2021 JEEP WRANGLER UNLIMITED engine

145
Eight–Speed Automatic Transmission
Your vehicle is equipped with a fuel efficient
8 speed transmission. The gear selector is
located in the center console.Transmission Gear Selector
The transmission gear selector provides
PARK, REVERSE, NEUTRAL, DRIVE and
MANUAL (AutoStick) shift positions. Manual
shifts can be made using the AutoStick shift
control. Toggling the gear selector forward (-)
or rearward (+) while in the MANUAL (Auto -
Stick) position (beside the DRIVE position)
will manually select the transmission gear,
and will display the current gear in the
instrument cluster. Refer to "AutoStick" in
this section for further information. NOTE:
If the gear selector cannot be moved to the
PARK, REVERSE, or NEUTRAL position
(when pushed forward), it is probably in the
AutoStick (+/-) position (beside the DRIVE
position). In AutoStick mode, the transmis
-
sion gear (1, 2, 3, etc.) is displayed in the
instrument cluster. Move the gear selector to
the right (into the DRIVE [D] position) for
access to PARK, REVERSE, and NEUTRAL.
AutoStick
AutoStick is a driver-interactive transmission
feature providing manual shift control, giving
you more control of the vehicle. AutoStick
allows you to maximize engine braking, elim -
inate undesirable upshifts and downshifts,
and improve overall vehicle performance.
This system can also provide you with more
control during passing, city driving, cold slip -
pery conditions, mountain driving, trailer
towing, and many other situations. Operation

To activate AutoStick mode, move the gear
selector into the MANUAL (M) position (beside
the DRIVE position). The current transmission
gear will be displayed in the instrument cluster.
In AutoStick mode, you can use the gear
selector (in the MANUAL position) to manually
shift the transmission. Tapping the gear
selector forward (-) while in the MANUAL (M)
position will downshift the transmission to the
next lower gear. Tapping the selector rearward
(+) will command an upshift.

