engine JEEP WRANGLER UNLIMITED 2013 Workshop Manual

When frequent transmission shifting occurs (such as
when operating the vehicle under heavy loading condi-
tions, in hilly terrain, traveling into strong head winds, or
while towing heavy trailers), use the Electronic Range
Select (ERS) shift control (refer to “Electronic Range
Select (ERS) Operation” in this section) 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.
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 the current gear until the vehicle is brought to a stop. After the vehicle has stopped, the transmission will
remain in second gear regardless of which forward gear
is selected. PARK, REVERSE, and NEUTRAL will con-
tinue 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 engine OFF.
4. Wait approximately 10 seconds.
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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. 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 shift
lever is in the DRIVE position. For example, if you shift the transmission into 3 (third gear), the transmission will
never shift above third gear, but will shift down into
second and first gear normally.
You can switch between DRIVE and ERS mode at any
vehicle speed. When the shift lever is in the DRIVE
position, the transmission will operate automatically, shift-
ing between all available gears. Tapping the shift lever to
the left (-) will downshift the transmission, activate ERS
mode, display the current gear in the instrument cluster,
and maintain that gear as the top available gear. Once in
ERS mode, tapping the shift lever to the left (-) or right (+)
will change the top available gear.
To exit ERS mode, simply press and hold the shift lever to
the right (+) until “D” is once again displayed in the shift
lever position indicator in the instrument cluster.426 STARTING AND OPERATING

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 an accident
or personal injury.
Screen Display 12 3 4D
Actual Gear(s)
Allowed 1 1-2 1-3 1-4 1-5
NOTE: To select the proper gear position for maximum
deceleration (engine braking), tap the shift lever to the
left (-) repeatedly as the vehicle slows. 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 gear). The transmission will
automatically shift into Overdrive if the following con-
ditions are present:
• the shift lever is in the DRIVE position,
• vehicle speed is sufficiently high, and
• the driver is not heavily pressing the accelerator.
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In the event that additional traction is required, the
transfer case 4H and 4L positions can be used to lock the
front and rear driveshafts together, forcing the front and
rear wheels to rotate at the same speed. This is accom-
plished by simply moving the shift lever to one of these
positions. 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 driveline components.
The “4WD Indicator Light” (located in 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.
NOTE: Do not attempt to shift when only the front or
rear wheels are spinning. The transfer case is not
equipped with a synchronizer, and the front and rear driveshaft speeds must be equal for a shift to take place.
Shifting while only the front or rear wheels are spinning
can cause damage to the transfer case.
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.
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WARNING!
Failure to engage a 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.
TRAC-LOKREAR 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 automati-
cally 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 maxi-
mum traction.
WARNING!
On vehicles equipped with a limited-slip differen-
tial, 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.
432 STARTING AND OPERATING
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extreme situations such as deep snow, mud, steep in-
clines, or sand where additional low speed pulling power
is needed. Vehicle speeds in excess of 25 mph (40 km/h)
should be avoided when in 4L (Low) range.
CAUTION!Do not use 4L (Low) range when operating the
vehicle on dry pavement. Driveline hardware dam-
age can result.
Simultaneous Brake And Throttle Operation
Many off-road driving conditions require the simultane-
ous use of the brake and throttle (two-footed driving).
When climbing rocks, logs, or other stepped objects,
using light brake pressure with light throttle will keep the
vehicle from jerking or lurching. This technique is also
used when you need to stop and restart a vehicle on a
steep incline. Driving In Snow, Mud And Sand
Snow
In heavy snow or for additional control and traction at
slower speeds, shift the transmission into a low gear and
the transfer case into 4L (Low) if necessary. Do not shift to
a lower gear than necessary to maintain headway. Over-
revving the engine can spin the wheels and traction will be
lost. If you start to slow to a stop, try turning your steering
wheel no more than a 1/4 turn quickly back and forth,
while still applying throttle. This will allow the tires to get
a fresh  bite  and help maintain your momentum.
CAUTION!On icy or slippery roads, do not downshift at high
engine RPM or vehicle speeds, because engine brak-
ing may cause skidding and loss of control.
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Before Climbing A Steep Hill
As you approach a hill, consider its grade or steepness.
Determine if it is too steep. Look to see what the traction
is on the hill side trail. Is the trail straight up and down?
What is on top and the other side? Are there ruts, rocks,
branches or other obstacles on the path? Can you safely
recover the vehicle if something goes wrong? If every-
thing looks good and you feel confident, shift the trans-
mission into a lower gear with 4L (Low) engaged, and
proceed with caution, maintaining your momentum as
you climb the hill.
Driving Up Hill
Once you have determined your ability to proceed and
have shifted into the appropriate gear, line your vehicle
up for the straightest possible run. Accelerate with an
easy constant throttle and apply more power as you start
up the hill. Do not race forward into a steep grade; the
abrupt change of grade could cause you to lose control. If the front end begins to bounce, ease off the throttle
slightly to bring all four tires back on the ground. As you
approach the crest of the hill, ease off the throttle and
slowly proceed over the top. If the wheels start to slip as
you approach the crest of a hill, ease off the accelerator
and maintain headway by turning the steering wheel no
more than a 1/4 turn quickly back and forth. This will
provide a fresh  bite  into the surface and will usually
provide enough traction to complete the climb. If you do
not make it to the top, place the vehicle in REVERSE and
back straight down the grade using engine resistance
along with the vehicle brakes.
WARNING!Never attempt to climb a hill at an angle or turn
around on a steep grade. Driving across an incline
increases the risk of a rollover, which may result in
severe injury.444 STARTING AND OPERATING

