engine JEEP WRANGLER 2008 JK / 3.G Repair Manual

WARNING!
Improper towing can lead to an injury accident.
Follow these guidelines to make your trailer towing
as safe as possible:
Make certain that the load is secured in the trailer
and will not shift during travel. When trailering
cargo that is not fully secured, dynamic load shifts
can occur that may be difficult for the driver to
control. You could lose control of your vehicle and
have an accident.
•When hauling cargo or towing a trailer, do not over-
load your vehicle or trailer. Overloading can cause a
loss of control, poor performance or damage to brakes,
axle, engine, transmission, steering, suspension, chas-
sis structure or tires.
•Safety chains must always be used between your
vehicle and trailer. Always connect the chains to the
frame or hook retainers of the vehicle hitch. Cross the
chains under the trailer tongue and allow enough
slack for turning corners.
•Vehicles with trailers should not be parked on a grade.
When parking, apply the parking brake on the tow
vehicle. Put the tow vehicle automatic transmission in
PARK. With a manual transmission, shift the transmis-
sion into 1st gear. And with four-wheel-drive vehicles,
make sure the transfer case is not in N (Neutral).
Always, block orchockthe trailer wheels.
•GCWR must not be exceeded.
•Total weight must be distributed between the tow
vehicle and the trailer such that the following four
ratings are not exceeded:
1. GVWR
354 STARTING AND OPERATING

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

Towing Tips — Cooling System
To reduce potential for engine and transmission over-
heating, take the following actions:
Highway Driving
Reduce speed.
Air Conditioning
Turn off temporarily.
refer to Cooling System Operating information in the
Maintenance section of this manual for more informa-
tion.
RECREATIONAL TOWING (BEHIND
MOTORHOME, ETC.)
CAUTION!
Front or rear wheel lifts should not be used. Internal
damage to the transmission or transfer case will occur
if a front or rear wheel lift is used when recreational
towing.
Towing – 2WD Models
Recreational towing is allowed ONLY if the rear drive-
shaft is removed. See your authorized dealer or refer to
the Service Manual. Towing with the rear wheels on the
ground while the driveshaft is connected can result in
severe transmission damage.
STARTING AND OPERATING 359
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Towing – 4WD Models
NOTE:The transfer case must be shifted into N (Neu-
tral) for recreational towing.
Shifting Into Neutral (N)
Use the following procedure to prepare your vehicle for
recreational towing.
CAUTION!
It is necessary to follow these steps to be certain that
the transfer case is fully in N (Neutral) before recre-
ational towing to prevent damage to internal parts.
1. Depress brake pedal.
2. Shift automatic transmission into NEUTRAL or de-
press clutch pedal on manual transmission.
3. Shift transfer case lever into N (Neutral). 4. Start engine.
5. Shift automatic transmission into DRIVE or manual
transmission into gear.
6. Release brake pedal and ensure that there is no vehicle
movement.
7. Shut the engine off and place the ignition key into the
ACC position.
8. Shift automatic transmission into PARK.
9. Apply parking brake.
10. Attach vehicle to the tow vehicle with tow bar.
11. Release parking brake.
12. Disconnect the negative battery cable, and secure it
away from the negative battery post.
360 STARTING AND OPERATING

