2002 JEEP LIBERTY charging

SPECIAL TOOLS
BATTERY TEMPERATURE
SENSOR
DESCRIPTION
The Battery Temperature Sensor (BTS) is attached
to the battery tray located under the battery.
OPERATION
The BTS is used to determine the battery temper-
ature and control battery charging rate. This temper-
ature data, along with data from monitored line
voltage, is used by the PCM to vary the battery
charging rate. System voltage will be higher at colder
temperatures and is gradually reduced at warmer
temperatures.
The PCM sends 5 volts to the sensor and is
grounded through the sensor return line. As temper-
ature increases, resistance in the sensor decreases
and the detection voltage at the PCM increases.The BTS is also used for OBD II diagnostics. Cer-
tain faults and OBD II monitors are either enabled
or disabled, depending upon BTS input (for example,
disable purge and enable Leak Detection Pump
(LDP) and O2 sensor heater tests). Most OBD II
monitors are disabled below 20 degrees F.
REMOVAL
The battery temperature sensor is located under
the vehicle battery (Fig. 1) and is attached to a
mounting hole on battery tray.
(1) Remove battery. Refer to 8, Battery for proce-
dures.
(2) Disconnect sensor pigtail harness from engine
wire harness electrical connector.
(3) Pry sensor straight up from battery tray
mounting hole.
INSTALLATION
The battery temperature sensor is located under
vehicle battery and is attached to a mounting hole on
battery tray.
(1) Feed pigtail harness through hole in top of bat-
tery tray and press sensor into top of battery tray.
(2) Connect pigtail harness.
(3) Install battery. Refer to 8, Battery for proce-
dures.
GENERATOR DECOUPLER TOOL #8433
GENERATOR DECOUPLER TOOL #8823
Fig. 1 BATTERY TEMPERATURE SENSOR
1 - BATTERY TEMPERATURE SENSOR
2 - BATTERY TRAY
3 - ELECTRICAL CONNECTOR
8F - 24 CHARGING SYSTEMKJ
CHARGING SYSTEM (Continued)

GENERATOR
DESCRIPTION
The generator is belt-driven by the engine using a
serpentine type drive belt. It is serviced only as a
complete assembly. If the generator fails for any rea-
son, the entire assembly must be replaced.
OPERATION
As the energized rotor begins to rotate within the
generator, the spinning magnetic field induces a cur-
rent into the windings of the stator coil. Once the
generator begins producing sufficient current, it also
provides the current needed to energize the rotor.
The stator winding connections deliver the induced
AC current to 3 positive and 3 negative diodes for
rectification. From the diodes, rectified DC current is
delivered to the vehicle electrical system through the
generator battery terminal.
Although the generators appear the same exter-
nally, different generators with different output rat-
ings are used on this vehicle. Be certain that the
replacement generator has the same output rating
and part number as the original unit. Refer to Spec-
ifications and see Generator Ratings for amperage
ratings and part numbers.
Noise emitting from the generator may be caused
by: worn, loose or defective bearings; a loose or defec-
tive drive pulley; incorrect, worn, damaged or misad-
justed fan drive belt; loose mounting bolts; a
misaligned drive pulley or a defective stator or diode.
REMOVAL
Gasoline Powered Engines
CAUTION: DISCONNECT NEGATIVE CABLE FROM
BATTERY BEFORE REMOVING BATTERY OUTPUT
WIRE FROM GENERATOR. FAILURE TO DO SO
CAN RESULT IN INJURY.
(1) Disconnect and isolate negative battery cable
at battery.
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 Cooling
System.
(2) Remove generator drive belt. Refer to 7, Cool-
ing System for procedures.
(3) Unsnap plastic protective cover (Fig. 2) from
B+ mounting stud.
(4) Remove B+ terminal mounting nut (Fig. 2) at
top of generator.
(5) Disconnect field wire electrical connector at
rear of generator (Fig. 2) by pushing on connector
tab.
(6) 2.4L Engine: Remove 2 generator mounting
bolts (Fig. 3).
(7) 3.7L Engine: Remove 1 vertical generator
mounting bolt and 2 horizontal mounting bolts (Fig.
4).
(8) Remove generator from vehicle.
Fig. 2 GENERATOR ELECTRICAL CONNECTORS -
TYPICAL
1 - PROTECTIVE CAP
2-B+NUT
3 - B+ TERMINAL
4 - FIELD ELECTRICAL CONNECTOR
KJCHARGING SYSTEM 8F - 25

