If the transmission temperature exceeds normal operat-
ing limits, the powertrain controller will modify the
transmission 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.
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
temperature as well as vehicle speed. This feature im-
proves 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 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
below), 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 tempera-
tures (-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 loaded414 STARTING AND OPERATING
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 fourth gear (for 66RFE transmission) or third gear (for
AS66RC transmission) 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 transmission. 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 switch to the OFF position.
4. Wait approximately 10 seconds.
5. Restart the engine.
6. Shift into the desired gear range. If the problem is no
longer detected, the transmission will return to normal
operation.
NOTE: Even if the transmission can be reset, we recom-
mend that you visit your authorized dealer at your
earliest possible convenience. Your authorized dealer has
diagnostic equipment to determine if the problem could
recur. 5STARTING AND OPERATING 415
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.
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.
CAUTION!When using ERS for engine braking while descend-
ing steep grades, be careful not to overspeed the
engine. Apply the brakes as needed to prevent en-
gine overspeed. Overdrive Operation
The automatic transmission includes an electronically
controlled Overdrive (fifth and sixth gears). The trans-
mission 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 tem-
perature.
• The engine coolant has reached an adequate tempera-
ture.
• Vehicle speed is sufficiently high.
• The TOW/HAUL switch has not been activated.
• The driver is not heavily pressing the accelerator. 5STARTING AND OPERATING 417
When To Use TOW/HAUL Mode
When driving in hilly areas, towing a trailer, carrying a
heavy load, etc., and frequent transmission shifting oc-
curs, push the TOW/HAUL switch to activate TOW/
HAUL mode. This will improve performance and reduce
the potential for transmission overheating or failure due
to excessive shifting. When operating in TOW/HAUL
mode, transmission upshifts are delayed, and the trans-
mission will automatically downshift (for engine brak-
ing) when the throttle is closed and/or during steady
braking maneuvers.
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 TOW/HAUL Switch418 STARTING AND OPERATING
desired, the switch must be pushed each time the engine
is started.
WARNING!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 possi-
bly resulting 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 automati-
cally 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 con-
verter 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.
• If the vehicle has not been driven for several days, the
first few seconds of operation after shifting the trans-
mission into gear may seem sluggish. This is due to the
fluid partially draining from the torque converter into 5STARTING AND OPERATING 419
the transmission. This condition is normal and will not
cause damage to the transmission. The torque con-
verter will refill within five seconds after starting the
engine.
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 aftermar-
ket 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 com-
mercial vehicle menu on the EVIC/DID 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:
• Be in PARK position (vehicles equipped with auto-
matic transmission.)
• PTO switch has been activated.
• Parking brake applied (vehicles equipped with
manual transmission).
• Brake pedal must not be applied.420 STARTING AND OPERATING
• Vehicle engine must be running.
• No vehicle, brake or clutch switch faults present.
• PTO must be correctly installed using the vehicle
provided circuits.
The Electronic Vehicle Information Center (EVIC) or
Driver Information Display (DID) will display a PTO
On message for five seconds if the above conditions are
met. Otherwise, the EVIC/DID will display a message
To Operate PTO Shift To Park indicating what operator
action should be taken to engage the PTO mode.
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 oper-
ate 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
engage 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 desir-
able 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 5STARTING AND OPERATING 421
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 EVIC/DID screen. Further details are avail-
able at the Ram Truck Bodybuilders web site located
atwww.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 EVIC/
DID screen.
• (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.
• PTO must be correctly installed using the vehicle
provided circuits.
The customer may choose to use the PTO while the
vehicle is moving. To do so, the PTO function must be
activated prior to taking the vehicle out of PARK. This is
accomplished by activating the upfitter-provided PTO
on/off switch. At this point, the customer may place the
vehicle in a forward or reverse gear and have PTO
operation once the vehicle begins to move. To disengage
PTO operation and return to “standard vehicle opera-
tion” simply toggle the on/off switch to the OFF position.422 STARTING AND OPERATING