2021 JEEP WRANGLER UNLIMITED service

SERVICING AND MAINTENANCE
226
DEALER SERVICE
An authorized dealer has the qualified
service personnel, special tools, and equip-
ment to perform all service operations in an
expert manner. Service Manuals are avail -
able which include detailed service informa -
tion for your vehicle. Refer to these Service
Manuals before attempting any procedure
yourself.
NOTE:
Intentional tampering with emissions control
systems may void your warranty and could
result in civil penalties being assessed
against you.
Windshield Wiper Blades
Clean the rubber edges of the wiper blades
and the windshield periodically with a
sponge or soft cloth and a mild nonabrasive
cleaner. This will remove accumulations of
salt or road film.
Operation of the wipers on dry glass for long
periods may cause deterioration of the wiper
blades. Always use washer fluid when using
the wipers to remove salt or dirt from a dry
windshield.
Avoid using the wiper blades to remove frost
or ice from the windshield. Keep the blade
rubber out of contact with petroleum prod -
ucts such as engine oil, gasoline, etc.
NOTE:
Life expectancy of wiper blades varies
depending on geographical area and
frequency of use. Poor performance of
blades may be present with chattering,
marks, water lines or wet spots. If any of
these conditions are present, clean the wiper
blades or replace as necessary. The wiper blades and wiper arms should be
inspected periodically, not just when wiper
performance problems are experienced. This
inspection should include the following
points:
Wear or uneven edges
Foreign material
Hardening or cracking
Deformation or fatigue
If a wiper blade or wiper arm is damaged,
replace the affected wiper arm or blade with
a new unit. Do not attempt to repair a wiper
arm or blade that is damaged.
WARNING!
You can be badly injured working on or
around a motor vehicle. Only do service
work for which you have the knowledge
and the proper equipment. If you have any
doubt about your ability to perform a
service job, take your vehicle to a
competent mechanic.
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229
(Continued)
Under normal operating conditions, the cata-
lytic converter will not require maintenance.
However, it is important to keep the engine
properly tuned to ensure proper catalyst
operation and prevent possible catalyst
damage.
NOTE:
Intentional tampering with emissions control
systems can result in civil penalties being
assessed against you.
In unusual situations involving grossly
malfunctioning engine operation, a
scorching odor may suggest severe and
abnormal catalyst overheating. If this occurs,
stop the vehicle, turn off the engine and
allow it to cool. Service, including a tune-up
to manufacturer's specifications, should be
obtained immediately.
To minimize the possibility of catalytic
converter damage:
Do not interrupt the ignition when the
transmission is in gear and the vehicle is
in motion.
Do not try to start the vehicle by pushing
or towing the vehicle.
Do not idle the engine with any ignition
components disconnected or removed,
such as when diagnostic testing, or for
prolonged periods during very rough idle or
malfunctioning operating conditions.
Cooling System

A hot exhaust system can start a fire if you
park over materials that can burn. Such
materials might be grass or leaves coming
into contact with your exhaust system. Do not
park or operate your vehicle in areas where
your exhaust system can contact anything
that can burn.

CAUTION!

The catalytic converter requires the use of
unleaded fuel only. Leaded gasoline will
destroy the effectiveness of the catalyst as an
emissions control device and may seriously
reduce engine performance and cause
serious damage to the engine.
Damage to the catalytic converter can result
if your vehicle is not kept in proper operating
condition. In the event of engine malfunc -
tion, particularly involving engine misfire or
other apparent loss of performance, have your
vehicle serviced promptly. Continued opera-
tion of your vehicle with a severe malfunction
could cause the converter to overheat,
resulting in possible damage to the converter
and vehicle.

