engine JEEP WRANGLER 2007 JK / 3.G Service Manual

R (Reverse)
Use this range only after the vehicle has come to a
complete stop.
N (Neutral)
Shift into N (Neutral) when the vehicle is standing for
prolonged periods with the engine running. The engine
may be started in this range. Set the parking brake if you
must leave the vehicle.
NOTE:Towing the vehicle, coasting, or driving for any
other reason with selector lever in N (Neutral) can result
in severe transmission damage. Refer to “Recreational
Towing” in Section 5 and “Towing a Disabled Vehicle” in
Section 6 of this manual.Overdrive (O/D)
For most city and highway driving. The transmission
contains an electronically controlled Overdrive, and will
automatically shift from D (Drive) to O/D (Overdrive) if
the following conditions are present:
•The transmission selector is in D (Drive).
•The O/D OFF switch has not been activated.
•Vehicle speed is above approximately 30 mph (48
km/h).
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When frequent transmission shifting occurs while using
Overdrive, such as when operating the vehicle under
heavy load conditions (for example, in hilly terrain,
strong head winds, or trailer towing), turning off over-
drive will improve performance and extend transmission
life by reducing excessive shifting and heat buildup.Overdrive can be locked out by pressing the O/D OFF
switch located on the center console. The O/D OFF
indicator light (on the switch) will illuminate to show
that the switch has been activated. When the indicator
light is on, Overdrive is locked out. Pressing the switch a
second time restores the Overdrive function. The lockout
feature is useful when towing a trailer or carrying a
heavy load.
2 (Second)
For moderate grades and to assist braking on dry pave-
ment or in mud and snow. Begins at a stop in low gear
with automatic upshift to 2nd gear. Will not shift to 3rd.
1 (First)
For hard pulling at low speeds in mud, sand, snow, or on
steep grades. Begins and stays in low gear with no
upshift. Provides engine compression braking at low
speeds.
Overdrive Off Switch
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WARNING!
Never use P (Park) position with an automatic trans-
mission as a substitute for the parking brake. Always
apply parking brake fully when parked to guard
against vehicle movement and possible injury or
damage.
CAUTION!
•Before moving the shift lever out of P (Park), you
must turn the ignition from LOCK so the steering
wheel and shift lever are released. Otherwise,
damage to steering column or shifter could result.
•Never race the engine with the brakes on and the
vehicle in gear, and never hold the vehicle on an
incline without applying the brakes. These prac-
tices can overheat and damage the transmission.
•When “rocking” a stuck vehicle by moving be-
tween D (Drive) and R (Reverse), do not spin the
wheels faster than 15 mph (24 km/h), or drivetrain
damage may result.
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This transfer case is intended to be driven in the two
wheel drive (2H) position for normal street and highway
conditions such as hard surfaced roads.
In the events when additional traction is required, the
transfer case 4H and 4L positions can be used to lock the
front and rear driveshafts together and force the front
and rear wheels to rotate at the same speed. This is
accomplished by simply moving the shift lever to these
positions. The 4H and 4L positions are intended for loose,
slippery road surfaces only and not intended for normal
driving. Driving in the 4H and 4L positions on hard
surfaced roads will cause increased tire wear and damage
to the driveline components.
The “4WD Indicator Light” (located in the instrument
cluster) alerts the driver that the vehicle is in four wheel
drive and that the front and rear driveshafts are locked
together. This light illuminates when the transfer case is
shifted into the 4H position.NOTE:Do not attempt to make a shift while only the
front or rear wheels are spinning. The transfer case is not
equipped with a synchronizer and therefore the front and
rear driveshafts speeds must be equal for the shift to take
place. Shifting while only the front or rear wheels are
spinning can cause damage to the transfer case.
When operating your vehicle in 4L, the engine speed is
approximately three times (four times for Rubicon mod-
els) that of the 2H or 4H positions at a given road speed.
Take care not to overspeed the engine.
Proper operation of four wheel drive vehicles depends on
tires of equal size, type, and circumference on each
wheel. Any difference will adversely affect shifting and
cause damage to the transfer case.
Because four wheel drive provides improved traction,
there is a tendency to exceed safe turning and stopping
speeds. Do not go faster than road conditions permit.
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NOTE:Pausing in transfer case N (Neutral) in vehicles
equipped with an automatic transmission may require
shutting the engine OFF to avoid gear clash while
completing the shift. If difficulty occurs, shift the auto-
matic transmission to N (Neutral), hold foot on brake,
and turn the engine OFF. Make shift to desired mode.
NOTE:Shifting into or out of 4L is possible with the
vehicle completely stopped, however, difficulty may oc-
cur due to the mating teeth not being properly aligned.
Several attempts may be required for clutch teeth align-
ment and shift completion to occur. The preferred
method is with the vehicle rolling at 2 to 3 mph (3 to 5
km/h). Avoid attempting to engage or disengage 4L with
the vehicle moving faster than 2 to 3 mph (3 to 5 km/h).WARNING!
Failure to engage a position completely can cause
transfer case damage or loss of power and vehicle
control. You could have an injury accident. Do not
drive the vehicle unless the transfer case is fully
engaged.
TRAC-LOK™ REAR AXLE — IF EQUIPPED
The Trac-Lok™ rear axle provides a constant driving
force to both rear wheels and reduces wheel spin caused
by the loss of traction at one driving wheel. If traction
differs between the two rear wheels, the differential
automatically proportions the usable torque by providing
more torque to the wheel that has traction.
