Engine 3.7L JEEP LIBERTY 2002 KJ / 1.G Owner's Guide

INSTALLATION
Gasoline Powered Engines
(1) 2.4L Engine: Position generator to engine and
install 2 mounting bolts. Refer to torque specifica-
tions.
(2) 3.7L Engine: Position generator to engine and
install 3 mounting bolts. Tighten 2 horizontal mount-
ing bolts to specified torque. Tighten 1 verticle
mounting bolt to specified torque. Refer to torque
specifications.
(3) Snap field wire connector into rear of genera-
tor.
(4) Install B+ terminal and nut to generator
mounting stud. Refer to torque specifications.
(5) Snap plastic protective cover to B+ terminal.
CAUTION: Never force a belt over a pulley rim
using a screwdriver. The synthetic fiber of the belt
can be damaged.
CAUTION: When installing a serpentine accessory
drive belt, the belt MUST be routed correctly. The
water pump will be rotating in the wrong direction if
the belt is installed incorrectly, causing the engine
to overheat. Refer to belt routing label in engine
compartment, or refer to Belt Schematics in 7, Cool-
ing System.
(6) Install drive belt Refer to 7, Cooling System for
belt routing, belt adjustment and bolt tightening pro-
cedures.
(7) Install negative battery cable to battery.
GENERATOR DECOUPLER
PULLEY
DESCRIPTION
The generator decoupler is used only with
certain engines.The decoupler is used in place of
the standard generator drive pulley (Fig. 5).
Fig. 3 GENERATOR - 2.4L
1 - UPPER MOUNTING BOLT
2 - GENERTOR
3 - LOWER MOUNTING BOLT
Fig. 4 GENERATOR - 3.7L
1 - GENERATOR
2 - VERTICAL MOUNTING BOLT
3 - HORIZONTAL MOUNTING BOLTS
8F - 26 CHARGING SYSTEMKJ
GENERATOR (Continued)

STARTER MOTOR - GAS POWERED
Starter Motor and Solenoid
Manufacturer Mitsubishi
Engine Application 2.4L / 3.7L
Power Rating 1.4 Kilowatt (1.9 Horsepower)
Voltage12 Volts
** Number of Permanent Magnets 6
Number of Brushes 4
Drive Type Planetary Gear Reduction
Free Running Test Voltage 11.2 Volts
Free Running Test Maximum Amperage Draw 90 Amperes
Free Running Test Minimum Speed 2400 rpm
Solenoid Closing Maximum Voltage Required 7.8 Volts
* Cranking Amperage Draw Test 160 Amperes
*Test at operating temperature. Cold engine, tight (new) engine, or heavy oil will increase starter amperage draw.
**The starter is equipped with permanent magnets. Never strike the starter case to attempt to loosen a sticking/
stuck armature as permanent magnets may crack or break.
STARTER MOTOR
DIAGNOSIS AND TESTING - STARTER MOTOR
Correct starter motor operation can be confirmed
by performing the following free running bench test.
This test can only be performed with starter motor
removed from vehicle. Refer to Specifications for
starter motor specifications.
(1) Remove starter motor from vehicle. Refer to
Starter Motor Removal and Installation.
(2) Mount starter motor securely in a soft-jawed
bench vise. The vise jaws should be clamped on the
mounting flange of starter motor. Never clamp on
starter motor by field frame.
(3) Connect a suitable volt-ampere tester and a
12-volt battery to starter motor in series, and set
ammeter to 100 ampere scale. See instructions pro-
vided by manufacturer of volt-ampere tester being
used.
(4) Install jumper wire from solenoid terminal to
solenoid battery terminal. The starter motor should
operate. If starter motor fails to operate, replace
faulty starter motor assembly.
(5) Adjust carbon pile load of tester to obtain free
running test voltage. Refer to Specifications for
starter motor free running test voltage specifications.
(6) Note reading on ammeter and compare reading
to free running test maximum amperage draw. Refer
to Specifications for starter motor free running test
maximum amperage draw specifications.(7) If ammeter reading exceeds maximum amper-
age draw specification, replace faulty starter motor
assembly.
STARTER SOLENOID
This test can only be performed with starter motor
removed from vehicle.
(1) Remove starter motor from vehicle. Refer to
Starter Motor Removal and Installation.
(2) Disconnect wire from solenoid field coil termi-
nal.
(3) Check for continuity between solenoid terminal
and solenoid field coil terminal with a continuity
tester (Fig. 7). There should be continuity. If OK, go
to Step 4. If not OK, replace faulty starter motor
assembly.
(4) Check for continuity between solenoid terminal
and solenoid case (Fig. 8). There should be continuity.
If not OK, replace faulty starter motor assembly.
REMOVAL
2.4L 4±Cylinder
(1) Disconnect and isolate negative battery cable.
(2) Raise and support vehicle.
(3) Remove solenoid wire from solenoid terminal
(Fig. 11).
(4) Remove battery cable from stud on starter sole-
noid (Fig. 11).
(5) Remove 2 starter mounting bolts (Fig. 9) and
remove starter from vehicle.
KJSTARTING SYSTEM 8F - 39
STARTING SYSTEM (Continued)

