check engine JEEP WRANGLER UNLIMITED 2008 Owners Manual

•Airbag deployment level (if applicable)
•Impact acceleration and angle
•Seat belt status
•Brake status (service and parking brakes)
•Accelerator status (including vehicle speed)
•Engine control status (including engine speed)
•Transmission gear selection
•Cruise control status
•Traction/stability control status
•Tire pressure monitoring system (TPMS) status
Child Restraint
Everyone in your vehicle needs to be buckled up at all
times — babies and children, too. Every state in the
United States and all Canadian provinces require that
small children ride in proper restraint systems. This is the
law, and you can be prosecuted for ignoring it.
Children 12 years and under should ride properly buck-
led up in a rear seat, if available. According to crash
statistics, children are safer when properly restrained in
the rear seats, rather than in the front.
There are different sizes and types of restraints for
children from newborn size to the child almost large
enough for an adult safety belt. Always check the child
seat owner’s manual to ensure you have the correct seat
for your child. Use the restraint that is correct for your
child.
62 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE

•Do not inhale exhaust gases. They contain carbon
monoxide, a colorless and odorless gas which can kill.
Never run the engine in a closed area, such as a
garage, and never sit in a parked vehicle with the
engine running for an extended period. If the vehicle is
stopped in an open area with the engine running for
more than a short time, adjust the ventilation system
to force fresh, outside air into the vehicle.
•Guard against carbon monoxide with proper mainte-
nance. Have the exhaust system inspected every time
the vehicle is raised. Have any abnormal conditions
repaired promptly. Until repaired, drive with all side
windows fully open.
•Always run the climate control in panel or floor mode
when driving with any windows open, even if only
slightly, to help keep fresh air circulating inside the
vehicle. Otherwise poisonous gases could be drawn
into the vehicle.
•On hardtop models, keep the tailgate window closed
when driving your vehicle. On fabric top models, do
not drive with the rear window curtain up unless the
side curtains are also open. This will prevent carbon
monoxide and other poisonous exhaust gases from
entering the vehicle.
Safety Checks You Should Make Inside The
Vehicle
Seat Belts
Inspect the seat belt system periodically, checking for
cuts, frays and loose parts. Damaged parts must be
replaced immediately. Do not disassemble or modify the
system.
Seat belt assemblies must be replaced after an accident if
they have been damaged (bent retractor, torn webbing,
etc.). If there is any question regarding seat belt or
retractor condition, replace the seat belt.
76 THINGS TO KNOW BEFORE STARTING YOUR VEHICLE

If the rear wiper is operating when the ignition is turned
OFF, the wiper will automatically return to the “Park”
position. When the vehicle is restarted, the wiper will
resume function at whichever position the switch is set
at.
Adding Washer Fluid
The fluid reservoir for the windshield washers and the
rear window washer is shared. It is located in the front of
the engine compartment, and should be checked for fluid
level at regular intervals. Fill the reservoir with wind-
shield washer solvent (not radiator antifreeze) and oper-
ate the system for a few seconds to flush out the residual
water.
Rear Window Defroster — If Equipped
The pushbutton is located on
the bottom right side of the
blower control knob. Press
this button to turn on the rear
window defroster. An amber
light shows that the defroster
is on.

will flash anytime the ESP or TCS is active and helping to
improve vehicle stability. If the ESP/TCS Indicator Light
is on solid, the ESP system has been turned off by the
driver or a temporary condition exists that will not allow
full ESP function.
27. O/D (Overdrive) Off Indicator LightThis light will illuminate when the O/D OFF
button has been selected. The O/D OFF button is
located on the center console.
28. Sway Bar Indicator Light — If Equipped This light will illuminate when the front sway
bar is disconnected.
29. Electronic Stability Program (ESP)/Brake Assist
System (BAS) Warning Light The ESP/BAS Warning Light in the instrument
cluster comes on when the ignition switch is
turned to the ON position. The light should go out with the engine running. If the ESP/BAS Warning
Light comes on continuously with the engine running, a
malfunction has been detected in either the ESP or the
BAS system. If this light stays illuminated, have the ESP
and BAS checked at your authorized dealer as soon as
possible. Refer to “Electronic Brake Control System” in
Section 3 for more information.
30. Electronic Throttle Control (ETC) Warning Light —
If Equipped
This light informs you of a problem with the
Electronic Throttle Control System. If a prob-
lem is detected while the engine is running, the
light will either stay on or flash depending on
the nature of the problem. Cycle the ignition key when
the vehicle is safely and completely stopped and the shift
lever is placed in the PARK position. The light should
turn off. If the light remains on with the engine running,
your vehicle will usually be drivable, however, see your
authorized dealer for service as soon as possible.

