2021 RAM 1500 ECU

STARTING AND OPERATING157
(Continued)
(Continued)
(Continued)
When parking on a hill, apply the parking brake
before shifting the transmission to PARK. As an
added precaution, turn the front wheels toward
the curb on a downhill grade and away from the
curb on an uphill grade.
NOTE:
On four-wheel drive vehicles be sure that the
transfer case is in a drive position.
When exiting the vehicle, always:
Apply the parking brake.
Shift the transmission into PARK.
Turn the engine off.
Remove the key fob from the vehicle.
WARNING!
Never use the PARK position as a substi
-
tute for the parking brake. Always apply the
parking brake fully when exiting the vehicle
to guard against vehicle movement and
possible injury or damage.
Your vehicle could move and injure you and
others if it is not in PARK. Check by trying to
move the transmission gear selector out of
PARK with the brake pedal released. Make
sure the transmission is in PARK before
exiting the vehicle.
The transmission may not engage PARK if
the vehicle is moving. Always bring the
vehicle to a complete stop before shifting to
PARK, and verify that the transmission gear
position indicator solidly indicates PARK (P)
without blinking. Ensure that the vehicle is
completely stopped, and the PARK position
is properly indicated, before exiting the
vehicle.
It is dangerous to shift out of PARK or
NEUTRAL if the engine speed is higher than
idle speed. If your foot is not firmly pressing
the brake pedal, the vehicle could accel -
erate quickly forward or in reverse. You
could lose control of the vehicle and hit
someone or something. Only shift into gear
when the engine is idling normally and your
foot is firmly pressing the brake pedal.
WARNING! (Continued)
Unintended movement of a vehicle could
injure those in or near the vehicle. As with
all vehicles, you should never exit a vehicle
while the engine is running. Before exiting a
vehicle, always come to a complete stop,
then apply the parking brake, shift the
transmission into PARK, and turn the igni -
tion OFF. When the ignition is in the OFF
mode, the transmission is locked in PARK,
securing the vehicle against unwanted
movement.
When exiting the vehicle, always make sure
the ignition is in the OFF mode, remove the
key fob from the vehicle, and lock the
vehicle.
Never leave children alone in a vehicle, or
with access to an unlocked vehicle.
Allowing children to be in a vehicle unat -
tended is dangerous for a number of
reasons. A child or others could be seriously
or fatally injured. Children should be
warned not to touch the parking brake,
brake pedal or the transmission gear
selector.
WARNING! (Continued)
4

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STARTING AND OPERATING173
AXLE LOCK SYSTEM — IF EQUIPPED
This vehicle is equipped with an electronically
locking rear differential. When engaged, this
differential locks the axle shafts forcing the
wheels to spin at an equal rate. The locking of
the rear differential should only be engaged
during low-speed, extreme off-road situations
where one wheel is likely to not be in contact
with the ground. It is not recommended to drive
the vehicle with the differentials locked on
pavement due to the reduced ability to turn and
speed limitations.

Axle Lock Button
The locking rear axle is controlled by the AXLE
LOCK button.
Under normal driving conditions, the rear axle
should be unlocked.
During the command to lock the rear axle, the
indicator light will flash until the axle is locked.
After the lock command has been successfully
executed, the light will remain on solid.
Operating in 4WD LOW the locker can be
engaged up to 40 mph (64 km/h) and will
remain engaged throughout the 4WD LOW
speed range. Operating the locker in 2WD, 4WD AUTO, and
4WD LOCK/HIGH, the locker can be engaged up
to 20 mph (32 km/h). While driving with the
locker engaged, if speed exceeds 25 mph
(40 km/h), the locker will automatically
disengage, but will automatically reengage at
20 mph (32 km/h).
NOTE:
Left to right wheel speed difference may be
necessary to allow the rear axle to fully lock. If
the indicator light is flashing after selecting the
rear axle lock mode, drive the vehicle in a turn
or on loose gravel to expedite the locking action.
The axle locker could become torque locked
due to side to side loads on the rear axle.
Driving slowly while turning the steering wheel
from a left hand turn to a right hand turn or
driving in REVERSE for a short distance may be
required to release the torque lock and unlock
the axles.
To unlock the rear axle; push the AXLE LOCK
button. The AXLE LOCK indicator light will go out
when the rear axle is unlocked.
CAUTION!
Do not lock the rear axle on hard surfaced
roads. The ability to steer the vehicle is
reduced and damage to the drivetrain may
occur when the axle is locked on hard
surfaced roads.
Do not try to lock the rear axle if the vehicle
is stuck and the tires are spinning. You can
damage drivetrain components. Lock the
rear axle before attempting situations or
navigating terrain, which could possibly
cause the vehicle to become stuck.
4