INSTALLATION
2.4L 4±Cylinder
(1) Position starter into bellhousing and install 2
bolts. Refer to torque specifications.
(2) Install battery cable and nut to stud on starter
solenoid. Refer to torque specifications.
(3) Install solenoid wire connector to solenoid ter-
minal.
(4) Lower vehicle.
(5) Connect negative battery cable.
3.7L V-6
(1) Position front of starter towards rear of vehicle
with solenoid position rotated until it is located below
starter. Install starter by passing it between exhaust
pipe and transmission bellhousing.
(2) Position starter into bellhousing and install 2
bolts. Refer to torque specifications.
(3) Install battery cable and nut to stud on starter
solenoid. Refer to torque specifications.
(4) Install solenoid wire connector to solenoid ter-
minal.
(5) Position starter heat shield and install nut at
front of starter.
(6) Install 2 starter heat shield bolts at side of
starter.
(7) Install front propeller shaft.
(8) Install 2 flange bolts securing left exhaust
downpipe to crossover pipe.
(9) Lower vehicle.
(10) Connect negative battery cable.
STARTER MOTOR RELAY
DESCRIPTION
The starter relay is an electromechanical device
that switches battery current to the pull-in coil of the
starter solenoid when ignition switch is turned to
Start position. The starter relay is located in the
Power Distribution Center (PDC) in the engine com-
partment. See PDC cover for relay identification and
location.
The starter relay is a International Standards
Organization (ISO) relay. Relays conforming to ISO
specifications have common physical dimensions, cur-
rent capacities, terminal patterns, and terminal func-
tions.
The starter relay cannot be repaired or adjusted
and, if faulty or damaged, it must be replaced.
Fig. 11 STARTER ELECTRICAL CONNECTORS -
2.4L/3.7L
1 - BATERY CABLE NUT
2 - BATTERY CABLE
3 - SOLENOID CONNECTOR
4 - HEAT SHIELD
Fig. 12 STARTER - 3.7L
1-STARTER
2 - MOUNTING BOLTS (2)
KJSTARTING SYSTEM 8F - 41
STARTER MOTOR (Continued)

