2023 JEEP GLADIATOR check engine light

136GETTING TO KNOW YOUR INSTRUMENT PANEL
Electronic Stability Control (ESC) OFF
Warning Light — If Equipped
This warning light indicates the Electronic
Stability Control (ESC) is off.
Each time the ignition is turned to ON/RUN or ACC/
ON/RUN, the ESC system will be on, even if it was
turned off previously.
Loose Fuel Filler Cap Warning Light —
If Equipped
This warning light will illuminate when the
fuel filler cap is loose. Properly close the
filler cap to disengage the light. If the
light does not turn off, please see an
authorized dealer.
Low Fuel Warning Light
When the fuel level reaches
approximately 2.0 gal (7.5 L), this light
will turn on and a chime will sound. The
light will remain on until fuel is added.
Low Washer Fluid Warning Light —
If Equipped
This warning light will illuminate when the
windshield washer fluid is low
Ú page 364.
Engine Check/Malfunction Indicator
Warning Light (MIL)
The Engine Check/Malfunction Indicator
Light (MIL) is a part of an Onboard
Diagnostic System called OBD II that
monitors engine and automatic
transmission control systems. This warning light
will illuminate when the ignition is in the ON/RUN
position before engine start. If the bulb does not
come on when turning the ignition switch from OFF
to ON/RUN, have the condition checked promptly.
Certain conditions, such as a loose or missing gas
cap, poor quality fuel, etc., may illuminate the light
after engine start. The vehicle should be serviced if
the light stays on through several typical driving
styles. In most situations, the vehicle will drive
normally and will not require towing.
When the engine is running, the MIL may flash to
alert serious conditions that could lead to
immediate loss of power or severe catalytic
converter damage. The vehicle should be serviced
by an authorized dealer as soon as possible if this
occurs.
Service 4WD Warning Light — If Equipped
This warning light will illuminate to signal
a fault with the 4WD system. If the light
stays on or comes on during driving, it
means that the 4WD system is not
functioning properly and that service is required. It
is recommend you drive to the nearest service
center and have the vehicle serviced immediately.
WARNING!
A malfunctioning catalytic converter, as
previously referenced, can reach higher
temperatures than in normal operating
conditions. This can cause a fire if you drive
slowly or park over flammable substances such
as dry plants, wood, cardboard, etc. This could
result in death or serious injury to the driver,
occupants or others.
CAUTION!
Prolonged driving with the Malfunction Indicator
Light (MIL) on could cause damage to the
vehicle control system. It also could affect fuel
economy and driveability. If the MIL is flashing,
severe catalytic converter damage and power
loss will soon occur. Immediate service is
required.

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138GETTING TO KNOW YOUR INSTRUMENT PANEL
AdBlue® (UREA) Injection System Failure
Warning Light — If Equipped
This warning light will illuminate along
with a dedicated message on the display
(if equipped) if an unknown fluid not
conforming with acceptable
characteristics is inserted, or if an average
consumption of AdBlue® (UREA) over 50% is
detected. Contact an authorized dealer as soon as
possible. If the problem is not solved, a specific message will
appear on the Instrument Cluster Display
whenever a certain threshold is reached until it will
no longer be possible to start the engine.
When about 125 miles (200 km) are remaining
before the AdBlue® (UREA) tank is empty, a
continuous dedicated message will appear on the
instrument panel, accompanied by a buzzer sound
(if equipped).
YELLOW INDICATOR LIGHTS
4WD Indicator Light — If Equipped
This light alerts the driver that the vehicle
is in the four-wheel drive mode, and the
front and rear driveshafts are
mechanically locked together forcing the
front and rear wheels to rotate at the same speed.
4WD Low Indicator Light — If Equipped
This light alerts the driver that the vehicle
is in the 4WD Low mode. The front and
rear driveshafts are mechanically locked
together forcing the front and rear
wheels to rotate at the same speed. Low range
provides a greater gear reduction ratio to provide
increased torque at the wheels.
4WD Part Time Indicator Light —
If Equipped
This light alerts the driver that the vehicle
is in the four-wheel drive part time mode,
and the front and rear driveshafts are
mechanically locked together forcing the
front and rear wheels to rotate at the same speed.
Axle Locker Fault Indicator Light —
If Equipped
This light indicates when front and/or
rear axle locker fault has been detected.
Rear Axle Lock Indicator Light —
If Equipped
This light indicates when the rear axle
lock has been activated Ú page 161.
Front And Rear Axle Lock Indicator Light —
If Equipped
This light indicates when the front, rear,
or both axles have been locked. The
telltale will display the lock icon on the
front and rear axles to indicate the
current lock status.
CAUTION!
The TPMS has been optimized for the original
equipment tires and wheels. TPMS pressures
and warning have been established for the tire
size equipped on your vehicle. Undesirable
system operation or sensor damage may result
when using replacement equipment that is not
of the same size, type, and/or style. Aftermarket
wheels can cause sensor damage. Using
aftermarket tire sealants may cause the Tire
Pressure Monitoring System (TPMS) sensor to
become inoperable. After using an aftermarket
tire sealant it is recommended that you take
your vehicle to an authorized dealer to have your
sensor function checked.