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176STARTING AND OPERATING
TOW/HAUL mode is selected
Accelerator pedal input
Excessive 12 Volt loads
It may be possible to operate the vehicle several
consecutive times in extreme conditions and
not meet all criteria to enable an Autostop state.
TO START THE ENGINE WHILE IN
A
UTOSTOP MODE
While in DRIVE, the engine will start when the
brake pedal is released or the throttle pedal is
pressed and the transmission will automatically
reengage upon engine restart.
Conditions That Will Cause The Engine To Start
Automatically While In Autostop Mode
The engine will start automatically when:
The transmission selector is moved from
DRIVE to REVERSE, NEUTRAL, or PARK
To maintain cabin temperature near the
HVAC settings
HVAC is set to full defrost mode
12 Volt demand requires engine restart
Stop/Start OFF switch is pushed
Transfer case is in 4WD LOW
The emissions system override is present
A Stop/Start system error present
Conditions That Force An Automatic Shift To
Park While In Autostop Mode
The engine will not start automatically and the
transmission will be placed in PARK if:
The driver door is open and brake pedal
released
The driver door is open and the driver seat
belt is unbuckled
The engine hood has been opened
A Stop/Start system error present
The engine may then be restarted by moving the
transmission shift selector out of PARK (e.g. to
DRIVE) or, in some cases, only by a KEY START.
The instrument cluster will display a SHIFT OUT
OF PARK message, or a STOP/START KEY
START REQUIRED message, to indicate which
action is required Ú page 114.
TO MANUALLY TURN OFF THE STOP
S
TART SYSTEM

Stop/Start OFF Switch

Push the Stop/Start OFF switch (located on the
switch bank). The light on the switch will
illuminate. The “STOP/START OFF” message
will appear in the instrument cluster display and
the autostop mode will be disabled
Ú page 114.
NOTE:
The Stop/Start system will reset itself back to
the ON mode every time the ignition is turned
OFF and back ON.