CAUTION!
Damage to the transmission may occur if the trans-
mission is shifted into PARK with the transfer case in
N (Neutral) and the engine running. With the trans-
fer case in N (Neutral) ensure that the engine is off
prior to shifting the transmission into PARK (refer to
steps7–8above).
Shifting Out Of Neutral (N)
Use the following procedure to prepare your vehicle for
normal usage.
1. Shift automatic transmission into NEUTRAL or de-
press clutch pedal on manual transmission.
2. Shift transfer case lever into desired position.
3. Shift automatic transmission into DRIVE or release
clutch on manual transmissions.NOTE:
When shifting out of transfer case N (Neutral)
on automatic transmission-equipped vehicles, turning
the engine off may be required to avoid gear clash.
WARNING!
You or others could be injured if you leave the
vehicle unattended with the transfer case in the N
(Neutral) position without first fully engaging the
parking brake. The transfer case N (Neutral) position
disengages both the front and rear driveshafts from
the powertrain and will allow the vehicle to move
despite the transmission position. The parking brake
should always be applied when the driver is not in
the vehicle.
STARTING AND OPERATING 361
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WHAT TO DO IN EMERGENCIES
CONTENTS
Hazard Warning Flashers .................364
 If Your Engine Overheats .................365
 Jacking And Tire Changing ................366
▫ Jack Location ........................366
▫ Spare Tire Stowage ....................367 ▫
Preparations For Jacking ................367
▫ Jacking Instructions ....................368
 Jump Starting .........................371
 Emergency Tow Hooks — If Equipped ........374
 Towing A Disabled Vehicle ................374
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IF YOUR ENGINE OVERHEATS
In any of the following situations, you can reduce the
potential for overheating by taking the appropriate ac-
tion.
•On the highways — Slow down.
•In city traffic — While stopped, shift transmission into
NEUTRAL, but do not increase engine idle speed.
NOTE: There are steps that you can take to slow down
an impending overheat condition. If your air conditioner
is on, turn it off. The air conditioning system adds heat to
the engine cooling system and turning off the A/C
removes this heat. You can also turn the Temperature
Control to maximum heat, the Mode Control to floor, and
the Fan Control to High. This allows the heater core to act
as a supplement to the radiator and aids in removing heat
from the engine cooling system.
CAUTION!
Driving with a hot cooling system could damage
your vehicle. If the temperature gauge reads HOT
(H), pull over and stop the vehicle. Idle the vehicle
with the air conditioner turned off until the pointer
drops back into the normal range. If the pointer
remains on HOT (H), and you hear continuous
chimes, turn the engine off immediately, and call for
service.
WHAT TO DO IN EMERGENCIES 365
6

Jacking InstructionsWARNING!
Carefully follow these tire changing warnings to help
prevent personal injury or damage to your vehicle:
•Always park on a firm, level surface as far from the edge
of the roadway as possible before raising the vehicle.
• Block the wheel diagonally opposite the wheel to be
raised.
• Set the parking brake firmly, and shift a automatic
transmission into PARK; or a manual transmission into
REVERSE.
• Never start or run the engine with the vehicle on a jack.
• Do not let anyone sit in the vehicle when it is on a jack.
• Do not get under the vehicle when it is on a jack.
• Only use the jack in the positions indicated and for
lifting this vehicle during a tire change.
• If working on or near a roadway, be extremely careful of
motor traffic.
• To assure that spare tires, flat or inflated are securely
stowed, spares must be stowed with the valve stem
facing the ground.
• Turn on the hazard warning flasher.
Jack Warning Label
368 WHAT TO DO IN EMERGENCIES

2. Park the booster vehicle within cable reach but with-
out letting the vehicles touch. Set the parking brake on
both vehicles, shift the automatic transmission into
PARK, or the manual transmission into NEUTRAL, and
turn the ignition OFF.
3. Turn off the heater, radio, and all unnecessary electri-
cal loads.
4. Connect one end of a jumper cable to the positive
terminal of the booster battery. Connect the other end of
the same cable to the positive terminal of the discharged
battery.
WARNING!
Do not permit vehicles to touch each other as this
could establish a ground connection and personal
injury could result.5. Connect the other cable, first to the negative terminal
of the booster battery and then to the engine of the
vehicle with the discharged battery. Make sure you have
a good contact on the engine.
6. Start the engine in the vehicle which has the booster
battery, let the engine idle a few minutes, then start the
engine in the vehicle with the discharged battery.
7. When removing the jumper cables, reverse the above
sequence exactly. Be careful of the moving belts and fan.
372 WHAT TO DO IN EMERGENCIES

MAINTAINING YOUR VEHICLE
CONTENTS
Engine Compartment – 3.8L ...............378
 Onboard Diagnostic System — OBD II ........379
▫ Loose Fuel Filler Cap Message ............380
 Emissions Inspection And Maintenance
Programs ............................380
 Replacement Parts ......................382
 Authorized Dealer Service ................382
 Maintenance Procedures ..................383
▫ Engine Oil ..........................383 ▫
Drive Belts — Check Condition And Tension . . 386
▫ Spark Plugs .........................386
▫ Catalytic Converter ....................386
▫ Crankcase Emission Control System ........388
▫ Fuel Filter ..........................388
▫ Engine Air Cleaner Filter ................389
▫ Maintenance-Free Battery ................389
▫ Air Conditioner Maintenance .............390
▫ Power Steering Fluid Check ..............391
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