Driving Downhill
Before driving down a steep hill, you need to determine
if it is too steep for a safe descent. What is the surface
traction? Is the grade too steep to maintain a slow,
controlled descent? Are there obstacles? Is it a straight
descent? Is there plenty of distance at the base of the hill
to regain control if the vehicle descends to fast? If you feel
confident in your ability to proceed, then make sure you
are in 4L (Low) and proceed with caution. Allow engine
braking to control the descent and apply your brakes, if
necessary, but do not allow the tires to lock.
WARNING!Do not descend a steep grade in NEUTRAL. Use
vehicle brakes in conjunction with engine braking.
Descending a grade too fast could cause you to lose
control and be seriously injured. Driving Across An Incline
If at all possible, avoid driving across an incline. If it is
necessary, know your vehicle’s abilities. Driving across
an incline places more weight on the downhill wheels,
which increases the possibilities of a downhill slide or
rollover. Make sure the surface has good traction with
firm and stable soils. If possible, transverse the incline at
an angle heading slightly up or down.
WARNING!Driving across an incline increases the risk of a
rollover , which may result in severe injury.
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If You Stall Or Begin To Lose Headway
If you stall or begin to lose headway while climbing a
steep hill, allow your vehicle to come to a stop and
immediately apply the brake. Restart the engine and shift
into REVERSE. Back slowly down the hill allowing
engine braking to control the descent and apply your
brakes, if necessary, but do not allow the tires to lock.
WARNING!If the engine stalls or you lose headway or cannot
make it to the top of a steep hill or grade, never attempt
to turn around. To do so may result in tipping and
rolling the vehicle, which may result in severe injury.
Always back carefully straight down a hill in RE-
VERSE. Never back down a hill in NEUTRAL using
only the vehicle brakes. Never drive diagonally across
a hill, always drive straight up or down. Driving Through Water
Extreme care should be taken crossing any type of water.
Water crossings should be avoided, if possible, and only
be attempted when necessary in a safe, responsible
manner. You should only drive through areas which are
designated and approved. You should tread lightly and
avoid damage to the environment. You should know
your vehicle’s abilities and be able to recover it if
something goes wrong. You should never stop or shut a
vehicle off when crossing deep water unless you ingested
water into the engine air intake. If the engine stalls, do
not attempt to restart it. Determine if it has ingested
water first. The key to any crossing is low and slow. Shift
into first gear (manual transmission), or DRIVE (auto-
matic transmission), with the transfer case in the 4L
(Low) position and proceed very slowly with a constant
slow speed {3 to 5 mph (5 to 8 km/h) maximum} and
light throttle. Keep the vehicle moving; do not try to446 STARTING AND OPERATING

accelerate through the crossing. After crossing any water
higher than the bottom of the axle differentials, you
should inspect all of the vehicle fluids for signs of water
ingestion.
CAUTION!• Water ingestion into the axles, transmission, trans-
fer case, engine or vehicle interior can occur if you
drive too fast or through too deep of water. Water
can cause permanent damage to engine, driveline
or other vehicle components, and your brakes will
be less effective once wet and/or muddy.
• This vehicle is capable of crossing through water at
a depth of 30 inches (76 cm) at speeds no greater
than 5 mph (8 km/h). Water ingestion can occur
causing damage to your vehicle. Before You Cross Any Type Of Water
As you approach any type of water, you need to deter-
mine if you can cross it safely and responsibly. If neces-
sary, get out and walk through the water or probe it with
a stick. You need to be sure of its depth, approach angle,
current and bottom condition. Be careful of murky or
muddy waters; check for hidden obstacles. Make sure
you will not be intruding on any wildlife, and you can
recover the vehicle if necessary. The key to a safe crossing
is the water depth, current and bottom conditions. On
soft bottoms, the vehicle will sink in, effectively increas-
ing the water level on the vehicle. Be sure to consider this
when determining the depth and the ability to safely
cross.
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