power steering pump may make noise for a
short amount of time. This is due to the cold,
thick fluid in the steering system. This noise
should be considered normal, and it does not
in any way damage the steering system.
Power Steering Fluid Check
Checking the power steering fluid level at a
defined service interval is not required. The fluid
should only be checked if a leak is suspected,
abnormal noises are apparent, and/or the
system is not functioning as anticipated. Check
fluid level when the engine is cold and off.
Coordinate inspection efforts through an
authorized dealer.
CAUTION!
Prolonged operation of the steering system
at the end of the steering wheel travel will
increase the steering fluid temperature and it
should be avoided when possible. Damage to
the power steering pump may occur.
WARNING!
Fluid level should be checked on a level
surface and with the engine off to prevent
injury from moving parts and to ensure
accurate fluid level reading. Do not overfill.
Use only manufacturer's recommended
power steering fluid.
4

21_DPF_OM_EN_USC_t.book Page 163

166STARTING AND OPERATING
(Continued)
The following conditions will also deactivate the
Cruise Control without erasing the set speed
from memory:
Vehicle parking brake is applied
Stability event occurs
Gear selector is moved out of DRIVE
Engine overspeed occurs
Pushing the on/off button, or placing the
ignition in the OFF position, erases the set
speed from memory.
ADAPTIVE CRUISE CONTROL (ACC) — IF
E
QUIPPED

Adaptive Cruise Control (ACC) increases the
driving convenience provided by Cruise Control
while traveling on highways and major roadways.
However, it is not a safety system and not
designed to prevent collisions. The Cruise Control
function performs differently if your vehicle is not
equipped with ACC
Ú
page 164.
ACC will allow you to keep Cruise Control
engaged in light to moderate traffic conditions
without the constant need to reset your speed.
ACC utilizes a radar sensor and a forward facing
camera designed to detect a vehicle directly
ahead of you to maintain a set speed.
NOTE:
If the ACC sensor detects a vehicle ahead,
ACC will apply limited braking or acceleration
(not to exceed the original set speed) auto
-
matically to maintain a preset following
distance, while matching the speed of the
vehicle ahead.
Any chassis/suspension or tire size modifica -
tions to the vehicle will affect the perfor -
mance of the Adaptive Cruise Control and
Forward Collision Warning system.
Fixed Speed Cruise Control alone (an ACC
distance not set) will not detect vehicles
directly ahead of you. Always be aware of the
mode selected.
WARNING!

Adaptive Cruise Control (ACC) is a conve -
nience system. It is not a substitute for active
driver involvement. It is always the driver’s
responsibility to be attentive of road, traffic,
and weather conditions, vehicle speed,
distance to the vehicle ahead; and, most
importantly, brake operation to ensure safe
operation of the vehicle under all road condi -
tions. Your complete attention is always
required while driving to maintain safe
control of your vehicle. Failure to follow these
warnings can result in a collision and death
or serious personal injury.

The ACC system:
Does not react to pedestrians,
oncoming vehicles, and stationary
objects (e.g., a stopped vehicle in a
traffic jam or a disabled vehicle).
Cannot take street, traffic, and weather
conditions into account, and may be
limited upon adverse sight distance
conditions.

21_DPF_OM_EN_USC_t.book Page 166

STARTING AND OPERATING171
To Vary The Speed Setting
To Increase Or Decrease The Set Speed
After setting a speed, you can increase the
set speed by pushing the RES (+) button, or
decrease speed by pushing the SET (-) button.
U.S. Speed (mph)
Pushing the RES (+) button, or SET (-) button
once will result in a 1 mph speed adjustment.
Each subsequent tap of the button results in
an adjustment of 1 mph.
If the button is continually pushed, the set
speed will continue to adjust in 5 mph incre -
ments until the button is released. The new
set speed is reflected in the instrument
cluster display.
Metric Speed (km/h)
Pushing the RES (+) button, or SET (-) button
once will result in a 1 km/h speed adjust -
ment. Each subsequent tap of the button
results in an adjustment of 1 km/h.
If the button is continually pushed, the set
speed will continue to adjust in 10 km/h
increments until the button is released.
The new set speed is reflected in the instru -
ment cluster display. When An ACC Distance Is Also Set: 
When you use the SET (-) button to decel -
erate, if the engine’s braking power does not
slow the vehicle sufficiently to reach the set
speed, the brake system will automatically
slow the vehicle.
 The ACC system applies the brake down to a
full stop when following the vehicle in front.
If your vehicle follows the vehicle in front to
a standstill, your vehicle will release the
brakes two seconds after coming to a
complete stop.
 The ACC system maintains set speed when
driving uphill and downhill. However, a slight
speed change on moderate hills is normal.
In addition, downshifting may occur while
climbing uphill or descending downhill. This
is normal operation and necessary to main-
tain set speed. When driving uphill and
down -hill, the ACC system will cancel if the
braking temperature exceeds normal range
(over -heated).
Setting The Following Distance In ACC

