engine JEEP GRAND CHEROKEE 2007 WK / 3.G Service Manual

If the engine shows no sign of starting after two 15
second periods of cranking with the accelerator pedal
held to the floor, the normal starting procedure should be
repeated.
WARNING!
Never pour fuel or other flammable liquids into the
throttle body air inlet opening in an attempt to start
the vehicle. This could result in a flash fire causing
serious personal injury.
Normal Starting — Diesel Engines
1. Turn the ignition key to the ON position.
2. Watch for the “Glow Plug Indicator Light” in the
instrument cluster. Refer to “Instrument Cluster” in
Section 4. It will glow for two to ten seconds or more,depending on engine temperature. When the “Glow Plug
Indicator Light” goes out, the engine is ready to start.
3.Do notpress the accelerator. Turn the ignition key
briefly to START position, and release it. The starter
motor will continue to run, but will automatically disen-
gage itself when the engine is running.
NOTE:The starter motor may run up to 30 seconds in
very cold conditions until the engine is started. The
starter can be disengaged by turning the ignition key to
the OFF position, if required.
4. After the engine starts, allow it to idle for approxi-
mately 30 seconds before driving. This allows oil to
circulate and lubricate the turbocharger.
250 STARTING AND OPERATING

Starting and Operating Cautions — Diesel Engines
WARNING!
NEVER pour fuel or other flammable liquid into the
air inlet opening in an attempt to start the vehicle.
This could result in a flash fire causing serious
personal injury.
•Running a cold engine at high speeds during driving
or idling may damage engine components.
•Before turning off your turbo diesel engine, always
allow the engine to return to normal idle speed andrun for several seconds. This assures proper lubrica-
tion of the turbocharger. This is particularly neces-
sary after any period of hard driving.
Turbocharger “Cool Down”
NOTE:Letting the engine idle after extended operation
allows the turbine housing to cool to normal operating
temperature.
The following chart should be used as a guide in deter-
mining the amount of engine idle time required to
sufficiently cool down the turbocharger before shut
down, depending upon the type of driving and the
amount of cargo.
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5

ENGINE BLOCK HEATER — IF EQUIPPED
The engine block heater warms engine coolant and per-
mits quicker starts in cold weather. Connect the cord to a
standard 110-115 volt AC electrical outlet with grounded,
three wire extension cord.
Use the heater when temperatures below 0°F (-18°C) are
expected to last for several days.
The engine block heater cord is located:
•3.7L/4.7L Engine — coiled and strapped to the engine
oil dipstick tube.
•5.7L Engine — bundled and fastened to the injector
harness.
WARNING!
Remember to disconnect the cord before driving.
Damage to the 110-115 volt AC electrical cord could
cause electrocution.
AUTOMATIC TRANSMISSION
CAUTION!
Damage to the transmission may occur if the follow-
ing precautions are not observed:
•Shift into P (Park) only after the vehicle has come
to a complete stop.
•Shift into or out of R (Reverse) only after the
vehicle has come to a complete stop and the
engine is at idle speed.
•Do not shift from R (Reverse), P (Park), or N
(Neutral) into any forward gear when the engine
is above idle speed.
•Before shifting into any gear, make sure your foot
is firmly on the brake pedal.
STARTING AND OPERATING 253
5

WARNING!
It is dangerous to shift the selector lever out of P
(Park) or N (Neutral) if the engine speed is higher
than idle speed. If your foot is not firmly on the
brake pedal, the vehicle could accelerate quickly
forward or in reverse. You could lose control of the
vehicle and hit someone or something. Only shift
into gear when the engine is idling normally and
when your foot is firmly on the brake pedal.
Brake/Transmission Interlock System
This system prevents you from moving the gear shift out
of P (Park) and into any gear unless the brake pedal is
pressed. This system is active only while the ignition
switch is in the ON position. Always depress thebrake
pedal first,before moving the gear selector out of P
(Park).
5–Speed Automatic Transmission
The electronically controlled transmission provides a
precise shift schedule. The transmission electronics are
self-calibrating; therefore, the first few shifts on a new
vehicle, may be somewhat abrupt. This is a normal
condition, and precision shifts will develop within a few
hundred miles.
254 STARTING AND OPERATING

Gear Ranges
NOTE:After selecting any gear range, wait a moment to
allow the selected gear to engage before accelerating.
This is especially important when the engine is cold. If
there is a need to restart the engine be sure to cycle the
key to the LOCK position before restarting. Transmissiongear engagement may be delayed after restarting the
engine if the key is not cycled to the LOCK position first.
P (Park)
This gear position supplements the parking brake by
locking the transmission. The engine can be started in
this range. Never use P (Park) while the vehicle is in
motion. Apply the parking brake when leaving the
vehicle in this range. Always apply parking brake first,
then place the selector in P (Park) position.
WARNING!
Never use P (Park) position as a substitute for the
parking brake. Always apply parking brake fully
when parked to guard against vehicle movement and
possible injury or damage.Automatic Shift Controls
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5