21_DT_OM_EN_USC_t.book Page 176

STARTING AND OPERATING185
The maximum braking applied by ACC is limited;
however, the driver can always apply the brakes
manually, if necessary.
NOTE:
The brake lights will illuminate whenever the
ACC system applies the brakes.
A Proximity Warning will alert the driver if ACC
predicts that its maximum braking level is not
sufficient to maintain the set distance. If this
occurs, a visual alert “BRAKE” will flash in the
instrument cluster display and a chime will
sound while ACC continues to apply its
maximum braking capacity.
NOTE:
The “BRAKE!” Screen in the instrument cluster
display is a warning for the driver to take action
and does not necessarily mean that the
Forward Collision Warning system is applying
the brakes autonomously.
Overtake Aid
When driving with Adaptive Cruise Control (ACC)
engaged, and following a vehicle, the system
will provide an additional acceleration up to the
ACC set speed to assist in passing the vehicle. This additional acceleration is triggered when
the driver utilizes the left turn signal and will
only be active when passing on the left hand
side.
ACC Operation At Stop
If the ACC system brings your vehicle to a
standstill while following the vehicle in front,
your vehicle will resume motion without any
diver intervention if the vehicle in front starts
moving within two seconds.
If the vehicle in front does not start moving
within two seconds of your vehicle coming to a
standstill, the driver will either have to push the
RES (resume) button, or apply the accelerator
pedal to reengage the ACC to the existing set
speed.
NOTE:
After the ACC system holds your vehicle at a
standstill for approximately three consecutive
minutes, the parking brake will be activated,
and the ACC system will be cancelled.
While ACC is holding your vehicle at a standstill,
if the driver seat belt is unbuckled or the driver
door is opened, the parking brake will be
activated, and the ACC system will be cancelled.
Display Warnings And Maintenance
“Wipe Front Radar Sensor In Front Of Vehicle”
Warning
The “ACC/FCW Unavailable Wipe Front Radar
Sensor” warning will display and also a chime
will indicate when conditions temporarily limit
system performance.
This most often occurs at times of poor visibility,
such as in snow or heavy rain. The ACC system
may also become temporarily blinded due to
obstructions, such as mud, dirt or ice. In these
cases, the instrument cluster display will display
“ACC/FCW Unavailable Wipe Front Radar
Sensor” and the system will deactivate.
The “ACC/FCW Unavailable Wipe Front Radar
Sensor” message can sometimes be displayed
while driving in highly reflective areas (i.e. ice
WARNING!
When the ACC system is resumed, the driver
must ensure that there are no pedestrians,
vehicles or objects in the path of the vehicle.
Failure to follow these warnings can result in
a collision and death or serious personal
injury.
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214STARTING AND OPERATING
RIM SIZE
This is the rim size that is appropriate for the tire
size listed.
INFLATION PRESSURE
This is the cold tire inflation pressure for your
vehicle for all loading conditions up to full Gross
Axle Weight Rating (GAWR).
CURB WEIGHT
The curb weight of a vehicle is defined as the
total weight of the vehicle with all fluids,
including vehicle fuel, at full capacity
conditions, and with no occupants or cargo
loaded into the vehicle. The front and rear curb
weight values are determined by weighing your
vehicle on a commercial scale before any
occupants or cargo are added.
LOADING
The actual total weight and the weight of the
front and rear of your vehicle at the ground can
best be determined by weighing it when it is
loaded and ready for operation.
The entire vehicle should first be weighed on a
commercial scale to insure that the Gross
Vehicle Weight Rating (GVWR) has not been exceeded. The weight on the front and rear of
the vehicle should then be determined
separately to be sure that the load is properly
distributed over the front and rear axle.
Weighing the vehicle may show that the Gross
Axle Weight Rating (GAWR) of either the front or
rear axles has been exceeded but the total load
is within the specified GVWR. If so, weight must
be shifted from front to rear or rear to front as
appropriate until the specified weight
limitations are met. Store the heavier items
down low and be sure that the weight is
distributed equally. Stow all loose items
securely before driving.
Improper weight distributions can have an
adverse effect on the way your vehicle steers
and handles and the way the brakes operate.
TRAILER TOWING
In this section you will find safety tips and
information on limits to the type of towing you
can reasonably do with your vehicle. Before
towing a trailer, carefully review this information
to tow your load as efficiently and safely as
possible.
To maintain the New Vehicle Limited Warranty
coverage, follow the requirements and
recommendations in this manual concerning
vehicles used for trailer towing.
COMMON TOWING DEFINITIONS
The following trailer towing related definitions
will assist you in understanding the following
information:
Gross Vehicle Weight Rating (GVWR)
The GVWR is the total allowable weight of your
vehicle. This includes driver, passengers, cargo
and tongue weight. The total load must be
limited so that you do not exceed the GVWR
Ú
page 213.CAUTION!
Do not load your vehicle any heavier than the
GVWR or the maximum front and rear GAWR.
If you do, parts on your vehicle can break, or
it can change the way your vehicle handles.
This could cause you to lose control. Also
overloading can shorten the life of your
vehicle.

21_DT_OM_EN_USC_t.book Page 214

STARTING AND OPERATING221
(Continued)
NOTE:
Trailers may look different during day and night
conditions. In such cases, the trailer may need
to recalibrate.
Some trailers (such as boat trailers) will need to
recalibrate while loaded and unloaded.
NOTE:
The system may not detect a trailer in low
light conditions. In sunny conditions, the
performance may be degraded as shadows
pass over the trailer.
The driver is always responsible for safe oper -
ation of truck and trailer.
The driver is always in control of the truck as
well as the trailer and is responsible for
controlling the throttle and brakes.
The system may not function when the
camera lens is blocked, blurred (covered with
water, snow, ice, dirt, etc) and will not work
unless the tailgate is upright and fully
latched.
TOWING REQUIREMENTS
To promote proper break-in of your new vehicle
drivetrain components, the following guidelines
are recommended.
Perform the maintenance listed in the
Scheduled Servicing section for the proper
maintenance intervals Ú page 395. When
towing a trailer, never exceed the GAWR or
GCWR ratings.
CAUTION!
Do not tow a trailer at all during the first
500 miles (805 km) the new vehicle is driven. The engine, axle or other parts could
be damaged.
Then, during the first 500 miles (805 km) that a trailer is towed, do not drive over
50 mph (80 km/h) and do not make starts
at full throttle. This helps the engine and
other parts of the vehicle wear in at the
heavier loads.
WARNING!
Make certain that the load is secured in the
trailer and will not shift during travel. When
trailering cargo that is not fully secured,
dynamic load shifts can occur that may be
difficult for the driver to control. You could
lose control of your vehicle and have a colli -
sion.
When hauling cargo or towing a trailer, do
not overload your vehicle or trailer. Over -
loading can cause a loss of control, poor
performance or damage to brakes, axle,
engine, transmission, steering, suspension,
chassis structure or tires.
Safety chains must always be used
between your vehicle and trailer. Always
connect the chains to the hook retainers of
the vehicle hitch. Cross the chains under
the trailer tongue and allow enough slack
for turning corners.
4

