2017 JEEP WRANGLER UNLIMITED service

ONBOARD DIAGNOSTIC SYSTEM — OBD II
Your vehicle is equipped with a sophisticated Onboard
Diagnostic system called OBD II. This system monitors the
performance of the emissions, engine, and automatic trans-
mission control systems. When these systems are operating
properly, your vehicle will provide excellent performance
and fuel economy, as well as engine emissions well within
current government regulations.
If any of these systems require service, the OBD II system
will turn on the Malfunction Indicator Light (MIL). It will
also store diagnostic codes and other information to assist
your service technician in making repairs. Although your
vehicle will usually be drivable and not need towing, see
your authorized dealer for service as soon as possible.

WARNING!(Continued)
vehicle control could occur that may result in an
accident involving serious injury or death.
• Access, or allow others to access, information
stored in your vehicle systems, including personal
information.
For further information, refer to “Cybersecurity” in “Mul-
timedia”.
Loose Fuel Filler Cap Message
After fuel is added, the vehicle diagnostic system can
determine if the fuel filler cap is possibly loose, improperly
installed, or damaged. A “gASCAP” message will be
displayed in the odometer. Tighten the gas cap until a
clicking sound is heard. This is an indication that the gas
cap is properly tightened. Push the odometer reset button
to turn the message off. If the problem persists, the
message will appear the next time the vehicle is started.
This might indicate a damaged cap. If the problem is
detected twice in a row, the system will turn on the MIL.
Resolving the problem will turn the MIL off.
EMISSIONS INSPECTION AND MAINTENANCE
PROGRAMS
In some localities, it may be a legal requirement to pass an
inspection of your vehicle’s emissions control system.
Failure to pass could prevent vehicle registration.
For states that require an Inspection and Mainte-
nance (I/M), this check verifies the “Malfunction
Indicator Light (MIL)” is functioning and is not on
when the engine is running, and that the OBD II system is
ready for testing.
Normally, the OBD II system will be ready. The OBD II
system may notbe ready if your vehicle was recently
serviced, recently had a dead battery or a battery replace-
ment. If the OBD II system should be determined not ready
for the I/M test, your vehicle may fail the test.
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GETTING TO KNOW YOUR INSTRUMENT PANEL 207

WARNING!(Continued)
•The capabilities of an ABS equipped vehicle must
never be exploited in a reckless or dangerous manner
that could jeopardize the user ’s safety or the safety of
others.
ABS is designed to function with the OEM tires. Modifica-
tion may result in degraded ABS performance.
Anti-Lock Brake Warning Light
The yellow “Anti-Lock Brake Warning Light” will turn on
when the ignition is turned to the ON/RUN mode and
may stay on for as long as four seconds.
If the “Anti-Lock Brake Warning Light” remains on or
comes on while driving, it indicates that the anti-lock
portion of the brake system is not functioning and that
service is required. However, the conventional brake sys-
tem will continue to operate normally if the “Brake System
Warning Light” is not on.
If the “Anti-Lock Brake Warning Light” is on, the brake
system should be serviced as soon as possible to restore the
benefits of anti-lock brakes. If the “Anti-Lock Brake Warning
Light” does not come on when the ignition is turned to the
ON/RUN mode, have the light repaired as soon as possible.
Electronic Brake Control System
Your vehicle is equipped with an advanced Electronic
Brake Control system (EBC). This system includes Elec-
tronic Brake Force Distribution (EBD), Brake Assist System
(BAS), Hill Start Assist (HSA), Traction Control System
(TCS), Electronic Stability Control (ESC), and Electronic
Roll Mitigation (ERM). These systems work together to
enhance both vehicle stability and control in various driv-
ing conditions.
Your vehicle may also be equipped with Trailer Sway
Control (TSC) and Hill Descent Control (HDC).
Electronic Brake Force Distribution (EBD)
This function manages the distribution of the braking
torque between the front and rear axles by limiting braking
pressure to the rear axle. This is done to prevent overslip of
the rear wheels to avoid vehicle instability, and to prevent
the rear axle from entering ABS before the front axle.
Brake System Warning Light
The red “Brake System Warning Light” will turn on when
the ignition is turned to the ON/RUN mode and may stay
on for as long as four seconds.
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SAFETY 211

If the “Brake System Warning Light” remains on or comes
on while driving, it indicates that the brake system is not
functioning properly and that immediate service is re-
quired. If the “Brake System Warning Light” does not come
on when the ignition is turned to the ON/RUN mode, have
the light repaired as soon as possible.
Brake Assist System (BAS)
The BAS is designed to optimize the vehicle’s braking
capability during emergency braking maneuvers. The sys-
tem detects an emergency braking situation by sensing the
rate and amount of brake application and then applies
optimum pressure to the brakes. This can help reduce
braking distances. The BAS complements the anti-lock
brake system (ABS). Applying the brakes very quickly
results in the best BAS assistance. To receive the benefit of
the system, you must apply continuous braking pressure
during the stopping sequence, (do not “pump” the brakes).
Do not reduce brake pedal pressure unless braking is no
longer desired. Once the brake pedal is released, the BAS is
deactivated.