WARNING!
It is dangerous to shift the selector lever out of P
(Park) or N (Neutral) if the engine speed is higher
than idle speed. If your foot is not firmly on the
brake pedal, the vehicle could accelerate quickly
forward or in reverse. You could lose control of the
vehicle and hit someone or something. Only shift
into gear when the engine is idling normally and
when your right foot is firmly on the brake pedal.
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.
D (Drive)
The transmission automatically upshifts through fifth
gear. The D (Drive) position provides optimum driving
characteristics under all normal operating conditions.
Electronic Range Select (ERS)Operation
The Electronic Range Select (ERS) shift control allows
you to move the shifter left (-) or right (+) when the
shifter is in the D (Drive) position, allowing the selection
256 STARTING AND OPERATING

of the desired top gear. For example, if the driver shifts
the transmission into 3 (third gear), the transmission will
never shift above third gear, but can shift down to 2
(second) or 1 (first), when needed.
On vehicles equipped with 4.7L or 5.7L engines, use of
ERS (or Tow/Haul mode) also enables a additional
underdrive gear which is not normally used during
through-gear accelerations. This additional grade im-
proves vehicle performance and cooling capability when
towing a trailer on certain grades. In ERS mode (on all
transmissions), 1st through 3rd gear are underdrive gears
and 4th gear is direct drive. ERS 5th gear (Overdrive) is
the same as the normal 4th gear.WARNING!
Do not downshift for additional engine braking on a
slippery surface. The drive wheels could lose their
grip and the vehicle could skid.
Screen Display12345*D
Actual Gear(s)
Allowed1 1-2 1-3 1-4 1-5 1-5
* Applies to vehicles equipped with 4.7L/5.7L engines
only.
NOTE:To select the proper gear position for maximum
deceleration (engine braking), move the shift lever to the
left “D(-)” and hold it there. The transmission will shift to
the range from which the vehicle can best be slowed
down.
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5

Overdrive Operation
The automatic transmission includes an electronically
controlled Overdrive (5th gear for 3.7L engine, 4th and
5th gears for 4.7L and 5.7L engines). The transmission
will automatically shift from direct gear to Overdrive if
the following conditions are present:
•the transmission selector is in D (Drive);
•the engine coolant has reached normal operating tem-
perature;
•vehicle speed is above approximately 30 mph (48
km/h);
•the “TOW/HAUL” button has not been activated;
•transmission has reached normal operating tempera-
ture.
NOTE:If the vehicle is started in extremely cold tem-
peratures, the transmission may not shift into Overdriveand will automatically select the most desirable gear for
operation at this temperature. Normal operation will
resume when the transmission fluid temperature has
risen to a suitable level. Refer also to the Note under
torque converter clutch, later in this section.
During cold temperature operation you may notice de-
layed upshifts depending on engine and transmission
temperature. This feature improves the warm up time of
the engine and transmission.
If the transmission temperature gets extremely hot, the
transmission will automatically select the most desirable
gear for operation at this temperature. If the transmission
temperature becomes hot enough, the “TRANSMISSION
OVER TEMP” message may display and the transmis-
sion may downshift out of Overdrive until the transmis-
sion cools down. After cool down, the transmission will
resume normal operation.
258 STARTING AND OPERATING

In high ambient temperatures with sustained high engine
speed and load, an upshift followed shortly thereafter by
a downshift may occur. This is a normal part of the
overheat protection strategy when operating in the
“Tow/Haul” mode.
The transmission will downshift from Overdrive to the
most desirable gear if the accelerator pedal is fully
depressed at vehicle speeds above approximately 35 mph
(56 km/h).
When To Use “TOW/HAUL” Mode — If Equipped
When driving in hilly areas, towing a trailer, carrying a
heavy load, etc., and frequent transmission shifting oc-
curs, press the “TOW/HAUL” button. This will improve
performance and reduce the potential for transmission
overheating or failure due to excessive shifting. When
operating in “TOW/HAUL” mode, the transmission will
shift to direct gear and Overdrive will be enabled under
steady cruise conditions.The “TOW/HAUL” light will illuminate in the instru-
ment cluster to indicate when the switch has been
activated. Pressing the switch a second time restores
normal operation. If the “TOW/HAUL” mode is desired,
the switch must be pressed each time the engine is
started.
Tow/Haul Button
STARTING AND OPERATING 259
5

Transmission Limp Home Mode
Transmission function is monitored for abnormal condi-
tions. If a condition is detected that could result in
transmission damage, the transmission limp home mode
will be engaged. In this mode, the transmission will
remain in the current gear (3.7L engine) or in direct gear
(4.7L and 5.7L engines) until the vehicle is brought to a
stop.
To reset the transmission, use the following procedure:
1. Stop the vehicle.
2. Move the shift lever to the P (Park) position.
3. Turn off the engine, be sure to turn the key to the
LOCK position.
4. Wait approximately 10 seconds, then restart the en-
gine.
5. Move the shift lever to the desired gear range.If the problem is no longer detected, the transmission will
return to normal operation. If the problem persists, P
(Park), R (Reverse), and N (Neutral) will continue to
operate. Only 2nd gear (3.7L engine) or 3rd gear (4.7L
and 5.7L engines) will be available in the D (Drive)
position. Have the transmission checked at your autho-
rized dealer as soon as possible.
Torque Converter Clutch
A feature, designed to improve fuel economy, has been
included in the automatic transmission on your vehicle.
A clutch within the torque converter engages automati-
cally at a calibrated speed at light throttle. It engages at
higher speeds under heavier acceleration. This may re-
sult in a slightly different feeling or response during
normal operation in high gear. When the vehicle speed
drops below a calibrated speed, or during acceleration,
the clutch automatically and smoothly disengages. The
feature is operational in Overdrive and in Drive.
260 STARTING AND OPERATING