23_JT_OM_EN_USC_t.book Page 138

142GETTING TO KNOW YOUR INSTRUMENT PANEL
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.
ONBOARD DIAGNOSTIC SYSTEM
(OBD II) C
YBERSECURITY
Your vehicle is required to have an OBD II and a
connection port to allow access to information
related to the performance of your emissions
controls. Authorized service technicians may need
to access this information to assist with the
diagnosis and service of your vehicle and
emissions system Ú page 214.
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 and/or provinces that require
an Inspection and Maintenance (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.
The OBD II system may not be ready if your vehicle
was recently serviced, recently had a depleted
battery or a battery replacement. 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 following:

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.
CAUTION!
Prolonged driving with the MIL on could cause
further damage to the emission control
system. It could also affect fuel economy and
driveability. The vehicle must be serviced
before any emissions tests can be performed.
If the MIL is flashing while the vehicle is
running, severe catalytic converter damage
and power loss will soon occur. Immediate
service is required.
WARNING!
ONLY an authorized service technician should
connect equipment to the OBD II connection
port in order to read the VIN, diagnose, or
service your vehicle.
If unauthorized equipment is connected to the
OBD II connection port, such as a
driver-behavior tracking device, it may:
Be possible that vehicle systems,
including safety related systems, could be
impaired or a loss of vehicle control could
occur that may result in an accident
involving serious injury or death.
Access, or allow others to access, infor -
mation stored in your vehicle systems,
including personal information.

23_JT_OM_EN_USC_t.book Page 142

STARTING AND OPERATING149
(Continued)
3. The system will automatically engage the
starter to crank the engine. If the vehicle fails
to start, the starter will disengage automat-
ically after 25 seconds.
4. If you wish to stop the cranking of the engine prior to the engine starting, push the ENGINE
START/STOP button again.
5. Check that the Oil Pressure Warning Light has turned off.
6. Release the parking brake.
STARTING FLUIDS
The engine is equipped with a glow plug preheating
system. If the instructions in this manual are
followed, the engine should start in all conditions
and no type of starting fluid should be used.
NORMAL OPERATION — DIESEL ENGINE
Observe the following when the diesel engine is
operating:
All message center lights are off.
Malfunction Indicator Light (MIL) is off.
Engine Oil Pressure telltale is not illuminated.
Voltmeter operation.
The voltmeter may show a gauge fluctuation at
various engine temperatures. This is caused by the
glow plug heating system. The number of cycles
and the length of the cycling operation is controlled by the engine control module. Glow plug heater
operation can run for several minutes. Once the
heater operation is complete the voltmeter needle
will stabilize.
COLD WEATHER PRECAUTIONS
Operation in ambient temperature below 32°F
(0°C) may require special considerations. The
following charts suggest these options:
Fuel Operating Range
NOTE:Use Ultra Low Sulfur Diesel (ULSD) Fuels
ONLY.

