tow RAM CHASSIS CAB 2019 Service Manual

260 STARTING AND OPERATING
NEUTRAL (N)
Use this range when the vehicle is standing for prolonged
periods with the engine running. The engine may be started
in this range. Apply the parking brake and shift the transmis -
sion into PARK if you must exit the vehicle.
DRIVE (D)
This range should be used for most city and highway
driving. It provides the smoothest upshifts and downshifts, and the best fuel economy. The transmission automatically
upshifts through underdrive first, second, and third gears,
direct fourth gear and overdrive fifth and sixth gears. The
DRIVE position provides optimum driving characteristics
under all normal operating conditions.
When frequent transmission shifting occurs (such as when
operating the vehicle under heavy loading conditions, in
hilly terrain, traveling into strong head winds, or while
towing a heavy trailer), use the Electronic Range Select (ERS)
shift control (refer to “Electronic Range Select (ERS) Opera -
tion” in this section for further information) to select a lower
gear range. Under these conditions, using a lower gear range
will improve performance and extend transmission life by
reducing excessive shifting and heat buildup.
If the transmission temperature exceeds normal operating
limits, the powertrain controller will modify the transmis -
sion shift schedule and expand the range of torque converter
clutch engagement. This is done to prevent transmission
damage due to overheating.
If the transmission becomes extremely hot or is in danger of
overheating, the “Transmission Temperature Warning
Light” may illuminate and the transmission may operate
differently until the transmission cools down.WARNING!
Do not coast in NEUTRAL and never turn off the
ignition to coast down a hill. These are unsafe practices
that limit your response to changing traffic or road
conditions. You might lose control of the vehicle and
have a collision.
CAUTION!
Towing the vehicle, coasting, or driving for any other
reason with the transmission in NEUTRAL can cause
severe transmission damage. Refer to “Recreational
Towing” in “Starting And Operating” and “Towing A
Disabled Vehicle” in “In Case Of Emergency” for further
information.

STARTING AND OPERATING 261
NOTE:
Use caution when operating a heavily loaded vehicle at low
speeds (such as towing a trailer up a steep grade, or in
stop-and-go traffic) during hot weather. In these conditions,
torque converter slip can impose a significant additional heat
load on the cooling system. Downshifting the transmission
to the lowest possible gear (when climbing a grade), or
shifting to NEUTRAL (when stopped in heavy traffic) can
help to reduce this excess heat generation.
During cold temperatures, transmission operation may be
modified depending on engine and transmission tempera -
ture as well as vehicle speed. This feature improves warm up
time of the engine and transmission to achieve maximum
efficiency. Engagement of the torque converter clutch is
inhibited until the transmission fluid is warm (refer to the
“Note” under “Torque Converter Clutch” in this section).
On trucks with AS66RC transmission, fifth and sixth gears
may be inhibited briefly on cold starts below 41°F (5°C), and
during very cold temperatures (-4°F [-20°C] or below), oper -
ation may briefly be limited to third gear only. During this
condition, the ability of the vehicle to accelerate under
heavily loaded conditions may be reduced. In all cases,
normal operation will resume once the transmission
temperature has risen to a suitable level. Transmission Limp Home Mode
Transmission function is monitored electronically for
abnormal conditions. If a condition is detected that could
result in transmission damage, Transmission Limp Home
Mode is activated. In this mode, the transmission remains in
third gear regardless of which forward gear is selected. If an
AS66RC equipped truck enters Limp Home Mode at
highway speeds, it will initially engage fifth gear, until the
vehicle slows to a speed where third gear can be engaged.
PARK, REVERSE, and NEUTRAL will continue to operate.
The Malfunction Indicator Light (MIL) may be illuminated.
Limp Home Mode allows the vehicle to be driven to an
authorized dealer for service without damaging the trans -
mission.
In the event of a momentary problem, the transmission can
be reset to regain all forward gears by performing the
following steps:
1. Stop the vehicle.
2. Shift the transmission into PARK.
3. Turn the ignition OFF.
4. Wait approximately 10 seconds. 5