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
DESCRIPTION..........................1
OPERATION............................1
SPECIFICATIONS
SPECIFICATIONS - IGNITION TIMING.......2
ENGINE FIRING ORDER - 2.4L 4-CYLINDER . 2
ENGINE FIRING ORDER - 3.7L V-6.........2
IGNITION COIL RESISTANCE - 2.4L........2
IGNITION COIL RESISTANCE - 3.7L V-6.....3
SPARK PLUGS........................3
SPARK PLUG CABLE RESISTANCE - 2.4L . . . 3
TORQUE - IGNITION SYSTEM............3
AUTO SHUT DOWN RELAY
DESCRIPTION - PCM OUTPUT.............4
OPERATION
OPERATION - ASD SENSE - PCM INPUT....4
OPERATION - PCM OUTPUT.............4
DIAGNOSIS AND TESTING - ASD AND FUEL
PUMP RELAYS........................4
REMOVAL.............................5
INSTALLATION..........................5
CAMSHAFT POSITION SENSOR
DESCRIPTION
DESCRIPTION - 2.4L....................5
DESCRIPTION-3.7L.....................6
OPERATION
OPERATION - 2.4L.....................6OPERATION - 3.7L.....................6
REMOVAL.............................7
INSTALLATION..........................8
IGNITION COIL
DESCRIPTION..........................9
OPERATION............................9
REMOVAL.............................10
INSTALLATION.........................10
KNOCK SENSOR
DESCRIPTION.........................11
OPERATION...........................11
REMOVAL.............................12
INSTALLATION.........................12
SPARK PLUG
DESCRIPTION.........................12
OPERATION...........................12
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS.........................13
REMOVAL.............................15
CLEANING SPARK PLUGS................15
INSTALLATION.........................15
IGNITION COIL CAPACITOR
DESCRIPTION.........................16
OPERATION...........................16
REMOVAL.............................16
INSTALLATION.........................16
IGNITION CONTROL
DESCRIPTION
The ignition system consists of:
²Spark Plugs
²Ignition Coil(s)
²Powertrain Control Module (PCM)
²Crankshaft Position Sensor
²2 Knock Sensors (3.7L only)
²Camshaft Position Sensor
²The MAP, TPS, IAC and ECT also have an effect
on the control of the ignition system.
OPERATION
2.4L
A common ignition coil divided into 2 halves is
used. Secondary, high-tension spark plug cables are
also used. One half of the coil fires two spark plugs
simultaneously (one plug is the cylinder under com-pression, and the other plug is the cylinder on the
exhaust stroke). Coil half number one fires cylinders
1 and 4. Coil half number two fires cylinders 2 and 3.
The PCM determines which of the coils to charge and
fire at the correct time.
The Auto Shutdown (ASD) relay provides battery
voltage to the ignition coil. The PCM provides a
ground contact (circuit) for energizing the coil. When
the PCM breaks the contact, the energy in the coil
primary transfers to the secondary causing a spark.
The PCM will de-energize the ASD relay if it does
not receive inputs from either the crankshaft or cam-
shaft position sensors.
A distributor is not used with the 2.4L engine.
3.7L
The 3.7L V6 engine uses a separate ignition coil for
each cylinder. The one-piece coil bolts directly to the
cylinder head. Rubber boots seal the secondary ter-
minal ends of the coils to the top of all 6 spark plugs.
A separate electrical connector is used for each coil.
KJIGNITION CONTROL 8I - 1

Because of coil design, spark plug cables (second-
ary cables) are not used. A distributor is not used
with the 3.7L engine.
Two knock sensors (one for each cylinder bank) are
used to help control spark knock.
The Auto Shutdown (ASD) relay provides battery
voltage to each ignition coil. The Powertrain Control
Module (PCM) provides a ground contact (circuit) for
energizing each coil. When the PCM breaks the con-
tact, the energy in the coil primary transfers to the
secondary causing a spark. The PCM will de-energize
the ASD relay if it does not receive inputs from
either the crankshaft or camshaft position sensors.
SPECIFICATIONS
SPECIFICATIONS - IGNITION TIMING
Ignition timing is not adjustable on any
engine.
ENGINE FIRING ORDER - 2.4L 4-CYLINDER1-3-4-2
ENGINE FIRING ORDER - 3.7L V-61-6-5-4-3-2
IGNITION COIL RESISTANCE - 2.4L
Engine Coil ManufacturePrimary Resistance at
21ÉC-27ÉC (70ÉF-80ÉF)Secondary Resistance at
21ÉC-27ÉC (70ÉF-80ÉF)
2.4L Toyodenso or Diamond 0.51 to 0.61 Ohms 11,500 to 13,500 Ohms
Fig. 1 IGNITION COIL - 2.4L
8I - 2 IGNITION CONTROLKJ
IGNITION CONTROL (Continued)

IGNITION COIL RESISTANCE - 3.7L V-6
PRIMARY RESISTANCE
21-27ÉC (70-80ÉF)SECONDARY
RESISTANCE 21-27ÉC
(70-80ÉF)
0.6 - 0.9 Ohms 6,000 - 9,000 Ohms
SPARK PLUGS
ENGINE PLUG TYPE ELECTRODE GAP
2.4L RE14MCC5 (Champion #) 1.24 to 1.37 mm (0.048 to 0.053 in.)
3.7L V-6 2FR6F - 11G (NGK #) 1.1 mm (0.042 in.)
SPARK PLUG CABLE RESISTANCE - 2.4L
MINIMUM MAXIMUM
250 Ohms Per Inch 1000 Ohms Per Inch
3000 Ohms Per Foot 12,000 Ohms Per Foot
TORQUE - IGNITION SYSTEM
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Camshaft Position Sensor-2.4L 23 21 205
Camshaft Position Sensor±3.7L 12 - 106
Crankshaft Position Sensor Bolt-2.4L 12 - 106
Crankshaft Position Sensor Nut/Bolt-3.7L 23 21 205
* Knock Sensor Bolt - 3.7L * 20 * 15
Ignition Coil Mounting Bolts - 2.4L 11 - 105
Ignition Coil Mounting Nuts - 3.7L 8 - 70
Ignition Coil Capacitor Nuts- 3.7L 8 - 70
** Spark Plugs - 2.4L ** 15 ** 11 -
Spark Plugs - 3.7L 27 20 -
* Do not apply any sealant, thread-locker or adhesive to
bolts. Poor sensor performance may result.
** Torque critical tapered design. Do not exceed 15 ft. lbs.
KJIGNITION CONTROL 8I - 3
IGNITION CONTROL (Continued)