The specified following distance for Adaptive
Cruise Control (ACC) can be set by varying the
distance setting between four bars (longest),
three bars (long), two bars (medium) and one
bar (short). Using this distance setting and the
vehicle speed, ACC calculates and sets the
distance to the vehicle ahead. This distance
setting displays in the instrument cluster display.
Distance Settings

1 — Longest Distance Setting (Four Bars)
2 — Long Distance Setting (Three Bars)
3 — Medium Distance Setting (Two Bars)
4 — Short Distance Setting (One Bar)
4

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STARTING AND OPERATING195
ENGINE RUNAWAY
Diesel engine runaway is a rare condition
affecting diesel engines, where the engine
consumes its own lubrication oil and runs at
higher and higher RPM until it overspeeds to
a point where it destroys itself due to either
mechanical failure or engine seizure through
lack of lubrication.
REFUELING THE VEHICLE — GASOLINE
ENGINE
NOTE:
When the fuel nozzle “clicks” or shuts off the
fuel tank is full. NOTE:
Tighten the gas cap a quarter turn until you hear
one click. This is an indication that the cap is
properly tightened.
If the gas cap is not tightened properly, the
Malfunction Indicator Light will come on.
Be sure the gas cap is tightened every time the
vehicle is refueled.
WARNING!
In case of engine runaway due to flammable
fumes from fuel spills or turbocharger oil
leaks being sucked into the engine, do the
following to help avoid personal injury and/or
vehicle damage:
Turn the ignition switch to the OFF position.

Using a CO2 or dry chemical type fire extin
-
guisher, direct the spray from the fire extin -
guisher into the grille on the passenger side so
that the spray enters the engine air intake.

The inlet for the engine air intake is located
behind the passenger side headlamp and
receives air through the grille.
CAUTION!
Damage to the fuel system or emissions
control system could result from using an
improper fuel tank filler tube cap (fuel filler
cap). A poorly fitting cap could let impurities
into the fuel system. Also, a poorly-fitted
aftermarket cap can cause the MIL
(Malfunction Indicator Light) to illuminate
due to fuel vapors escaping from the
system.
A poorly fitting fuel filler cap may cause the
MIL to turn on.
To avoid fuel spillage and overfilling, do not
“top off” the fuel tank after filling.
WARNING!
Never have any smoking materials lit in
or near the vehicle when the gas cap is
removed or the tank is being filled.
Never add fuel to the vehicle when the
engine is running. This is in violation of
most state and federal fire regulations and
may cause the MIL to turn on.
WARNING!
A fire may result if gasoline is pumped into a
portable container that is inside of a vehicle.
You could be burned. Always place gas
containers on the ground while filling.
4

21_DPF_OM_EN_USC_t.book Page 195

196STARTING AND OPERATING
LOOSE FUEL FILLER CAP MESSAGE
If the vehicle diagnostic system
determines that the fuel filler cap
is loose, improperly installed, or
damaged, a loose gASCAP indicator
will display in the instrument cluster telltale
display area Ú page 90. Tighten the fuel filler
cap properly and push the RIGHT button to turn
off the message. If the problem continues, the
message will appear the next time the vehicle is
started.
REFUELING THE VEHICLE — DIESEL ENGINE
NOTE:
When the fuel nozzle “clicks” or shuts off, the
fuel tank is full.
Tighten the fuel filler cap until you hear a
“clicking” sound. This is an indication that the
fuel filler cap is properly tightened.
Make sure that the fuel filler cap is tightened
each time the vehicle is refueled.
DIESEL EXHAUST FLUID
Your vehicle is equipped with a Selective
Catalytic Reduction (SCR) system to meet the
very stringent diesel emissions standards
required by the Environmental Protection
Agency.

The purpose of the SCR system is to reduce levels
of NOx (oxides of nitrogen emitted from engines)
that are harmful to our health and the
environment to a near-zero level. A small quantity
of Diesel Exhaust Fluid (DEF) is injected into the
exhaust upstream of a catalyst where, when
vaporized, it converts smog-forming nitrogen
oxides (NOx) into harmless nitrogen (N2) and
water vapor (H2O), two natural components of
the air we breathe. You can operate with the
comfort that your vehicle is contributing to a
cleaner, healthier world environment for this and
generations to come.

