4 Low Indicator Light — If Equipped
Yellow Telltale
Light What It Means
4 Low Indicator Light
This light alerts the driver that the vehicle is in the four-wheel drive LOW mode. The front and
rear driveshafts are mechanically locked together forcing the front and rear wheels to rotate at
the same speed. Low range provides a greater gear reduction ratio to provide increased torque at
the wheels.
Refer to “Four-Wheel Drive Operation — If Equipped” in “Starting And Operating” for further
information on four-wheel drive operation and proper use.
4WD Indicator Light — If Equipped
Yellow Telltale
Light What It Means
4WD Indicator Light
This light alerts the driver that the vehicle is in the four-wheel drive mode, and the front and
rear driveshafts are mechanically locked together forcing the front and rear wheels to rotate at
the same speed.214 UNDERSTANDING YOUR INSTRUMENT PANEL
Units
After pressing the “Units” button on the touchscreen, you
may select each unit of measure independently displayed
in the Instrument Cluster Display, and navigation system
(if equipped). The following selectable units of measure are
listed below:
Setting Name Selectable Options
Speed MPH km/h
Distance mi km
Fuel Consumption MPG (US) MPG (UK) L/100 km km/L
Capacity gal (US) gal (UK) L/100 km L
Pressure psi kpa bar
Temperature °C °F
Power HP (US) HP (UK) kW
Torque lb-ft Nm 4UNDERSTANDING YOUR INSTRUMENT PANEL 239
Units
After pressing the “Units” button on the touchscreen you
may select each unit of measure independently displayed
in the Instrument Cluster Display, and navigation system
(if equipped). The following selectable units of measure are
listed below:
Setting Name Selectable Options
Speed MPH km/h
Distance mi km
Fuel Consumption MPG (US) MPG (UK) L/100 km km/L
Capacity gal (US) gal (UK) L/100 km L
Pressure psi kPa bar
Temperature °C °F
Power HP (US) HP (UK) kW
Torque lb-ft Nm
After the desired setting has been selected, press the back
arrow/Done button on the touchscreen to return to the
previous menu. 258 UNDERSTANDING YOUR INSTRUMENT PANEL
gear range will improve performance and extend transmis-
sion 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 con-
verter clutch engagement. This is done to prevent trans-
mission 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.
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 sig-
nificant additional heat load on the cooling system. Down-
shifting 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 maxi-
mum 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 sec-
tion).
On models with 66RFE transmission, top overdrive gear is
also inhibited until the transmission fluid is warm, and
during extremely cold temperatures (-16°F [-27°C] or be-
low), operation may briefly be limited to first and direct
gears only. 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), operation may briefly be limited to third gear
only. During this condition, the ability of the vehicle to
accelerate under heavily loaded conditions may be re-
duced. In all cases, normal operation will resume once the
transmission temperature has risen to a suitable level. 5STARTING AND OPERATING 331
WARNING!Do not use the “TOW/HAUL” feature when driving in
icy or slippery conditions. The increased engine brak-
ing 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 result-
ing in personal injury or death.
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
accelerations, the clutch automatically disengages. NOTE:
• The torque converter clutch will not engage (and 66RFE-
equipped trucks will not shift to sixth gear), 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 Over-
drive.
• If the vehicle has not been driven for several days, the
first few seconds of operation after shifting the transmis-
sion into gear may seem sluggish. This is due to the fluid
partially draining from the torque converter into the
transmission. This condition is normal and will not
cause damage to the transmission. The torque converter
will refill within five seconds after starting the engine. 5STARTING AND OPERATING 335
POWER TAKE OFF OPERATION — IF EQUIPPED
(CHASSIS CAB ONLY)
This vehicle when equipped with PTO Prep and the
AS66RC 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” or “mobile” mode. The vehicles will be
factory set to the “stationary” mode. To select “mobile”
mode, you will need to enter the commercial vehicle menu
on the instrument cluster screen and select mobile PTO
mode. Details of the PTO selection modes and further PTO
information is available at the Ram Truck Bodybuilders
web site. www.rambodybuilder.com
AS66RC Six-Speed Automatic Transmission Only
The PTO drive gear (part of the AS66RC) operates at torque
converter turbine speed. The turbine speed will be less
than engine speed when the torque converter clutch is not
engaged and will be same as engine speed when the torque
converter clutch is engaged. Stationary Mode
To operate the PTO in this mode the vehicle must meet the
following conditions:
• Transmission in PARK position (vehicles equipped with
automatic transmission.)