WARNING! (Continued)
WARNING!
You or others can be badly burned by hot
engine coolant (antifreeze) or steam
from your radiator. If you see or hear
steam coming from under the hood, do
not open the hood until the radiator has
had time to cool. Never open a cooling
system pressure cap when the radiator or
coolant bottle is hot.
Keep hands, tools, clothing, and jewelry
away from the radiator cooling fan when
the hood is raised. The fan starts auto-
matically and may start at any time,
whether the engine is running or not.
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SERVICING AND MAINTENANCE
230(Continued)
Coolant Checks
Check the engine and, intercooler (if
equipped) coolant (antifreeze) protection
every 12 months (before the onset of
freezing weather, where applicable). If the
engine and, intercooler (if equipped) is dirty
or rusty in appearance, the system should be
drained, flushed and refilled with fresh OAT
coolant (conforming to MS.90032) by an
authorized dealer. Check the front of the A/C
condenser (if equipped) or radiator for any
accumulation of bugs, leaves, etc. If dirty,
clean by gently spraying water from a garden
hose vertically down the face of the A/C
condenser (if equipped) or the back of the
radiator core.Check the engine and, intercooler (if
equipped) cooling system hoses for brittle
rubber, cracking, tears, cuts, and tightness
of the connection at the coolant recovery
bottle and radiator. Inspect the entire system
for leaks. DO NOT REMOVE THE COOLANT
PRESSURE CAP WHEN THE COOLING
SYSTEM IS HOT.
Brake System
In order to ensure brake system perfor
-
mance, all brake system components should
be inspected periodically. Refer to the
“Maintenance Plan” in this section for the
proper maintenance intervals.
Fluid Level Check — Brake Master Cylinder
The fluid level of the master cylinder should
be checked whenever the vehicle is serviced,
or immediately if the brake system warning
light is on. If necessary, add fluid to bring
level within the designated marks on the side
of the reservoir of the brake master cylinder.
Be sure to clean the top of the master
cylinder area before removing cap. With disc
brakes, fluid level can be expected to fall as
the brake pads wear. Brake fluid level should
be checked when pads are replaced. If the
brake fluid is abnormally low, check the
system for leaks.
Refer to “Fluids And Lubricants” in “Tech -
nical Specifications” for further information.When working near the radiator cooling
fan, turn the ignition to the OFF mode.
The fan is temperature controlled and
can start at any time the ignition is in the
ON mode.
WARNING! (Continued)
WARNING!
Riding the brakes can lead to brake failure
and possibly a collision. Driving with your
foot resting or riding on the brake pedal
can result in abnormally high brake
temperatures, excessive lining wear, and
possible brake damage. You would not
have your full braking capacity in an
emergency. WARNING!
Use only manufacturer's recommended
brake fluid. Refer to “Fluids And Lubri -
cants” in “Technical Specifications” for
further information. Using the wrong
type of brake fluid can severely damage
your brake system and/or impair its
performance. The proper type of brake
fluid for your vehicle is also identified on
the original factory installed hydraulic
master cylinder reservoir.
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SERVICING AND MAINTENANCE
232
(Continued)
Fluid Level Check
The fluid level is preset at the factory and
does not require adjustment under normal
operating conditions. Routine fluid level
checks are not required; therefore the trans-
mission has no dipstick. An authorized
dealer can check your transmission fluid
level using special service tools. If you notice
fluid leakage or transmission malfunction,
visit an authorized dealer immediately to
have the transmission fluid level checked.
Operating the vehicle with an improper fluid
level can cause severe transmission damage.
RAISING THE VEHICLE
In the case where it is necessary to raise the
vehicle, go to an authorized dealer or service
station.
TIRES
Tires — General Information
Tire Pressure
Proper tire inflation pressure is essential to
the safe and satisfactory operation of your
vehicle. Four primary areas are affected by
improper tire pressure:
Safety
Fuel Economy
Tread Wear
Ride Comfort and Vehicle Stability
Safety Both underinflation and overinflation affect
the stability of the vehicle and can produce
a feeling of sluggish response or over respon
-
siveness in the steering.
NOTE:
Unequal tire pressures from side to side
may cause erratic and unpredictable
steering response.
Unequal tire pressure from side to side
may cause the vehicle to drift left or right.
Fuel Economy

Underinflated tires will increase tire rolling
resistance resulting in higher fuel consumption.

CAUTION!
If a transmission fluid leak occurs, visit an
authorized dealer immediately. Severe
transmission damage may occur. An
authorized dealer has the proper tools to
adjust the fluid level accurately.
WARNING!
Improperly inflated tires are dangerous
and can cause collisions.
Underinflation increases tire flexing and
can result in overheating and tire failure.
Overinflation reduces a tire's ability to
cushion shock. Objects on the road and
chuckholes can cause damage that
result in tire failure.

Overinflated or underinflated tires can affect
vehicle handling and can fail suddenly,
resulting in loss of vehicle control.

Unequal tire pressures can cause
steering problems. You could lose
control of your vehicle.
Unequal tire pressures from one side of
the vehicle to the other can cause the
vehicle to drift to the right or left.

Always drive with each tire inflated to the
recommended cold tire inflation pressure.