Fuel Operating Range Chart

*Number 1 ULSD Fuel should only be used where
extended arctic conditions 0°F (-18°C) exist.
WARNING!
Do not leave children or animals inside parked
vehicles in hot weather. Interior heat build-up
may cause serious injury or death.
When leaving the vehicle, always make sure
the keyless ignition node is in the OFF posi -
tion, remove the key fob from the vehicle and
lock the vehicle.
Never leave children alone in a vehicle, or with
access to an unlocked vehicle. Allowing chil -
dren to be in a vehicle unattended is
dangerous for a number of reasons. A child or
others could be seriously or fatally injured.
Children should be warned not to touch the
parking brake, brake pedal or the gear
selector.
Do not leave the key fob in or near the vehicle,
or in a location accessible to children, and do
not leave the ignition of a vehicle equipped
with Keyless Enter ‘n Go™ in the ACC or ON/
RUN position. A child could operate power
windows, other controls, or move the vehicle.
WARNING!
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STARTING AND OPERATING151
NOTE:Under certain conditions the Stop/Start system
may be temporarily disabled and the engine fan
will run after the engine is turned off to protect the
engine. These conditions are under high load and
high temperature conditions.
COOLING SYSTEM TIPS — AUTOMATIC
T
RANSMISSION
To reduce the potential for engine and
transmission overheating in high ambient
temperature conditions, take the following actions:
City Driving — When stopped, shift the transmis -
sion into NEUTRAL (N) and increase engine idle
speed.
Highway Driving — Reduce your speed.
Up Steep Hills — Select a lower transmission
gear.
Air Conditioning — Turn it off temporarily.
NOTE:If the coolant temperature is too high, the A/C will
automatically turn off.
Do Not Operate The Engine With Low Oil
Pressure
If the Low Oil Pressure Warning Light turns on while
driving, stop the vehicle and shut down the engine
as soon as possible. After the vehicle is safely
stopped, restart the engine and monitor the lamp. If the lamp is still illuminated, shut the engine off,
contact an authorized dealer, and do not operate
the vehicle until the cause is corrected. If the lamp
is no longer illuminated, the engine can be
operated, but should be taken to an authorized
dealer as soon as possible for further inspection.
NOTE:Do not operate the vehicle until the cause is
corrected. This light does not show how much oil is
in the engine. The engine oil level must be checked
under the hood.
Do Not Operate The Engine With Failed
Parts
All engine failures give some warning before the
parts fail. Be on the alert for changes in
performance, sounds, and visual evidence that the
engine requires service. Some important clues are:
Engine misfiring or vibrating severely
Sudden loss of power
Unusual engine noises
Fuel, oil or coolant leaks
Sudden change, outside the normal operating
range, in the engine operating temperature
Excessive smoke
Oil pressure drop
ENGINE BREAK-IN RECOMMENDATIONS —
GASOLINE ENGINE (IF EQUIPPED)
A long break-in period is not required for the engine
and drivetrain (transmission and axle) in your
vehicle.
Drive moderately during the first 300 miles
(500 km). After the initial 60 miles (100 km),
speeds up to 50 or 55 mph (80 or 90 km/h) are
desirable.
While cruising, brief full-throttle acceleration within
the limits of local traffic laws contributes to a good
break-in. Wide-open throttle acceleration in low
gear can be detrimental and should be avoided.
The engine oil installed in the engine at the factory
is a high-quality energy conserving type lubricant.
Oil changes should be consistent with anticipated
climate conditions under which vehicle operations
will occur.
For the recommended viscosity and quality grades
see Ú page 424.
CAUTION!
If oil pressure falls to less than normal readings,
shut the engine off immediately. Failure to do so
could result in immediate and severe engine
damage.
4

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152STARTING AND OPERATING
NOTE:A new engine may consume some oil during its first
few thousand miles (kilometers) of operation. This
should be considered a normal part of the break-in
and not interpreted as a problem.
ENGINE BREAK-IN RECOMMENDATIONS —
DIESEL ENGINE (IF EQUIPPED)
The diesel engine does not require a break-in
period due to its construction. Normal operation is
allowed, providing the following recommendations
are followed:
Warm up the engine before placing it under
load.
Do not operate the engine at idle for prolonged
periods.
Use the appropriate transmission gear to
prevent engine lugging.
Observe vehicle oil pressure and temperature
indicators.
Check the coolant and oil levels frequently.
Vary throttle position at highway speeds when
carrying or towing significant weight.
NOTE:Light duty operation such as light trailer towing or
no load operation will extend the time before the
engine is at full efficiency. Reduced fuel economy
and power may be seen at this time.
The engine oil installed in the engine at the factory
is a high-quality energy conserving type lubricant.
Oil changes should be consistent with anticipated
climate conditions under which vehicle operations
will occur. For recommended viscosity and quality
grades Úpage 424. NON-DETERGENT OR
STRAIGHT MINERAL OILS MUST NEVER BE USED.
PARKING BRAKE
Before exiting the vehicle, make sure that the
parking brake is fully applied. Also, be certain to
leave an automatic transmission in PARK, or
manual transmission in REVERSE or FIRST gear.
The parking brake lever is located in the center
console. To apply the parking brake, pull the lever
up as firmly as possible. To release the parking
brake, pull the lever up slightly, push the center
button, then lower the lever completely.
Parking Brake Lever