If using a manual transmission vehicle for trailer towing,
all starts must be in 1st gear to avoid excessive clutch
slippage.
Towing Tips — Automatic Transmission
The DRIVE range can be selected when towing. How-
ever, if frequent shifting occurs while in this range, the
OVERDRIVE range should be selected.
NOTE:Using “O/D OFF” while operating the vehicle
under heavy operating conditions will improve perfor-
mance and extend transmission life by reducing exces-
sive shifting and heat build up. This action will also
provide better engine braking.
The automatic transmission fluid and filter should be
changed if you REGULARLY tow a trailer for more than
45 minutes of continuous operation. Refer to the “Main-
tenance Schedule” in Section 8 of this manual for trans-
mission fluid change intervals. NOTE:
Check the automatic transmission fluid level
before towing.
Towing Tips — O/D Off
To reduce potential for automatic transmission overheat-
ing, select the “O/D OFF” feature when driving in hilly
areas or shift the transmission to DRIVE position 2 on
more severe grades. Refer to “Transmission Shifting” in
this section.
Towing Tips — Electronic Speed Control (If
Equipped)

Don’t use in hilly terrain or with heavy loads.
When using the speed control, if you experience speed
drops greater than 10 mph (16 km/h), disengage until
you can get back to cruising speed.
Use speed control in flat terrain and with light loads to
maximize fuel efficiency.
358 STARTING AND OPERATING

Loose Fuel Filler Cap Message
After fuel is added, the vehicle diagnostic system can
determine if the fuel filler cap is possibly loose, improp-
erly installed, or damaged. A “gASCAP” message will be
displayed in the odometer. Tighten the gas cap until a
clickingsound is heard. This is an indication that the
gas cap is properly tightened. Press 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 prob-
lem is detected twice in a row, the system will turn on the
“Malfunction Indicator Light.” Resolving the problem
will turn the “Malfunction Indicator Light.” 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.

Drive Belts — Check Condition and Tension
Belt tension is controlled by means of an automatic
tensioner. No belt tension adjustments are required.
However, belt and belt tensioner condition should be
inspected at the specified intervals, and replaced if re-
quired. See your authorized dealer for service
At the mileage indicated in the Maintenance Schedule,
the condition of all the belts and tensioner should be
checked. Refer to Section 8 of this manual. Improper belt
tension can cause belt slippage and failure.
Belts should be inspected for evidence of cuts, cracks,
glazing, or frayed cords and replaced if there is indication
of damage, which could result in belt failure. Low
generator belt tension can cause battery failure.
Also, check belt routing to make sure there is no inter-
ference between the belts and other engine components.
Spark Plugs
Spark plugs must fire properly to assure engine perfor-
mance and emission control. New plugs should be in-
stalled at the mileage specified in the Maintenance Sched-
ule. Refer to Section 8 of this manual. The entire set
should be replaced if there is any malfunction due to a
faulty spark plug. Refer to Fluids, Lubricants, and Genu-
ine Parts in this section for spark plug information.
Catalytic Converter
The catalytic converter requires the use of unleaded fuel
only. Leaded gasoline will destroy the effectiveness of the
converter as an emission control device.
Under normal operating conditions, the catalytic con-
verter will not require maintenance. However, it is im-
portant to keep the engine properly tuned to assure
proper catalyst operation and prevent possible catalyst
damage.
386 MAINTAINING YOUR VEHICLE