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Trac-Lok™ is especially helpful during slippery driving
conditions. With both rear wheels on a slippery surface, a
slight application of the accelerator will supply maxi-
mum traction.
WARNING!
On vehicles equipped with a limited-slip differen-
tial, never run the engine with one rear wheel off the
ground. The vehicle may drive through the rear
wheel remaining on the ground and cause you to lose
control of your vehicle.
AXLE LOCK (TRU–LOK™) — RUBICON MODELS
The axle lock switch is located on the lower switch bank
(below the climate controls).
Axle Lock Switch
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Standing Water
Avoid driving in standing water deeper than 20 inches,
and reduce speed appropriately to minimize wave ef-
fects. Maximum speed in 20 inches of water is less than 5
mph (8 km/h).
Maintenance
After driving through deep water, inspect your vehicle
fluids and lubricants (engine oil, transmission oil, axle,
transfer case) to assure the fluids have not been contami-
nated. Contaminated fluid (milky, foamy in appearance)
should be flushed/changed as soon as possible to pre-
vent component damage.
Driving In Snow, Mud and Sand
In heavy snow, when pulling a load, or for additional
control at slower speeds, shift the transmission to a low
gear and shift the transfer case to 4L (Low) if necessary.
Refer to “Four-Wheel Drive Operation” in this section.Do not shift to a lower gear than necessary to maintain
headway. Over-revving the engine can spin the wheels
and traction will be lost.
Avoid abrupt downshifts on icy or slippery roads, be-
cause engine braking may cause skidding and loss of
control.
Hill Climbing
NOTE:Before attempting to climb a hill, determine the
conditions at the crest and/or on the other side.
Before climbing a steep hill,shift the transmission to a
lower gear and shift the transfer case to 4L (Low). Use
first gear and 4L (Low) for very steep hills.
If you stall or begin to lose headwaywhile climbing a
steep hill, allow your vehicle to come to a stop and
immediately apply the brakes. Restart the engine and
shift to R (Reverse). Back slowly down the hill allowing
the compression braking of the engine to help regulate
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your speed. If the brakes are required to control vehicle
speed, apply them lightly and avoid locking or skidding
the tires.
WARNING!
If the engine stalls or you lose headway or cannot
make it to the top of a steep hill or grade, never
attempt to turn around. To do so may result in
tipping and rolling the vehicle. Always back care-
fully straight down a hill in R (Reverse) gear. Never
back down a hill in N (Neutral) using only the brake.
Remember, never drive diagonally across a hill-always
drive straight up or down.
If the wheels start to slip as you approach the crest of a
hill, ease off the accelerator and maintain headway byturning the front wheels slowly left and right. This may
provide a fresh “bite” into the surface and will usually
provide traction to complete the climb.
Traction Downhill
Shift the transmission into a low gear and the transfer
case to 4L (Low) range. Let the vehicle go slowly down
the hill with all four wheels turning against engine
compression drag. This will permit you to control the
vehicle speed and direction.
When descending mountains or hills, repeated braking
can cause brake fade with loss of braking control. Avoid
repeated heavy braking by downshifting the transmis-
sion whenever possible.
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Under-inflation also reduces fuel efficiency and tire
tread life, and may affect the vehicle’s handling and
stopping ability.
•The TPMS is not a substitute for proper tire mainte-
nance, and it is the driver ’s responsibility to maintain
correct tire pressure, even if under-inflation has not
reached the level to trigger illumination of the “Tire
Pressure Monitoring Telltale Light.”
General Information
This device complies with part 15 of the FCC rules and
RSS 210 of Industry Canada. Operation is subject to the
following conditions:
•This device may not cause harmful interference.
•This device must accept any interference received,
including interference that may cause undesired op-
eration.The tire pressure sensors are covered under one of the
following licenses:
United States.....................KR5S120123
Canada........................2671-S120123
FUEL REQUIREMENTS
Your engine is designed to meet all emis-
sions regulations and provide excellent
fuel economy and performance when us-
ing high quality unleaded gasoline having
an octane rating of 87. The use of premium
gasoline is not recommended. The use of
premium gasoline will provide no benefit over high
quality regular gasoline, and in some circumstances may
result in poorer performance.
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Light spark knock at low engine speeds is not harmful to
your engine. However, continued heavy spark knock at
high speeds can cause damage and immediate service is
required.
Poor quality gasoline can cause problems such as hard
starting, stalling and hesitations. If you experience these
symptoms, try another brand of gasoline before consid-
ering service for the vehicle.
Over 40 auto manufacturer’s world wide have issued and
endorsed consistent gasoline specifications (the World-
wide Fuel Charter, WWFC) to define fuel properties
necessary to deliver enhanced emissions, performance,
and durability for your vehicle. The manufacturer recom-
mends the use of gasoline that meets the WWFC speci-
fications if they are available.Reformulated Gasoline
Many areas of the country require the use of cleaner
burning gasoline referred to as “Reformulated Gasoline.”
Reformulated gasolines contains oxygenates, and are
specifically blended to reduce vehicle emissions and
improve air quality.
The manufacturer strongly supports the use of reformu-
lated gasolines. Properly blended reformulated gasolines
will provide excellent performance and durability for the
engine and fuel system components.
Gasoline/Oxygenate Blends
Some fuel suppliers blend unleaded gasoline with oxy-
genates such as 10% ethanol, MTBE, and ETBE. Oxygen-
ates are required in some areas of the country during the
winter months to reduce carbon monoxide emissions.
Fuels blended with these oxygenates may be used in
your vehicle.
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