In AutoStick mode, the transmission will
shift up or down when (+/-) is manually
selected by the driver, unless an engine
lugging or overspeed condition would result.
It will remain in the selected gear until
another upshift or downshift is chosen,
except as described below.
The transmission will automatically down
-
shift as the vehicle slows (to prevent
engine lugging) and will display the
current gear.
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STARTING AND OPERATING
146
The transmission will automatically down-
shift to FIRST gear when coming to a stop.
After a stop, the driver should manually
upshift (+) the transmission as the vehicle
is accelerated.
You can start out, from a stop, in FIRST or
SECOND gear (or THIRD gear, in 4L
range). Tapping (+) (at a stop) will allow
starting in SECOND gear. Starting out in
SECOND or THIRD gear can be helpful in
snowy or icy conditions.
If a requested downshift would cause the
engine to over-speed, that shift will not
occur.
The system will ignore attempts to upshift
at too low of a vehicle speed.
Holding the gear selector in the (-) posi -
tion will downshift the transmission to the
lowest gear possible at the current speed.
Transmission shifting will be more notice-
able when AutoStick is enabled.
The system may revert to automatic shift
mode if a fault or overheat condition is
detected. NOTE:
When Hill Descent Control is enabled, Auto
-
Stick is not active.
To disengage AutoStick mode, return the
gear selector to the DRIVE position. You can
shift in or out of the AutoStick position at any
time without taking your foot off the acceler -
ator pedal.
FOUR–WHEEL DRIVE
OPERATION
Four-Position Transfer Case
Four-Wheel Drive Gear Selector
The transfer case provides four mode posi -
tions:
2H (Two-Wheel Drive High Range)
4H (Four-Wheel Drive High Range)
N (Neutral)
4L (Four-Wheel Drive Low Range)
For additional information on the appropriate
use of each transfer case mode position, see
the information below:
2H
Two-Wheel Drive High Range — This range is
for normal street and highway driving on dry,
hard surfaced roads.
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.
WARNING!
Failure to engage a transfer case position
completely can cause transfer case
damage or loss of power and vehicle
control. You could have a collision. Do not
drive the vehicle unless the transfer case
is fully engaged.
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147
4H
Four-Wheel Drive High Range — This range
maximizes torque to the front driveshaft,
forcing the front and rear wheels to rotate at
the same speed. This range provides addi-
tional traction for loose, slippery road
surfaces only.
NEUTRAL (N)
Neutral — This range disengages both the
front and rear driveshafts from the power -
train. To be used for flat towing behind
another vehicle.
Refer to “Recreational Towing” in this
chapter for further information. 4L
Four-Wheel Drive Low Range — This range
provides low speed four-wheel drive. It maxi
-
mizes 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).
The transfer case is intended to be driven in
the 2H position for normal street and
highway conditions, such as hard-surfaced
roads.
In the event that additional traction is
required, the transfer case 4H and 4L posi -
tions can be used to lock the front and rear
driveshafts together, forcing the front and
rear wheels to rotate at the same speed. The
4H and 4L positions are intended for loose,
slippery road surfaces only and not intended
for normal driving. Driving in the 4H and 4L
positions on hard-surfaced roads will cause
increased tire wear and damage to the drive -
line components. Refer to “Shifting Proce -
dures” in this section for further information
on shifting into 4H or 4L. The instrument cluster alerts the driver that
the vehicle is in four-wheel drive, and the
front and rear driveshafts are locked
together. The light will illuminate when the
transfer case is shifted into the 4H position.
When operating your vehicle in 4L, the
engine speed will be approximately three
times (four times for Rubicon models) that of
the 2H or 4H positions at a given road speed.
Take care not to overspeed the engine.
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 cause
damage to the transfer case.
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.
Shifting Procedures
2H To 4H Or 4H To 2H
Shifting between 2H and 4H can be made
with the vehicle stopped or in motion. The
preferred shifting speed would be 0 to
45 mph (72 km/h). With the vehicle in
motion, the transfer case will engage/disen
-
WARNING!
You or others could be injured or killed if
you leave the vehicle unattended with the
transfer case in the NEUTRAL (N) position
without first fully engaging the parking
brake. The transfer case NEUTRAL (N)
position disengages both the front and rear
driveshafts from the powertrain, and will
allow the vehicle to roll, even if the
automatic transmission is in PARK. The
parking brake should always be applied
when the driver is not in the vehicle.
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STARTING AND OPERATING
150
In the event that additional traction is
required, the transfer case 4H and 4L posi-
tions can be used to lock the front and rear
driveshafts together, forcing the front and
rear wheels to rotate at the same speed. The
4H and 4L positions are intended for loose,
slippery road surfaces only and not intended
for normal driving. Driving in the 4H and 4L
positions on hard-surfaced roads will cause
increased tire wear and damage to the drive -
line components. Refer to “Shifting Proce -
dures” in this section for further information
on shifting into 4H or 4L.
The instrument cluster alerts the driver that
the vehicle is in four-wheel drive, and the
front and rear driveshafts are locked
together. The light will illuminate when the
transfer case is shifted into the 4H position.
When operating your vehicle in 4L, the
engine speed will be approximately three
times (four times for Rubicon models) that of
the 2H or 4H positions at a given road speed.
Take care not to overspeed the engine.
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 cause
damage to the transfer case. 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.
Shifting Procedures
2H To 4H Auto Or 4H Auto To 2H
Shifting between 2H and 4H Auto can be
made with the vehicle stopped or in motion.
The preferred shifting speed would be 0 to
45 mph (72 km/h). With the vehicle in
motion, the transfer case will engage/disen
-
gage faster if you momentarily release the
accelerator pedal after completing the shift.
Do not accelerate while shifting the transfer
case. Apply a constant force when shifting
the transfer case lever.
2H/4H Auto To 4H Part Time Or 4H Part Time To
2H/4H Auto
Shifting between 2H/4H AUTO to 4H PART
TIME can be made with the vehicle stopped
or in motion. The preferred shifting speed
would be 0 to 45 mph (72 km/h). With the
vehicle in motion, the transfer case will
engage/disengage faster if you momentarily
release the accelerator pedal after
completing the shift. Do not accelerate while shifting the transfer case. Apply a constant
force when shifting the transfer case lever.
NOTE:
Do not attempt to make a shift while only
the front or rear wheels are spinning. The
front and rear driveshaft speeds must be
equal for the shift to take place. Shifting
while only the front or rear wheels are
spinning can cause damage to the transfer
case.
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.
Shifting effort will increase with speed,
this is normal.
During cold weather, you may experience
increased effort in shifting until the transfer
case fluid warms up. This is normal.
4H Part Time/4H Auto To 4L Or 4L To 4H Part Time/
4H Auto
With the vehicle rolling at 2 to 3 mph (3 to
5 km/h), shift the transmission into
NEUTRAL (N). While the vehicle is coasting
at 2 to 3 mph (3 to 5 km/h), shift the
transfer case lever firmly to the desired posi -
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151
tion. Do not pause with the transfer case in
N (Neutral). Once the shift is completed,
place the transmission into DRIVE.
NOTE:
Shifting into or out of 4L is possible with the
vehicle completely stopped; however, diffi-
culty may occur due to the mating teeth not
being properly aligned. Several attempts may
be required for clutch teeth alignment and
shift completion to occur. The preferred
method is with the vehicle rolling at 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).Trac-Lok Rear Axle — If Equipped
The Trac-Lok rear axle provides a constant
driving force to both rear wheels and reduces
wheel spin caused by the loss of traction at
one driving wheel. If traction differs between
the two rear wheels, the differential automat -
ically proportions the usable torque by
providing more torque to the wheel that has
traction.
Trac-Lok is especially helpful during slippery
driving conditions. With both rear wheels on
a slippery surface, a slight application of the
accelerator will supply maximum traction.
Axle Lock (Tru-Lok) — Rubicon Models