STARTING AND OPERATING 263
NOTE:
To select the proper gear position for maximum deceleration
(engine braking), simply push and hold the ERS (-) switch.
The transmission will shift to the range from which the
vehicle can best be slowed down.
Overdrive Operation
The automatic transmission includes an electronically
controlled Overdrive (fifth and sixth gears). The transmis -
sion will automatically shift into Overdrive if the following
conditions are present:
• The gear selector is in the DRIVE position.
• The transmission fluid has reached an adequate temperature. • The engine coolant has reached an adequate temperature.
• Vehicle speed is sufficiently high.
• The TOW/HAUL switch has not been activated.
• The driver is not heavily pressing the accelerator.
Torque Converter Clutch
A feature designed to improve fuel economy has been
included in the automatic transmission on your vehicle. A
clutch within the torque converter engages automatically at
calibrated speeds. This may result in a slightly different
feeling or response during normal operation in the upper
gears. When the vehicle speed drops or during some acceler -
ations, the clutch automatically disengages.
NOTE:
• The torque converter clutch will not engage, until the
transmission fluid and engine coolant are warm [usually
after 1 to 3 miles (2 to 5 km) of driving]. Because engine
speed is higher when the torque converter clutch is not
engaged, it may seem as if the transmission is not shifting
properly when cold. This is normal. Using the Electronic
Range Select (ERS) shift control, when the transmission is
sufficiently warm, will demonstrate that the transmission
is able to shift into and out of Overdrive.WARNING!
Do not downshift for additional engine braking on a
slippery surface. The drive wheels could lose their grip
and the vehicle could skid, causing a collision or
personal injury.
CAUTION!
When using ERS for engine braking while descending
steep grades, be careful not to overspeed the engine.
Apply the brakes as needed to prevent engine overspeed. 5

264 STARTING AND OPERATING
• If the vehicle has not been driven for several days, the first
few seconds of operation after shifting the transmission
into gear may seem sluggish. This is due to the fluid
partially draining from the torque converter into the trans -
mission. This condition is normal and will not cause
damage to the transmission. The torque converter will
refill within five seconds after starting the engine.
When To Use TOW/HAUL Mode
When driving in hilly areas, towing a trailer, carrying a
heavy load, etc., and frequent transmission shifting occurs,
push the TOW/HAUL switch to activate TOW/HAUL
mode. This will improve performance and reduce the poten -
tial for transmission overheating or failure due to excessive
shifting. When operating in TOW/HAUL mode, transmis -
sion upshifts are delayed, and the transmission will automat -
ically downshift (for engine braking) when the throttle is
closed and/or during steady braking maneuvers. TOW/HAUL Switch
The “TOW/HAUL Indicator Light” will illuminate in the
instrument cluster to indicate that TOW/HAUL mode has
been activated. Pushing the switch a second time restores
normal operation. Normal operation is always the default at
engine start-up. If TOW/HAUL mode is desired, the switch
must be pushed each time the engine is started.

STARTING AND OPERATING 265
Eight-Speed Automatic Transmission
The transmission is controlled using a rotary electronic gear
selector located on the instrument panel. The transmission
gear range (PRND) is displayed both above the gear selector
and in the instrument cluster. To select a gear range, simply
rotate the gear selector. You must press the brake pedal to
shift the transmission out of PARK (or NEUTRAL, when the
vehicle is stopped or moving at low speeds). To shift past
multiple gear ranges at once (such as PARK to DRIVE),
simply rotate the gear selector to the appropriate detent.
Select the DRIVE range for normal driving. NOTE:
In the event of a mismatch between the gear selector position
and the actual transmission gear (for example, driver selects
PARK while driving), the position indicator will blink
continuously until the selector is returned to the proper posi -
tion, or the requested shift can be completed.
The electronically-controlled transmission adapts its shift
schedule based on driver inputs, along with environmental
and road conditions. The transmission electronics are
self-calibrating; therefore, the first few shifts on a new
vehicle may be somewhat abrupt. This is a normal condition,
and precision shifts will develop within a few hundred miles
(kilometers).
Only shift from DRIVE to PARK or REVERSE when the
accelerator pedal is released and the vehicle is stopped. Be
sure to keep your foot on the brake pedal when shifting
between these gears.
The transmission gear selector has only PARK, REVERSE,
NEUTRAL, and DRIVE positions. Manual downshifts can be
made using the Electronic Range Select (ERS) shift control.
Pressing the GEAR-/GEAR+ switches (on the steering
wheel) while in the DRIVE position will select the highest
available transmission gear, and will display that gear limit
in the instrument cluster as 1, 2, 3, etc. Refer to “ElectronicWARNING!
Do not use the “TOW/HAUL” feature when driving in
icy or slippery conditions. The increased engine braking
can cause the rear wheels to slide, and the vehicle to
swing around with the possible loss of vehicle control,
which may cause an accident possibly resulting in
personal injury or death.
5

266 STARTING AND OPERATING
Range Select (ERS) Operation” in this section for further
information. Some models will display both the selected gear
limit, and the actual current gear, while in ERS mode.
Electronic Transmission Gear Selector
Gear Ranges
Do not depress the accelerator pedal when shifting from
PARK or NEUTRAL into another gear range.
NOTE:
After selecting any gear range, wait a moment to allow the
selected gear to engage before accelerating. This is especially
important when the engine is cold. PARK (P)
This range supplements the parking brake by locking the
transmission. The engine can be started in this range. Never
attempt to use PARK while the vehicle is in motion. Apply
the parking brake when exiting the vehicle in this range.
When parking on a level surface, you may shift the transmis -
sion into PARK first, and then apply the parking brake.
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.

