Six–Speed Automatic Transmission — If Equipped
Chassis Cab models (with automatic transmission) may
use either the AS66RC transmission (which is equipped
with a Power Take-Off (PTO) access cover on the side of the
transmission case), or the 66RFE transmission (which has
no PTO access cover).
The transmission gear position display (located in the
instrument cluster) indicates the transmission gear range.
The gear selector is mounted on the right side of the
steering column. You must press the brake pedal to move
the gear selector out of PARK (refer to “Brake/
Transmission Shift Interlock System” in this section). To
drive, move the gear selector from PARK or NEUTRAL to
the DRIVE position. Pull the gear selector toward you
when shifting into REVERSE or PARK, or when shifting
out of PARK.
The electronically-controlled transmission provides a pre-
cise shift schedule. 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 shift positions. Manual downshifts
can be made using the Electronic Range Select (ERS) shift
control. Pushing the ERS (-/+) switches (on the gear
selector) 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
Electronic
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.
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.
6
STARTING AND OPERATING 247
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
transmission into PARK first, and then apply the parking
brake.
When parking on a hill, apply the parking brake before
shifting the transmission to PARK, otherwise the load on
the transmission locking mechanism may make it difficult
to move the gear selector out of 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.WARNING!
•Never use the PARK position as a substitute 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 gear
selector out of PARK with the brake pedal released.
Make sure the transmission is in PARK before exit-
ing 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 accelerate quickly forward or in re-
verse. 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.
• 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
(Continued)
248 STARTING AND OPERATING
WARNING!(Continued)
the transmission into PARK, turn the engine OFF,
and remove the key fob. When the ignition is in the
LOCK/OFF (key removal) position (or, with Keyless
Enter-N-Go, when the ignition is in the OFF mode),
the transmission is locked in PARK, securing the
vehicle against unwanted movement.
• When leaving 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 unattended 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 trans-
mission gear selector.
• Do not leave the key fob in or near the vehicle (or in
a location accessible to children), and do not leave
the ignition (in a vehicle equipped with Keyless
Enter-N-Go) in the ACC or ON/RUN mode. A child
could operate power windows, other controls, or
move the vehicle.
CAUTION!
• Before moving the transmission gear selector out of
PARK, you must turn the ignition to the ON/RUN
mode, and also press the brake pedal. Otherwise,
damage to the gear selector could result.
• DO NOT race the engine when shifting from PARK
or NEUTRAL into another gear range, as this can
damage the drivetrain.
The following indicators should be used to ensure that you
have properly engaged the transmission into the PARK
position:
• When shifting into PARK, pull the gear selector toward
you and move it all the way counterclockwise until it
stops.
• Release the gear selector and make sure it is fully seated
in the PARK gate.
• Look at the transmission gear position display and
verify that it indicates the PARK position (P).
• With brake pedal released, verify that the gear selector
will not move out of PARK.
6
STARTING AND OPERATING 249
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. The engine may be
started in this range. Apply the parking brake and shift the
transmission into PARK if you must exit the vehicle.
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
(Continued)
CAUTION!(Continued)
Towing” in “Starting And Operating” and “Towing A
Disabled Vehicle” in “In Case Of Emergency” for
further information.
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)
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 transmis-
sion life by reducing excessive shifting and heat buildup.
250 STARTING AND OPERATING
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 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 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.
Transmission Limp Home Mode
Transmission function is monitored electronically for ab-
normal 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
6
STARTING AND OPERATING 251
illuminated. Limp Home Mode allows the vehicle to be
driven to an authorized dealer for service without damag-
ing 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 OFF.
4. Wait approximately 10 seconds.
5. Restart the engine.
6. Shift into the desired gear range. If the problem is nolonger 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 diagnos-
tic equipment to assess the condition of your transmission.
If the transmission cannot be reset, authorized dealer
service is required.Electronic Range Select (ERS) Operation
The Electronic Range Select (ERS) shift control allows the
driver to limit the highest available gear when the trans-
mission is in DRIVE. For example, if you set the transmis-
sion gear limit to 4 (fourth gear), the transmission will not
shift above fourth gear, but will shift through the lower
gears normally.
You can switch between DRIVE and ERS mode at any
vehicle speed. When the gear selector is in the DRIVE
position, the transmission will operate automatically, shift-
ing between all available gears. Tapping the ERS (-) switch
will activate ERS mode, display the current gear in the
instrument cluster, and set that gear as the top available
gear. Once in ERS mode, tapping (-) or (+) will change the
top available gear.
252 STARTING AND OPERATING
4L
Four-Wheel Drive Low Range — This range locks the front
and rear driveshafts together forcing the front and rear
wheels to rotate at the same speed. Additional traction and
maximum pulling power for loose, slippery road surfaces
only. Do not exceed 25 mph (40 km/h).
This transfer case is intended to be driven in the 2H
position for normal street and highway conditions such as
dry, hard surfaced roads.
When additional traction is required, the 4H and 4L
positions can be used to lock the front and rear driveshafts
together and force the front and rear wheels to rotate at the
same speed. This is accomplished by simply moving the
gear selector to the desired positions once the appropriate
speed and gear requirements are met, refer to “Shifting
Procedure – Manually Shifted Transfer Case” in this section
for further information.
The 4H and 4L positions are intended for loose, slippery
road surfaces only. Driving in the 4H and 4L positions on
dry, hard surfaced roads may cause increased tire wear and
damage to the driveline components.
The “Transfer Case Position Indicator Light” in the instru-
ment cluster will alert the driver that the vehicle is infour-wheel drive and that the front and rear driveshafts are
locked together. This light will illuminate when the transfer
case is shifted into either the 4H or 4L position. There is no
light for the 2H or NEUTRAL positions on some models.
When operating your vehicle in 4L, the engine speed is
approximately three times that of the 2H or 4H positions at
a given road speed. Take care not to overspeed the engine
and do not exceed 25 mph (40 km/h).
Proper operation of four-wheel drive vehicles depends on
tires of equal size, type and circumference on each wheel.
Any difference will adversely affect shifting and can cause
damage to the drivetrain.
NOTE:
Do not attempt to make a shift while only the front
or rear wheels are spinning, as this can cause damage to
driveline components.
Because four-wheel drive provides improved traction,
there is a tendency to exceed safe turning and stopping
speeds. Do not go faster than road conditions permit.
NOTE: Delayed shifts out of four-wheel drive may be
experienced due to uneven tire wear, low or uneven tire
pressures, excessive vehicle loading, or cold temperatures.
256 STARTING AND OPERATING
Shifting Procedure — Manually Shifted Transfer
Case
2H To 4H
Shifting between 2H and 4H can be made with the vehicle
stopped or in motion. If the vehicle is in motion, shifts can
be made up to 55 mph (88 km/h). With the vehicle in
motion, the transfer case will engage/disengage faster if
you momentarily release the accelerator pedal after com-
pleting the shift. Apply a constant force when shifting the
transfer case lever.
2H Or 4H To 4L
NOTE:When shifting into or out of 4L some gear noise
may be heard. This noise is normal and is not detrimental
to the vehicle or occupants.
With the vehicle rolling at 2 to 3 mph (3 to 5 km/h), shift
the transmission into NEUTRAL. While the vehicle is
coasting at 2 to 3 mph (3 to 5 km/h), shift the transfer case
lever firmly to the desired position. Do not pause in
transfer case NEUTRAL. NOTE:
•
Pausing in transfer case NEUTRAL in vehicles equipped
with an automatic transmission 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 align-
ment 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 instru-
ment cluster is used to alert the driver that the front axle is
fully engaged and all four wheels are driving.
258 STARTING AND OPERATING