The AXLE LOCK switch is located on the instru -
ment panel (to the right of the steering column).

Axle Lock Switch Panel
This feature will only activate when the
following conditions are met:
Ignition in RUN position, vehicle in 4L
(Low) range.

Vehicle speed should be 10 mph (16 km/h)
or less.

Both right and left wheels on axle are at
the same speed.
To activate the system, push the AXLE LOCK
switch down to lock the rear axle only (the
“REAR ONLY” will illuminate), push the
switch up to lock the front axle and rear axle
WARNING!
Failure to engage a transfer case position
completely can cause transfer case
damage or loss of power and vehicle
control. You could have a collision. Do not
drive the vehicle unless the transfer case
is fully engaged.
WARNING!
On vehicles equipped with a limited-slip
differential, never run the engine with one
rear wheel off the ground. The vehicle may
drive through the rear wheel remaining on
the ground and cause you to lose control of
your vehicle.
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153
NOTE:
The stabilizer/sway bar may be torque locked
due to left and right suspension height
differences. This condition is due to driving
surface differences or vehicle loading. In
order for the stabilizer/sway bar to discon-
nect/reconnect, the right and left halves of
the bar must be aligned. This alignment may
require that the vehicle be driven onto level
ground or rocked from side to side.
To return to on-road mode, push the SWAY
BAR switch again.
STOP/START SYSTEM —
AUTOMATIC TRANSMISSION
(IF EQUIPPED)