268 STARTING AND OPERATING
The following indicators should be used to ensure that you
have properly engaged the transmission into the PARK posi -
tion:
• Look at the transmission gear position display and verify
that it indicates the PARK position (P), and is not blinking.
• With brake pedal released, verify that the gear selector will
not move out of PARK.
REVERSE (R)
This range is for moving the vehicle backward. Shift into
REVERSE only after the vehicle has come to a complete stop. NEUTRAL (N)
Use this range when the vehicle is standing for prolonged
periods with the engine running. Apply the parking brake
and shift the transmission into PARK if you must exit the
vehicle.CAUTION!
• DO NOT race the engine when shifting from PARK or
NEUTRAL into another gear range, as this can damage
the drivetrain.
• Before moving the transmission gear selector out of
PARK, you must start the engine, and also press the
brake pedal. Otherwise, damage to the gear selector
could result. WARNING!
Do not coast in NEUTRAL and never turn off the
ignition to coast down a hill. These are unsafe practices
that limit your response to changing traffic or road
conditions. You might lose control of the vehicle and
have a collision.
CAUTION!
Towing the vehicle, coasting, or driving for any other
reason with the transmission in NEUTRAL can cause
severe transmission damage. Refer to “Recreational
Towing” in “Starting And Operating” and “Towing A
Disabled Vehicle” in “In Case Of Emergency” for further
information.

STARTING AND OPERATING 269
DRIVE (D)
This range should be used for most city and highway
driving. It provides the smoothest upshifts and downshifts,
and the best fuel economy. The transmission automatically
upshifts through all forward gears. The DRIVE position
provides optimum driving characteristics under all normal
operating conditions.
When frequent transmission shifting occurs (such as when
operating the vehicle under heavy loading conditions, in
hilly terrain, traveling into strong head winds, or while
towing a heavy trailer), select TOW/HAUL mode or use the
Electronic Range Select (ERS) shift control (refer to "Elec -
tronic Range Select (ERS) Operation" in this section for
further information) to select a lower gear range. Under
these conditions, using a lower gear range will improve
performance and extend transmission life by reducing exces -
sive shifting and heat buildup.
During extremely cold temperatures (-22°F [-30°C] or
below), transmission operation may be modified depending
on engine and transmission temperature as well as vehicle
speed. Normal operation will resume once the transmission
temperature has risen to a suitable level. Transmission Limp Home Mode
Transmission function is monitored electronically for
abnormal conditions. If a condition is detected that could
result in transmission damage, Transmission Limp Home
Mode is activated. In this mode, the transmission may
operate only in certain gears, or may not shift at all. Vehicle
performance may be severely degraded and the engine may
stall. In some situations, the transmission may not re-engage
if the engine is turned off and restarted. The Malfunction
Indicator Light (MIL) may be illuminated. A message in the
instrument cluster will inform the driver of the more serious
conditions, and indicate what actions may be necessary.
In the event of a momentary problem, the transmission can
be reset to regain all forward gears by performing the
following steps:
NOTE:
In cases where the instrument cluster message indicates the
transmission may not re-engage after engine shutdown,
perform this procedure only in a desired location (prefer -
ably, at an authorized dealer).
1. Stop the vehicle.
2. Shift the transmission into PARK, if possible. If not, shift
the transmission to NEUTRAL. 5

STARTING AND OPERATING 271
To exit ERS mode, simply push and hold the GEAR+ switch
until the gear limit display disappears from the instrument
cluster.
When to Use TOW/HAUL Mode
When driving in hilly areas, towing a trailer, carrying a
heavy load, etc., and frequent transmission shifting occurs,
push the TOW/HAUL switch to activate TOW/HAUL
mode. This will improve performance and reduce the poten -
tial for transmission overheating or failure due to excessive
shifting. TOW/HAUL Switch
The “TOW/HAUL Indicator Light” will illuminate in the
instrument cluster to indicate that TOW/HAUL mode has
been activated. Pushing the switch a second time restores
normal operation. Normal operation is always the default at
engine start-up. If TOW/HAUL mode is desired, the switch
must be pushed each time the engine is started.WARNING!
Do not downshift for additional engine braking on a
slippery surface. The drive wheels could lose their grip
and the vehicle could skid, causing a collision or
personal injury.
5

272 STARTING AND OPERATING
FOUR-WHEEL DRIVE OPERATION — IF EQUIPPED
Four-wheel drive trucks are equipped with either a manu -
ally shifted transfer case or an electronically shifted transfer
case. Refer to the operating instructions for your transfer
case, located in this section for further information. Four-Position Electronically Shifted Transfer Case —
If Equipped
This is an electronic shift transfer case and is operated by the
4WD Control Switch (Transfer Case Switch), which is
located on the instrument panel.
Four-Position Transfer CaseWARNING!
Do not use the “TOW/HAUL” feature when driving in
icy or slippery conditions. The increased engine braking
can cause the rear wheels to slide, and the vehicle to
swing around with the possible loss of vehicle control,
which may cause an accident possibly resulting in
personal injury or death.