DESCRIPTION-3.7L
The Camshaft Position Sensor (CMP) on the 3.7L
6±cylinder engine is bolted to the right-front side of
the right cylinder head (Fig. 6).
OPERATION
OPERATION - 2.4L
The Camshaft Position Sensor (CMP) sensor con-
tains a hall effect device referred to as a sync signal
generator. A rotating target wheel (tonewheel) for the
CMP is located behind the exhaust valve-camshaft
drive gear (Fig. 7). The target wheel is equipped with
a cutout (notch) around 180 degrees of the wheel.
The CMP detects this cutout every 180 degrees of
camshaft gear rotation. Its signal is used in conjunc-
tion with the Crankshaft Position Sensor (CKP) to
differentiate between fuel injection and spark events.
It is also used to synchronize the fuel injectors with
their respective cylinders.
When the leading edge of the target wheel cutout
enters the tip of the CMP, the interruption of mag-
netic field causes the voltage to switch high, result-
ing in a sync signal of approximately 5 volts.
When the trailing edge of the target wheel cutout
leaves the tip of the CMP, the change of the magnetic
field causes the sync signal voltage to switch low to 0
volts.
OPERATION - 3.7L
The Camshaft Position Sensor (CMP) sensor con-
tains a hall effect device referred to as a sync signal
generator. A rotating target wheel (tonewheel) for the
CMP is located at the front of the camshaft for the
right cylinder head (Fig. 8). This sync signal genera-
tor detects notches located on a tonewheel. As the
tonewheel rotates, the notches pass through the sync
signal generator. The signal from the CMP sensor is
used in conjunction with the Crankshaft Position
Sensor (CKP) to differentiate between fuel injection
and spark events. It is also used to synchronize the
fuel injectors with their respective cylinders.
When the leading edge of the tonewheel notch
enters the tip of the CMP, the interruption of mag-
netic field causes the voltage to switch high, result-
ing in a sync signal of approximately 5 volts.
When the trailing edge of the tonewheel notch
leaves then tip of the CMP, the change of the mag-
netic field causes the sync signal voltage to switch
low to 0 volts.
Fig. 6 CAMSHAFT POSITION SENSOR - 3.7L
1 - RIGHT/FRONT OF RIGHT CYLINDER HEAD
2 - CMP MOUNTING BOLT
3 - CMP LOCATION
Fig. 7 CMP FACE AT TARGET WHEEL-2.4L
1 - CAMSHAFT DRIVE GEAR
2 - TARGETWHEEL (TONEWHEEL)
3 - FACE OF CMP SENSOR
4 - CUTOUT (NOTCH)
8I - 6 IGNITION CONTROLKJ
CAMSHAFT POSITION SENSOR (Continued)

REMOVAL
2.4L
The Camshaft Position Sensor (CMP) on the 2.4L
4±cylinder engine is bolted to the right-front side of
the cylinder head (Fig. 9). Sensor position (depth) is
adjustable.
(1) Disconnect electrical connector at CMP sensor.
(2) Remove 2 sensor mounting bolts.
(3) Remove sensor from cylinder head by sliding
towards rear of engine.
3.7L
The Camshaft Position Sensor (CMP) on the 3.7L
V-6 engine is bolted to the front/top of the right cyl-
inder head (Fig. 10).
(1) Disconnect electrical connector at CMP sensor.
(2) Remove sensor mounting bolt (Fig. 10).
(3) Carefully remove sensor from cylinder head in
a rocking and twisting action. Twisting sensor eases
removal.
(4) Check condition of sensor o-ring.
Fig. 8 CAMSHAFT POSITION SENSOR LOCATION -
3.7L
1 - NOTCHES
2 - RIGHT CYLINDER HEAD
3 - CMP
4 - TONEWHEEL (TARGET WHEEL)
Fig. 9 CMP LOCATION - 2.4L
1 - CMP SENSOR
2 - ELECTRICAL CONNECTOR
3-
4 - SLOTTED HOLES
5 - MOUNTING BOLTS (2)
Fig. 10 CAMSHAFT POSITION SENSOR (CMP) - 3.7L
1 - RIGHT/FRONT OF RIGHT CYLINDER HEAD
2 - CMP MOUNTING BOLT
3 - CMP LOCATION
KJIGNITION CONTROL 8I - 7
CAMSHAFT POSITION SENSOR (Continued)