To minimize the possibility of catalytic converter dam-
age:
•Do not shut off the engine or interrupt the ignition
when the transmission is in gear and the vehicle is in
motion.
•Do not try to start the engine by pushing or towing the
vehicle.
•Do not idle the engine with any spark plug wires
disconnected or removed, such as when diagnostic
testing.
•Do not idle the engine for prolonged periods during
very rough idle or malfunctioning operating condi-
tions.
•Do not allow vehicle to run out of fuel.NOTE:
Intentional tampering with emissions control
systems can result in civil penalties being assessed
against you.
Crankcase Emission Control System
Proper operation of this system depends on freedom
from sticking or plugging due to deposits. As vehicle
mileage builds up, the PCV valve and passages may
accumulate deposits. If a valve is not working properly,
replace it with a new valve. DO NOT ATTEMPT TO
CLEAN THE OLD PCV VALVE!
Check ventilation hose for indication of damage or
plugging deposits. Replace if necessary.
Fuel Filter
A plugged fuel filter can cause hard starting or limit the
speed at which a vehicle can be driven. Should an
excessive amount of dirt accumulate in the fuel tank,
frequent replacement of the fuel filter which is mounted
in the fuel tank may be necessary.
388 MAINTAINING YOUR VEHICLE

When additional antifreeze/coolant is needed to main-
tain the proper level, it should be added to the coolant
bottle. Do not overfill.
Points To Remember
NOTE:When the vehicle is stopped after a few miles of
operation, you may observe vapor coming from the front
of the engine compartment. This is normally a result of
moisture from rain, snow, or high humidity accumulat-
ing on the radiator and being vaporized when the
thermostat opens, allowing hot antifreeze/coolant to
enter the radiator.
If an examination of your engine compartment shows no
evidence of radiator or hose leaks, the vehicle may be
safely driven. The vapor will soon dissipate.
•Do not overfill the coolant bottle.
•Check antifreeze/coolant freeze point in the radiator
and in the coolant recovery bottle. If antifreeze/ coolant needs to be added, contents of coolant recov-
ery bottle must also be protected against freezing.
•If frequent antifreeze/coolant additions are required,
or if the level in the recovery bottle does not drop
when the engine cools, the cooling system should be
pressure-tested for leaks.
•Maintain antifreeze/coolant concentration at 50%
HOAT antifreeze/coolant (minimum) and distilled
water for proper corrosion protection of your engine
which contains aluminum components.
•Make sure that the radiator and coolant recovery
bottle hoses are not kinked or obstructed.
•Keep the front of the radiator clean. If your vehicle is
equipped with air conditioning, keep the front of the
condenser clean, also.
•Do not change the thermostat for summer or winter
operation. If replacement is ever necessary, install
398 MAINTAINING YOUR VEHICLE

To properly check the automatic transmission fluid level,
the following procedure must be used:
1. Operate the engine at idle speed and normal operating
temperature.
2. The vehicle must be on level ground.
3. Fully apply parking brake.
4. Place the gear selector momentarily in each gear
position ending with the lever in PARK.
5. Remove the dipstick, wipe it clean and reinsert it until
seated.
6. Remove the dipstick again and note the fluid level on
both sides. The fluid level should be between the HOT
(upper) reference holes on the dipstick at normal operat-
ing temperature. Verify that a solid coating of oil is seen
on both sides of the dipstick. If the fluid is low, add as
required into the dipstick tube.Do not overfill.Afteradding any quantity of oil through the dipstick tube, wait
a minimum of two minutes for the oil to fully drain into
the transmission before rechecking the fluid level.
NOTE:
If it is necessary to check the transmission below
the operating temperature, the fluid level should be
between the two cold (lower) holes on the dipstick with
the fluid at approximately 70° F (21° C) (room tempera-
ture). If the fluid level is correctly established at room
temperature, it should be between the HOT (upper)
reference holes when the transmission reaches 180° F (21°
C). Remember it is best to check the level at the normal
operating temperature.
402 MAINTAINING YOUR VEHICLE