The Stop/Start function is developed to
reduce fuel consumption. The system will
stop the engine automatically during a
vehicle stop if the required conditions are
met. Releasing the brake pedal or pressing
the accelerator pedal will automatically
re-start the engine.
Engine Stop/Start (ESS) vehicles have been
upgraded with a heavy duty starter,
enhanced battery, and other upgraded
engine parts, to handle the additional engine
starts.
NOTE:
It is recommended that the Stop/Start
System be disabled during off-road use. Secondary Battery
Your vehicle may be equipped with a
secondary battery used to power the Stop/
Start system and the 12 Volt vehicle elec
-
trical system. The secondary battery is
located behind the wheel well for the front
driver’s side wheel.
Battery Locations
WARNING!
If the stabilizer/sway bar will not return to
on-road mode, the “Sway Bar Indicator
Light” will flash in the instrument cluster
and vehicle stability may be reduced. Do
not attempt to drive the vehicle over
18 mph (29 km/h). Driving faster than
18 mph (29 km/h) with a disconnected
stabilizer/sway bar may contribute to the
loss of vehicle control, which could result
in serious injury.
1 — Primary Battery
2 — Secondary Battery
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154
Automatic Mode
The Stop/Start feature is enabled
after every normal customer engine
start. At that time, the system will
go into STOP/START READY and if
all other conditions are met, can go into a
STOP/START AUTOSTOP ACTIVE
“Autostop” mode.
To Activate The Autostop Mode, The Following
Must Occur:
The system must be in STOP/START
READY state. A STOP/START READY
message will be displayed in the instru -
ment cluster display within the Stop/Start
section. Refer to “Instrument Cluster” in
“Getting To Know Your Instrument Panel”
in your Owner’s Manual for further infor -
mation.
The vehicle must be completely stopped.
The shifter must be in a forward gear and
the brake pedal depressed.
The engine will shut down, the tachometer
will move to the zero position and the Stop/
Start telltale will illuminate indicating you
are in Autostop. Customer settings will be
maintained upon return to an engine running
condition. Refer to the “Stop/Start System” in the
“Starting And Operating” section located in
your Owner’s Manual for further information.
Possible Reasons The Engine Does Not
Autostop
Prior to engine shut down, the system will
check many safety and comfort conditions to
see if they are fulfilled. Detailed information
about the operation of the Stop/Start system
may be viewed in the instrument cluster
display Stop/Start Screen. In the following
situations, the engine will not stop:
Driver’s seat belt is not buckled.
Driver’s door is not closed.
Battery temperature is too warm or cold.
Battery charge is low.
The vehicle is on a steep grade.
Cabin heating or cooling is in process and
an acceptable cabin temperature has not
been achieved.
HVAC is set to full defrost mode at a high
blower speed.
HVAC set to MAX A/C.
Engine has not reached normal operating
temperature.
Engine temperature too high.
The transmission is not in a forward gear.
Hood is open.
Transfer case is in 4L or Neutral.
Brake pedal is not pressed with sufficient
pressure.
Other Factors Which Can Inhibit Autostop
Include:
Accelerator pedal input.
Vehicle speed threshold not achieved from
previous auto-stop.
Steering angle beyond threshold. (ESS
Models Only)
ACC is on and speed is set.
Vehicle is at high altitude.
System fault present.
It may be possible for the vehicle to be driven
several times without the Stop/Start system
going into a STOP/START READY state
under more extreme conditions of the items
listed above.
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155
To Start The Engine While In Autostop
Mode
While in a forward gear, the engine will start
when the brake pedal is released or the
throttle pedal is depressed. The transmission
will automatically re-engage upon engine
restart.
Conditions That Will Cause The Engine To Start
Automatically While In Autostop Mode:
The transmission selector is moved out of
DRIVE.
To maintain cabin temperature comfort.
Actual cabin temperature is significantly
different than temperature set on Auto
HVAC.
HVAC is set to full defrost mode.
HVAC system temperature or fan speed is
manually adjusted.
Battery voltage drops too low.
Low brake vacuum (e.g. after several brake
pedal applications).
Stop/Start OFF switch is pushed.
A Stop/Start system error occurs.
STOP/START AUTO STOP ACTIVE time
exceeds 5 minutes.
4WD system is put into 4L or Neutral
mode.
Steering wheel is turned beyond
threshold. (ESS Models Only)
To Manually Turn Off The Stop/Start
System
1. Push the Stop/Start OFF switch (located
on the switch bank). The light on the
switch will illuminate.
Stop/Start OFF switch
2. The “STOP/START OFF” message will appear in instrument cluster display
within the Stop/Start section. Refer to
“Instrument Cluster” in “Getting To Know Your Instrument Panel” in your
Owner’s Manual for further information.
3. At the next vehicle stop (after turning off the Stop/Start system), the engine will
not be stopped.
4. The Stop/Start system will reset itself back to an ON condition every time the
ignition is turned off and back on.To Manually Turn On The Stop/Start
System
Push the Stop/Start OFF switch (located on
the switch bank). The light on the switch will
turn off.

For complete details on the Stop/Start System
refer to the “Stop/Start System” in the
“Starting And Operating” section located in
your Owner’s Manual for further information.

System Malfunction
If there is a malfunction in the Stop/Start
system, the system will not shut down the
engine. A “SERVICE STOP/START SYSTEM”
message will appear in the instrument
cluster display. Refer to “Instrument Cluster
Display“ in “Getting to Know Your Instru -
ment Panel” for further information.
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