2018 JEEP GRAND CHEROKEE LIMITED service indicator

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 transmission
control systems. When these systems are operating prop-
erly, 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
an 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”.
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 Main-
tenance (I/M), this check verifies the “Malfunc-
tion 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.
Your vehicle has a simple ignition actuated test, which you
can use prior to going to the test station. To check if your
vehicle’s OBD II system is ready, you must do the follow-
ing:
1. Cycle the ignition switch to the ON position, but do not
crank or start the engine.
NOTE: If you crank or start the engine, you will have to
start this test over.
2. As soon as you cycle the ignition switch to the ON position, you will see the “Malfunction Indicator Light
(MIL)” symbol come on as part of a normal bulb check.
3. Approximately 15 seconds later, one of two things will happen:
• The MIL will flash for about ten seconds and then return
to being fully illuminated until you turn OFF the igni-
tion or start the engine. This means that your vehicle’s
OBD II system is not readyand you should notproceed
to the I/M station.
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GETTING TO KNOW YOUR INSTRUMENT PANEL 161

Tread Wear Indicators
Tread wear indicators are in the original equipment tires to
help you in determining when your tires should be re-
placed.
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 isworn 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. Rotation of these tires per the vehicle scheduled
maintenance is highly recommended.