The ORC also includes diagnostics that will illuminate the
instrument panel Air Bag Warning Light if a malfunction is
detected that could affect the air bag system. The diagnos-
tics also record the nature of the malfunction. While the air
bag system is designed to be maintenance free, if any of the
following occurs, have an authorized dealer service the air
bag system immediately.
•The Air Bag Warning Light does not come on during the
four to eight seconds when the ignition switch is first in
the ON/RUN position.
• The Air Bag Warning Light remains on after the four to
eight-second interval.
• The Air Bag Warning Light comes on intermittently or
remains on while driving.
NOTE: If the speedometer, tachometer, or any engine
related gauges are not working, the Occupant Restraint
Controller (ORC) may also be disabled. In this condition
the air bags may not be ready to inflate for your protection.
Have an authorized dealer service the air bag system
immediately.

WARNING!(Continued)
•It is dangerous to try to repair any part of the air bag
system yourself. Be sure to tell anyone who works on
your vehicle that it has an air bag system.
• Do not attempt to modify any part of your air bag
system. The air bag may inflate accidentally or may
not function properly if modifications are made.
Take your vehicle to an authorized dealer for any air
bag system service. If your seat, including your trim
cover and cushion, needs to be serviced in any way
(including removal or loosening/tightening of seat
attachment bolts), take the vehicle to your authorized
dealer. Only manufacturer approved seat accessories
may be used. If it is necessary to modify the air bag
system for persons with disabilities, contact your
authorized dealer.
Event Data Recorder (EDR)
This vehicle is equipped with an event data recorder
(EDR). The main purpose of an EDR is to record, in certain
crash or near crash-like situations, such as an air bag
deployment or hitting a road obstacle, data that will assist
in understanding how a vehicle’s systems performed. The
EDR is designed to record data related to vehicle dynamics and safety systems for a short period of time, typically 30
seconds or less. The EDR in this vehicle is designed to
record such data as:
•
How various systems in your vehicle were operating;
• Whether or not the driver and passenger safety belts
were buckled/fastened;
• How far (if at all) the driver was depressing the accel-
erator and/or brake pedal; and,
• How fast the vehicle was traveling.
These data can help provide a better understanding of the
circumstances in which crashes and injuries occur.
NOTE: EDR data are recorded by your vehicle only if a
non-trivial crash situation occurs; no data are recorded by
the EDR under normal driving conditions and no personal
data (e.g., name, gender, age, and crash location) are
recorded. However, other parties, such as law enforcement,
could combine the EDR data with the type of personally
identifying data routinely acquired during a crash investi-
gation.
To read data recorded by an EDR, special equipment is
required, and access to the vehicle or the EDR is needed. In
addition to the vehicle manufacturer, other parties, such as
252 SAFETY

CAUTION!
Prolonged operation of the steering system at the end of
the steering wheel travel will increase the steering fluid
temperature and it should be avoided when possible.
Damage to the power steering pump may occur.
Power Steering Fluid Check
Checking the power steering fluid level at a defined service
interval is not required. The fluid should only be checked
if a leak is suspected, abnormal noises are apparent,
and/or the system is not functioning as anticipated. Coor-
dinate inspection efforts through your authorized dealer.

always a good idea to check for damage. That way you can
get any problems taken care of right away and have your
vehicle ready when you need it.
•Completely inspect the underbody of your vehicle.
Check tires, body structure, steering, suspension, and
exhaust system for damage.
• Inspect the radiator for mud and debris and clean as
required.
• Check threaded fasteners for looseness, particularly on
the chassis, drivetrain components, steering, and sus-
pension. Retighten them, if required, and torque to the
values specified in the Service Manual.
• Check for accumulations of plants or brush. These things
could be a fire hazard. They might hide damage to fuel
lines, brake hoses, axle pinion seals, and propeller shafts.
• After extended operation in mud, sand, water, or similar
dirty conditions, have the radiator, fan, brake rotors,
wheels, brake linings, and axle yokes inspected and
cleaned as soon as possible.