3.7L
The Camshaft Position Sensor (CMP) on the 3.7L
V-6 engine is bolted to the front/top of the right cyl-
inder head.
(1) Clean out machined hole in cylinder head.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into cylinder head with a slight
rocking and twisting action.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder head.
If sensor is not flush, damage to sensor mounting
tang may result.
(4) Install mounting bolt and tighten. Refer to
torque specifications.
(5) Connect electrical connector to sensor.
IGNITION COIL
DESCRIPTION
2.4L
The coil assembly consists of 2 different coils
molded together. The assembly is mounted to the top
of the engine (Fig. 14).
3.7L
The 3.7L V-6 engine uses 6 dedicated, and individ-
ually fired coil for each spark plug (Fig. 15). Each
coil is mounted directly into the cylinder head and
onto the top of each spark plug (Fig. 16).
OPERATION
2.4L
The coil fires two spark plugs simultaneously. One
plug is under compression, the other plug fires on the
exhaust stroke (lost spark). Coil number one fires
Fig. 14 IGNITION COIL - 2.4L
1 - IGNITION COIL
2 - MOUNTING BOLTS (4)
Fig. 15 IGNITION COIL - 3.7L
1 - O-RING
2 - IGNITION COIL
3 - ELECTRICAL CONNECTOR
Fig. 16 IGNITION COIL LOCATION - 3.7L
1 - IGNITION COIL
2 - COIL MOUNTING NUT
KJIGNITION CONTROL 8I - 9
CAMSHAFT POSITION SENSOR (Continued)

cylinders 1 and 4, and coil number two fires cylinders
2 and 3.
The Auto Shutdown (ASD) relay provides battery
voltage to the ignition coil. The PCM provides a
ground contact (circuit) for energizing the coil(s). The
PCM will de-energize the ASD relay if it does not
receive the crankshaft position sensor and camshaft
position sensor inputs.
Base ignition timing is not adjustable.By con-
trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper-
ating conditions.
The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.
Spark plug cables (secondary wires or cables) are
used with the 2.4L engine.
3.7L
Battery voltage is supplied to the 6 ignition coils
from the ASD relay. The Powertrain Control Module
(PCM) opens and closes each ignition coil ground cir-
cuit at a determined time for ignition coil operation.
Base ignition timing is not adjustable.By con-
trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper-
ating conditions.
The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.
Because of coil design, spark plug cables (second-
ary cables) are not used with the 3.7L engine.
REMOVAL
2.4L
(1) Disconnect electrical connector at rear of coil.
(2) Remove all secondary cables from coil.
(3) Remove 4 coil mounting bolts (Fig. 17).
(4) Remove coil from vehicle.
3.7L
An individual ignition coil is used for each spark
plug (Fig. 19). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 18). The bot-
tom of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.19) is used to seal the coil at the opening into the cyl-
inder head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector from coil by
pushing downward on release lock on top of connec-
tor and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
(4) Remove coil mounting nut from mounting stud
(Fig. 18).
(5) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(6) Remove coil from vehicle.
INSTALLATION
2.4L
(1) Position coil to engine.
(2) Install 4 mounting bolts. Refer to torque speci-
fications.
(3) Install secondary cables.
(4) Install electrical connector at rear of coil.
(5) Install air cleaner tube and housing.
3.7L
(1) Using compressed air, blow out any dirt or con-
taminants from around top of spark plug.
(2) Check condition of coil o-ring and replace as
necessary. To aid in coil installation, apply silicone to
coil o-ring.
Fig. 17 IGNITION COIL - 2.4L
1 - IGNITION COIL
2 - MOUNTING BOLTS (4)
8I - 10 IGNITION CONTROLKJ
IGNITION COIL (Continued)