WARNING! (Continued)
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SERVICING AND MAINTENANCE
234
Tire Pressures For High Speed Operation
The manufacturer advocates driving at safe
speeds and within posted speed limits.
Where speed limits or conditions are such
that the vehicle can be driven at high speeds,
maintaining correct tire inflation pressure is
very important. Increased tire pressure and
reduced vehicle loading may be required for
high-speed vehicle operation. Refer to an
authorized tire dealer or original equipment
vehicle dealer for recommended safe oper-
ating speeds, loading and cold tire inflation
pressures.
Radial Ply Tires
Tire Repair
If your tire becomes damaged, it may be
repaired if it meets the following criteria:
The tire has not been driven on when flat.

The damage is only on the tread section of
your tire (sidewall damage is not repairable).

The puncture is no greater than a ¼ of an
inch (6 mm).
Consult an authorized tire dealer for tire
repairs and additional information.
Damaged Run Flat tires, or Run Flat tires
that have experienced a loss of pressure
should be replaced immediately with another
Run Flat tire of identical size and service
description (Load Index and Speed Symbol).
Replace the tire pressure sensor as well as it
is not designed to be reused.
Run Flat Tires — If Equipped
Run Flat tires allow you the capability to
drive 50 miles (80 km) at 50 mph (80 km/h)
after a rapid loss of inflation pressure. This
rapid loss of inflation is referred to as the
Run Flat mode. A Run Flat mode occurs
when the tire inflation pressure is of/or below
14 psi (96 kPa). Once a Run Flat tire reaches
the run flat mode it has limited driving capa -
bilities and needs to be replaced immedi -
ately. A Run Flat tire is not repairable. When
a run flat tire is changed after driving with
underinflated tire condition, please replace
the TPM sensor as it is not designed to be
reused when driven under run flat mode 14
psi (96 kPa) condition.
NOTE:
TPM Sensor must be replaced after driving
the vehicle on a flat tire condition.
It is not recommended driving a vehicle
loaded at full capacity or to tow a trailer
while a tire is in the run flat mode.
See the tire pressure monitoring section for
more information.
WARNING!
High speed driving with your vehicle under
maximum load is dangerous. The added
strain on your tires could cause them to
fail. You could have a serious collision. Do
not drive a vehicle loaded to the maximum
capacity at continuous speeds above
75 mph (120 km/h).
WARNING!
Combining radial ply tires with other types
of tires on your vehicle will cause your
vehicle to handle poorly. The instability
could cause a collision. Always use radial
ply tires in sets of four. Never combine
them with other types of tires.
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235
Tire Spinning
When stuck in mud, sand, snow, or ice
conditions, do not spin your vehicle's wheels
above 30 mph (48 km/h) or for longer than
30 seconds continuously without stopping.
Refer to “Freeing A Stuck Vehicle” in “In
Case Of Emergency” for further information.
Tread Wear Indicators
Tread wear indicators are in the original
equipment tires to help you in determining
when your tires should be replaced.Tire Tread
These indicators are molded into the bottom
of the tread grooves. They will appear as
bands when the tread depth becomes a 1/16
of an inch (1.6 mm). When the tread is worn
to the tread wear indicators, the tire should
be replaced.
Refer to “Replacement Tires” in this section
for further information.
Life Of Tire
The service life of a tire is dependent upon
varying factors including, but not limited to:
Driving style
Tire pressure - Improper cold tire inflation
pressures can cause uneven wear patterns
to develop across the tire tread. These
abnormal wear patterns will reduce tread
life, resulting in the need for earlier tire
replacement
Distance driven
Performance tires, tires with a speed
rating of V or higher, and Summer tires
typically have a reduced tread life. Rota-
tion of these tires per the vehicle sched -
uled maintenance is highly recommended
WARNING!
Fast spinning tires can be dangerous.
Forces generated by excessive wheel
speeds may cause tire damage or failure. A
tire could explode and injure someone. Do
not spin your vehicle's wheels faster than
30 mph (48 km/h) for more than 30
seconds continuously when you are stuck,
and do not let anyone near a spinning
wheel, no matter what the speed.1 — Worn Tire
2 — New Tire
WARNING!
Tires and the spare tire should be replaced
after six years, regardless of the remaining
tread. Failure to follow this warning can
result in sudden tire failure. You could lose
control and have a collision resulting in
serious injury or death.
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237
Tire Types
All Season Tires — If Equipped
All Season tires provide traction for all
seasons (Spring, Summer, Autumn, and
Winter). Traction levels may vary between
different all season tires. All season tires can
be identified by the M+S, M&S, M/S or MS
designation on the tire sidewall. Use all
season tires only in sets of four; failure to do
so may adversely affect the safety and
handling of your vehicle.