• PTO switch has been activated.
• Parking brake applied (vehicles equipped with manual
transmission).
• Brake pedal must not be applied.
• Vehicle engine must be running.
• No vehicle, brake or clutch switch faults present.
• PTO must be correctly installed using the vehicle pro-
vided circuits.
The instrument cluster will display a PTO On message for
five seconds if the above conditions are met. Otherwise, the
instrument cluster will display a message To Operate PTO
Shift To Park indicating what operator action should be
taken to engage the PTO mode.336 STARTING AND OPERATING
The customer has the choice to operate the PTO by utilizing
the cruise control switches or by utilizing a remote control
(provided by the PTO supplier). To operate the feature
using the cruise control switches, the customer must first
activate the PTO switch which will turn on the PTO. In
order to increase or decrease the engine idle speed, to
optimize the PTO function, the “RESUME/ACCEL” and
“DECEL” cruise switches can be used respectively. To
disengage PTO operation and return to “standard vehicle
operation” simply toggle the PTO switch to the OFF
position.
The torque converter clutch (TCC) will automatically en-
gage at engine speeds above 1,200 RPM (engine speed) in
PTO stationary mode. Once engaged, the TCC will remain
applied and will not disengage until the engine speed falls
below 1,000 RPM. TCC engagement is desirable for certain
types of PTO applications (Automatic Transmission Only).
To operate the PTO via a remote switch, the customer must
make sure the above conditions are met. It is vital for
proper operation that the PTO and remote have been
installed correctly, paying special attention to ensure the
vehicle provided wiring has been connected properly. This
is the responsibility of the installer of the PTO and
switches/remote system. It is the responsibility of the PTO manufacturer to ensure that their electrical (switches and
remote) system is compatible with the vehicle’s electrical
architecture and software functionality.
NOTE: Single set speed can be programmed via the PTO
menu on the instrument cluster display. Further details are
available at the Ram Truck Bodybuilders web site located
at rambodybuilder.com
Mobile Mode
To operate the PTO in this mode the vehicle must meet the
following conditions:
• Mobile mode is activated via the menu on the instru-
ment cluster display.
• (ON/OFF) switch has been activated.
• Vehicles with automatic transmission must be in PARK
or DRIVE.
• Parking brake must not be applied.
• Brake pedal must not be applied.
• No vehicle, brake or clutch switch faults present.
• Vehicle engine must be running. 5STARTING AND OPERATING 337
Electronically Shifted Transfer Case (Four-Position
Switch) — If Equipped
The electronic shift transfer case is operated by the 4WD
Control Switch (Transfer Case Switch), which is located on
the instrument panel.
This electronically shifted transfer case provides four mode
positions:
• Two-Wheel Drive High Range (2WD)
• Four-Wheel Drive Lock High Range (4WD LOCK)
• Four-Wheel Drive Low Range (4WD LOW) • Neutral (NEUTRAL)
For additional information on the appropriate use of each
transfer case mode position, see the information below:
2WD
Rear Wheel Drive High Range — This range is for normal
street and highway driving on dry, hard surfaced roads.
4WD LOCK
Four-Wheel Drive Lock High Range — This range maxi-
mizes torque to the front driveshaft, forcing the front and
rear wheels to rotate at the same speed. This range pro-
vides additional traction for loose, slippery road surfaces
only.
4WD LOW
Four-Wheel Drive Low Range — This range provides low
speed four-wheel drive. It maximizes torque to the front
driveshaft, forcing the front and rear wheels to rotate at the
same speed. This range provides additional traction and
maximum pulling power for loose, slippery road surfaces
only. Do not exceed 25 mph (40 km/h).Four-Position/Part Time Transfer Case342 STARTING AND OPERATING