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230STARTING AND OPERATING
RECREATIONAL TOWING (BEHIND MOTORHOME)
TOWING THIS VEHICLE BEHIND ANOTHER VEHICLE
NOTE:
When towing your vehicle, always follow
applicable state and provincial laws. Contact
state and provincial Highway Safety offices
for additional details.
Vehicles equipped with Active-Level Four
Corner Air Suspension must be placed in
Transport mode before tying them down
(from the body) on a trailer or flatbed truck
Úpage 165. If the vehicle cannot be placed
in Transport mode (for example, engine will
not run), tie-downs must be fastened to the axles (not to the body). Failure to follow these
instructions may cause fault codes to be set
and/or cause loss of proper tie-down tension.
RECREATIONAL TOWING — TWO-WHEEL
D
RIVE MODELS
DO NOT flat tow this vehicle. Damage to the
drivetrain will result.
Recreational towing (for two-wheel drive
models) is allowed ONLY if the rear wheels are
OFF the ground. This may be accomplished using a tow dolly or vehicle trailer. If using a tow
dolly, follow this procedure:
NOTE:
If vehicle is equipped with air suspension,
ensure the vehicle is set to Normal Ride Height.

1. Properly secure the dolly to the tow vehicle,
following the dolly manufacturer's
instructions.

2. Drive the rear wheels onto the tow dolly.
3. Apply the parking brake. Place the transmission in PARK.
Towing Condition Wheels OFF The Ground Two-Wheel Drive Models Four-Wheel Drive Models
Flat Tow NONENOT ALLOWED See InstructionsTransmission in PARK
Transfer case in NEUTRAL (N)
Tow in forward direction
Dolly Tow Front
NOT ALLOWED NOT ALLOWED
Rear OKNOT ALLOWED
On Trailer ALLOKOK

21_DT_OM_EN_USC_t.book Page 230

STARTING AND OPERATING231
(Continued)
4. Properly secure the rear wheels to the dolly, following the dolly manufacturer's
instructions.
5. Turn the ignition OFF.
6. Install a suitable clamping device, designed for towing, to secure the front wheels in the
straight position.
RECREATIONAL TOWING —
F
OUR-WHEEL DRIVE MODELS
NOTE:
The transfer case must be shifted into N
(Neutral) for recreational towing. The transmis -
sion must be shifted into PARK for recreational
towing. Refer to the following for the proper
transfer case N (Neutral) shifting procedure for
your vehicle.
CAUTION!
Towing with the rear wheels on the ground will
cause severe transmission damage. Damage
from improper towing is not covered under
the New Vehicle Limited Warranty.
CAUTION!
DO NOT dolly tow any 4WD vehicle. Towing
with only one set of wheels on the ground
(front or rear) will cause severe transmis -
sion and/or transfer case damage. Tow
with all four wheels either ON the ground, or
OFF the ground (using a vehicle trailer).
Tow only in the forward direction. Towing
this vehicle backwards can cause severe
damage to the transfer case.
Before recreational towing, the transfer
case must be in N (Neutral). To be certain
the transfer case is fully in N (Neutral),
perform the procedure outlined under
“Shifting Into N (Neutral)”. Internal trans -
mission damage will result, if the transfer
case is not in N (Neutral) during towing.
The transmission must be in PARK for
recreational towing.
Ensure that the Electric Park Brake is
released, and remains released, while
being towed.
Towing this vehicle in violation of the above
requirements can cause severe transmis -
sion and/or transfer case damage.
Damage from improper towing is not
covered under the New Vehicle Limited
Warranty.
Do not disconnect the rear driveshaft
because fluid will leak from the transfer
case, causing damage to internal parts.
Do not use a bumper-mounted clamp-on
tow bar on your vehicle. The bumper face
bar will be damaged.
CAUTION! (Continued)
4

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