2008 JEEP WRANGLER fuel

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
transmission control systems. When these systems are
operating properly, your vehicle will provide excellent
performance and fuel economy, as well as engine emis-
sions well within current government regulations.
If any of these systems require service, the OBD II system
will turn on the “Malfunction Indicator Light.” It will
also store diagnostic codes and other information to
assist your service technician in making repairs. Al-
though your vehicle will usually be drivable and not
need towing, see your authorized dealer for service as
soon as possible.CAUTION!
•Prolonged driving with the “Malfunction Indica-
tor Light” on could cause further damage to the
emission control system. It could also affect fuel
economy and drivability. The vehicle must be
serviced before any emissions tests can be per-
formed.
•If the “Malfunction Indicator Light” is flashing
while the engine is running, severe catalytic con-
verter damage and power loss will soon occur.
Immediate service is required.
MAINTAINING YOUR VEHICLE 379
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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.
380 MAINTAINING YOUR VEHICLE

CAUTION!
Overfilling or underfilling the crankcase will cause
aeration or loss of oil pressure. This could damage
your engine.
Change Engine Oil
Refer to the Maintenance Schedule in Section 8 for
recommended engine oil change intervals.
Engine Oil Selection
For best performance and maximum protection for all
engines under all types of operating conditions, the
manufacturer recommends engine oils that are API Cer-
tified and meet the requirements of DaimlerChrysler
Material Standard MS-6395.
American Petroleum Institute (API) Engine Oil
Identification Symbol
This symbol means that the oil has
been certified by the American
Petroleum Institute (API). The
manufacturer only recommends
API Certified engine oils.
Engine Oil Viscosity (3.8L Engines)
SAE 5W-20 engine oil is recommended for all operating
temperatures. This engine oil improves low temperature
starting and vehicle fuel economy.
The engine oil filler cap also shows the recommended
engine oil viscosity for your engine. For information on
engine oil filler cap location, refer to the “Engine Com-
partment” illustration in this section.
384 MAINTAINING YOUR VEHICLE

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

Following off-road usage, completely inspect the under-
body of your vehicle. Check tires, body structure, steer-
ing, suspension and exhaust system for damage. Check
threaded fasteners for looseness, particularly on the
chassis, drivetrain components, steering and suspension.
Retighten, if required, to torque values specified in the
Service Manual. Also check for accumulations of vegeta-
tion or brush that could become a fire hazard, or conceal
damage to fuel lines, brake hoses, axle pinion seals, and
propeller shafts. Check air conditioning drain tube on the
lower dash wall in the engine compartment for mud or
debris, and clean as required. A plugged tube will
adversely affect air conditioning performance.CAUTION!
Under frequent heavy-duty driving conditions,
change all lubricants, and lubricate body compo-
nents more often than in normal service to prevent
excessive wear.
Appearance Care And Protection From Corrosion
Protection Of Body And Paint From Corrosion
Vehicle body care requirements vary according to geo-
graphic locations and usage. Chemicals that make roads
passable in snow and ice, and those that are sprayed on
trees and road surfaces during other seasons, are highly
corrosive to the metal in your vehicle. Outside parking,
which exposes your vehicle to airborne contaminants,
road surfaces on which the vehicle is operated, extreme
406 MAINTAINING YOUR VEHICLE

Cavity CartridgeFuseMini
Fuse Description
J4 25 Amp Natural Driver Door Node
J5 25 Amp Natural Passenger Door Node
J6 40 Amp Green Anti-Lock Brake System
(ABS) Pump Feed/ESP
J7 30 Amp Pink Anti-Lock Brake System
(ABS) Valve Feed/ESP
J8 — —
J9 40 Amp Green PZEV Sec Motor Feed/
Flex Fuel
J10 30 Amp Pink Headlamp Wash Relay/
Manifold Tuning Valve
J11 30 Amp Pink Sway BarCavity Cartridge
FuseMini
Fuse Description
J13 60 Amp Yellow Ignition Off Draw
(IOD) — Main
J14 40 Amp Green EBL (Rear Window De-
fogger)
J15 30 Amp Pink Rear Blower
J17 40 Amp Green Starter Solenoid
J18 20 Amp Yellow Powertrain Control
Module (PCM) Trans
Range
J19 60 Amp Yellow Radiator Fan
J20 30 Amp Pink Front Wiper LO/HI
414 MAINTAINING YOUR VEHICLE

Cavity CartridgeFuseMini
Fuse Description
M16 10 Amp
Red Occupant Restraint
Controller (ORC)
M17 15 Amp
Blue Left Tail/License/Park
Lamp (LT-TAIL/LIC/
PRK LMP)
M18 15 Amp
Blue Right Tail/Park/Run
Lamp (RT-TAIL/PRK/
RUN LMP)
M19 25 Amp
Natural Auto Shut Down (ASD
#1 and #2)
M20 15 Amp
Blue Cabin Compartment
Node Interior Light
(CCN INT LIGHT),
Switch Bank (SW
BANK)
M21 20 Amp
Yellow Auto Shut Down (ASD
#3)Cavity Cartridge
FuseMini
Fuse Description
M22 10 Amp
Red Right Horn (RT HORN
(HI/LOW)
M23 10 Amp
Red Left Horn (LT HORN
(HI/LOW)
M24 25 Amp
Natural Rear Wiper (REAR
WIPER)
M25 20 Amp
Yellow Fuel Pump (FUEL
PUMP), Diesel Lift
Pump (DSL LIFT
PUMP) — Export Only
M26 — —
M27 10 Amp
Red Ignition Switch Feed,
Wireless Module
M28 10 Amp
Red PCM Feed/TCM
M29 — —
MAINTAINING YOUR VEHICLE 417
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