System Overview
This vehicle is equipped with a Diesel Exhaust
Fluid (DEF) injection system and a Selective
Catalytic Reduction (SCR) catalyst to meet the
emission requirements.
The DEF injection system consists of the
following components:
DEF tank
DEF pump
DEF injector
Electronically-heated DEF lines
DEF control module
NOx sensors
Temperature sensors
SCR catalyst
UQS Sensor
For system messages and warnings Úpage 90.
CAUTION!
To avoid fuel spillage and overfilling, do not
“top off” the fuel tank after filling.
WARNING!
A fire may result if gasoline is pumped into a
portable container that is inside of a vehicle.
You could be burned. Always place gas
containers on the ground while filling.

21_DPF_OM_EN_USC_t.book Page 196

STARTING AND OPERATING197
NOTE:

Your vehicle is equipped with a DEF injection
system. You may occasionally hear an audible
clicking noise. This is normal operation.

The DEF pump will run for a period of time
after engine shutdown to purge the DEF
system. This is normal operation.
Diesel Exhaust Fluid Storage

Diesel Exhaust Fluid (DEF) is considered a very
stable product with a long shelf life. If DEF is kept
in temperatures between 10° and 90°F (-12°
and 32°C), it will last a minimum of one year.

DEF is subject to freezing at the lowest
temperatures. For example, DEF may freeze
at temperatures at or below 12°F (-11°C).
The system has been designed to operate in
this environment.
NOTE:

When working with DEF, it is important to know that:

Any containers or parts that come into contact
with DEF must be DEF compatible (plastic or
stainless steel). Copper, brass, aluminum, iron or non-stainless steel should be avoided as
they are subject to corrosion by DEF.

If DEF is spilled, it should be wiped up
completely.
Adding Diesel Exhaust Fluid (DEF)
The DEF gauge (located on the instrument
cluster) will display the level of DEF remaining in
the tank Ú
page 90.
NOTE:
Driving conditions (altitude, vehicle speed,
load, etc.) will effect the amount of DEF that
is used in your vehicle.
Another factor is that outside temperature
can affect DEF consumption. In cold condi -
tions, 12°F (-11°C) and below, the DEF
gauge needle can stay on a fixed position and
may not move for extended periods of time.
This is a normal function of the system.
There is an electric heater inside the DEF
tank that automatically works when neces -
sary. And if the DEF supply does freeze, the
truck will operate normally until it thaws. DEF Fill Procedure
NOTE:
For the correct fluid type Ú
page 440.
Remove cap from DEF tank (located on drivers
side of the vehicle or in fuel door).

DEF Filler Cap And Fuel Fill Chassis Cab Models

1 — Diesel Exhaust Fluid (DEF) Fill Location
2 — Diesel Fuel Fill Location
4

21_DPF_OM_EN_USC_t.book Page 197

198STARTING AND OPERATING
(Continued)
NOTE:
The DEF gauge may take up to five seconds
to update after adding a gallon or more of
Diesel Exhaust Fluid (DEF) to the DEF tank.
If you have a fault related to the DEF system,
the gauge may not update to the new level.
See an authorized dealer for service.
The DEF gauge may also not immediately
update after a refill if the temperature of the
DEF fluid is below 39°F (4°C). The DEF tank
heater will possibly warm up the DEF fluid
and allow the gauge to update after a period
of run time. Under very cold conditions, it is
possible that the gauge may not reflect the
new fill level for several drives.
At 40°F (4°C) you could see some increase
in the DEF gauge due to the tank thawing.
The gauge and level sensor are working prop-
erly and is just updating with proper thawed
DEF.
Excessive overfilling of the DEF tank can
result in a MIL lamp/fault code and inaccu -
rate level readings. Refilling With Nozzles
You can fill up at any DEF distributor.
Proceed as follows:
Insert the DEF nozzle in the filler, start
refilling and stop refilling at the first shut-off
(the shut-off indicates that the DEF tank is
full). DO NOT proceed with the refilling, to
prevent spillage of DEF.
Extract the nozzle.
Refilling With Containers
Proceed as follows:
Check the expiration date.
Read the advice for use on the label before
pouring the content of the bottle into the DEF
tank.
After the indication appears on the instru -
ment panel display Ú page 90 fill the DEF
tank with no more than 6 Gallons (22 liters).
CAUTION!
To avoid DEF spillage, and possible
damage to the DEF tank from overfilling, do
not “top off” the DEF tank after filling.
DO NOT OVERFILL. DEF will freeze below
12ºF (-11ºC). The DEF system is designed
to work in temperatures below the DEF
freezing point, however, if the tank is over -
filled and freezes, the system could be
damaged.
When DEF is spilled, clean the area imme -
diately with water and use an absorbent
material to soak up the spills on the ground.
Do not attempt to start your engine if DEF is
accidentally added to the diesel fuel tank
as it can result in severe damage to your
engine, including but not limited to failure
of the fuel pump and injectors.

21_DPF_OM_EN_USC_t.book Page 198