When the parking brake is applied with the ignition
switch ON, the Brake Warning Light in the
instrument cluster will illuminate.
NOTE:
When the parking brake is applied and the auto -
matic transmission is placed in gear, the Brake
Warning Light will flash. If vehicle speed is
detected, a chime will sound to alert the driver.
Fully release the parking brake before
attempting to move the vehicle.
This light only shows that the parking brake is
applied. It does not show the degree of brake
application.
CAUTION!
Never use Non-Detergent Oil or Straight Mineral
Oil in the engine or damage may result.

23_JT_OM_EN_USC_t.book Page 152

STARTING AND OPERATING171
TO MANUALLY TURN OFF THE STOP/
S
TART SYSTEM

Stop/Start OFF Switch

Push the Stop/Start OFF switch (located on the
switch bank). The light on the switch will illuminate.
The “Stop/Start OFF” message will appear in
instrument cluster display within the Stop/Start
section, and the autostop function will be disabled
Ú page 121.
NOTE: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/
S
TART SYSTEM
Push the Stop/Start Off switch (located on the
switch bank). The light on the switch will turn off.
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 and a
yellow Stop/Start telltale will appear in the
instrument cluster display Ú page 121.
If the “SERVICE STOP/START SYSTEM” message
appears in the instrument cluster display, have the
system checked by an authorized dealer.
STOP/START SYSTEM — MANUAL
TRANSMISSION (IF EQUIPPED)
The Engine Stop/Start (ESS) function is developed
to reduce fuel consumption. The system will stop
the engine automatically during a vehicle stop if
the required conditions are met. Pressing the
clutch pedal will automatically restart the vehicle.
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 electrical system. The
secondary battery is located behind the wheel well
for the front passenger wheel.

Battery Locations

1 — Primary Battery
2 — Secondary Battery
4

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STARTING AND OPERATING173
Battery voltage drops too low
Vehicle is moving faster than 5 mph (8 km/h)
Stop/Start OFF switch is pressed
Transfer case is in 4L or N (Neutral)
Steering wheel is turned beyond threshold (ESS
Models Only)
TO MANUALLY TURN OFF THE STOP/
S
TART SYSTEM

Stop/Start OFF Switch

Push the Stop/Start OFF switch (located on the
switch bank). The light on the switch will illuminate.
The “Stop/Start OFF” message will appear in
instrument cluster display within the Stop/Start
section, and the Autostop function will be disabled
Ú page 121.
NOTE: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/
S
TART SYSTEM
Push the Stop/Start Off switch (located on the
switch bank). The light on the switch will turn off.
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 and a
yellow Stop/Start telltale will appear in the
instrument cluster display Ú page 121.
If the “SERVICE STOP/START SYSTEM” message
appears in the instrument cluster display, have the
system checked by an authorized dealer.
CRUISE CONTROL SYSTEMS — IF EQUIPPED
Your vehicle may be equipped with the Cruise
Control system, or the Adaptive Cruise Control
(ACC) system:
Cruise Control will keep your vehicle at a
constant preset speed.
Adaptive Cruise Control (ACC) will adjust the
vehicle speed up to the preset speed to main -
tain a distance with the vehicle ahead.
NOTE:
In vehicles equipped with ACC, if ACC is not
enabled, Fixed Speed Cruise Control will not
detect vehicles directly ahead of you. Always be
aware of the feature selected.
Only one Cruise Control feature can operate at a
time. For example, if Fixed Speed Cruise Control
is enabled, Adaptive Cruise Control will be
unavailable, and vice versa.
CRUISE CONTROL
When engaged, the Cruise Control system takes
over accelerator operations at speeds greater than
20 mph (32 km/h).
The Cruise Control buttons are located on the right
side of the steering wheel.
4

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