Summer Or Three Season Tires — If Equipped

Summer tires provide traction in both wet
and dry conditions, and are not intended to
be driven in snow or on ice. If your vehicle is
equipped with Summer tires, be aware these
tires are not designed for Winter or cold
driving conditions. Install Winter tires on
your vehicle when ambient temperatures are
less than 40°F (5°C) or if roads are covered
with ice or snow. For more information,
contact an authorized dealer.

Summer tires do not contain the all season desig-
nation or mountain/snowflake symbol on the tire
sidewall. Use Summer tires only in sets of four;
failure to do so may adversely affect the safety
and handling of your vehicle.

Snow Tires
Some areas of the country require the use of
snow tires during the Winter. Snow tires can
be identified by a “mountain/snowflake”
symbol on the tire sidewall.
If you need snow tires, select tires
equivalent in size and type to the
original equipment tires. Use snow
tires only in sets of four; failure to
do so may adversely affect the safety and
handling of your vehicle.
Snow tires generally have lower speed ratings
than what was originally equipped with your
vehicle and should not be operated at
sustained speeds over 75 mph (120 km/h).
For speeds above 75 mph (120 km/h) refer
to original equipment or an authorized tire
dealer for recommended safe operating
speeds, loading and cold tire inflation pres -
sures. While studded tires improve performance on
ice, skid and traction capability on wet or dry
surfaces may be poorer than that of
non-studded tires. Some states prohibit
studded tires; therefore, local laws should be
checked before using these tire types.
Spare Tires — If Equipped
NOTE:
For vehicles equipped with Tire Service Kit
instead of a spare tire, please refer to “Tire
Service Kit” in “In Case Of Emergency” in
the Owner’s Manual for further information.
Refer to the “Towing Requirements - Tires”
in “Starting And Operating” in the Owner’s
Manual for restrictions when towing with a
spare tire designated for temporary emer
-
gency use.
WARNING!
Do not use Summer tires in snow/ice
conditions. You could lose vehicle control,
resulting in severe injury or death. Driving
too fast for conditions also creates the
possibility of loss of vehicle control.
CAUTION!
Because of the reduced ground clearance,
do not take your vehicle through an
automatic car wash with a compact or
limited use temporary spare installed.
Damage to the vehicle may result.
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SERVICING AND MAINTENANCE
242
If you are storing your vehicle for more than
21 days, we recommend that you take the
following steps to minimize the drain on your
vehicle's battery:
Disconnect the negative cable from
battery.
If your vehicle is equipped with Stop/Start
system then disconnect both the main and
supplemental negative battery cables.
Any time you store your vehicle or keep it
out of service (i.e., vacation) for two weeks
or more, run the air conditioning system at
idle for about five minutes in the fresh air
and high blower setting. This will ensure
adequate system lubrication to minimize
the possibility of compressor damage
when the system is started again.
If assistance is needed to disconnect the
battery system, see your authorized dealer.Battery Cable Disconnect
NOTE:
You must isolate the supplemental battery
connection point, as well as the main
battery terminal from the post, as shown in
the image, to fully de-energize both
batteries for storage. If assistance is
needed to disconnect the battery system,
see an authorized dealer.
Do not disconnect the Intelligent Battery
Sensor (IBS), or your Stop/Start system
may not function for up to 24 hours, due
to the IBS being set into learn mode.
BODYWORK
Body And Underbody Maintenance
Cleaning Headlights
Your vehicle is equipped with plastic head -
lights and fog lights that are lighter and less
susceptible to stone breakage than glass
headlights.
Plastic is not as scratch resistant as glass
and therefore different lens cleaning proce -
dures must be followed.
To minimize the possibility of scratching the
lenses and reducing light output, avoid
wiping with a dry cloth. To remove road dirt,
wash with a mild soap solution followed by
rinsing.
Do not use abrasive cleaning components,
solvents, steel wool or other aggressive mate -
rial to clean the lenses.
CAUTION!
If the negative battery cables are not
isolated properly it can cause a potential
power spike or surge in the system,
resulting in damage to essential electrical
components.
1 — Supplemental Negative Battery Cable
2 — Main Negative Battery Cable
3 — Intelligent Battery Sensor (IBS)
4 — Main Negative Battery Terminal
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