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)

OPERATION
The generator decoupler is used only with
certain engines.The decoupler (Fig. 5). is a one-
way clutch designed to help reduce belt tension fluc-
tuation, vibration, reduce fatigue loads, improve belt
life, reduce hubloads on components, and reduce
noise. Dry operation is used (no grease or lubricants).
The decoupler is not temperature sensitive and also
has a low sensitivity to electrical load. The decoupler
is a non-serviceable item and is to be replaced as an
assembly.
DIAGNOSIS AND TESTING - GENERATOR DECOUPLER
CONDITION POSSIBLE CAUSES CORRECTION
Does not drive generator (generator not charging) Internal failure Replace decoupler
Noise coming from decoupler Internal failure Replace decoupler
REMOVAL
The generator decoupler is used only with
certain engines.
Two different type generator decoupler pulleys are
used. One can be identified by the use of machined
splines (Fig. 6). The other can be identified by a hex
opening (Fig. 7) and will not use splines.
Different special tools are required to service each
different decoupler. Refer to following procedure.
INA Decoupler
(1) Disconnect negative battery cable.
(2) Remove generator and accessory drive belt.
Refer to Generator Removal.
(3) Position Special Tool #8823 (VM.1048) into
decoupler (Fig. 8).
(4) Determine if end of generator shaft is hex
shaped (Fig. 9) or is splined (Fig. 10). If hex is used,
insert a 10MM deep socket into tool #8823 (VM.1048)
(Fig. 11). If splined, insert a 5/16º 6-point hex driver,
or a 10MM 12-point triple square driver into tool
#8823 (VM.1048) (Fig. 12).
(5) The generator shaft uses conventional right-
hand threads to attach decoupler. To break decoupler
loose from generator threads, rotate end of tool clock-
wise (Fig. 11) or, (Fig. 12).(6) After breaking loose with tool, unthread decou-
pler by hand from generator.
Fig. 5 GENERATOR DECOUPLER PULLEY
(TYPICAL)
Fig. 6 GENERATOR DECOUPLER PULLEY (INA)
1 - GENERATOR
2 - DECOUPLER (INA)
3 - MACHINED SPLINES
KJCHARGING SYSTEM 8F - 27
GENERATOR DECOUPLER PULLEY (Continued)

Fig. 7 GENERATOR DECOUPLER PULLEY (LITENS)
1 - DECOUPLER (LITENS)
2 - HEX OPENING
Fig. 8 #8823 (VM.1048) TOOL AND INA DECOUPLER
1 - INA DECOUPLER
2 - TOOL #8823 (VM.1048)
Fig. 9 END OF GENERATOR SHAFT (HEX)
1 - GENERATOR SHAFT
2 - HEX
Fig. 10 END OF GENERATOR SHAFT (SPLINED)
1 - GENERATOR SHAFT
2 - SPLINES
8F - 28 CHARGING SYSTEMKJ
GENERATOR DECOUPLER PULLEY (Continued)

Litens Decoupler
(1) Disconnect negative battery cable.(2) Remove generator and accessory drive belt.
Refer to Generator Removal.
(3) Position Special Tool #8433 (Fig. 13) into
decoupler. Align to hex end of generator shaft.
(4) The generator shaft uses conventional right-
hand threads to attach decoupler. To break decoupler
loose from generator threads, rotate end of tool clock-
wise (Fig. 14).
(5) After breaking loose with tool, unthread decou-
pler by hand from generator.
Fig. 11 DECOUPLER REMOVAL (INA-HEX)
1 - DEEP 10 MM SOCKET
2 - TOOL #8823 (VM.1048)
Fig. 12 DECOUPLER REMOVAL (INA-SPLINED)
1 - DRIVER
2 - TOOL #8823 (VM.1048)
3 - 17 MM WRENCH
Fig. 13 # 8433 TOOL AND LITENS DECOUPLER
Fig. 14 DECOUPLER REMOVAL (LITENS)
KJCHARGING SYSTEM 8F - 29
GENERATOR DECOUPLER PULLEY (Continued)

INSTALLATION
INA Decoupler
(1) Thread decoupler pulley onto generator shaft
by hand (right-hand threads).
(2) Position Special Tool #8823 (VM.1048) into
decoupler (Fig. 8).
(3) Determine if end of generator shaft is hex
shaped (Fig. 9) or is splined (Fig. 10). If hex is used,
insert a 10MM deep socket into tool #8823 (VM.1048)
(Fig. 15). If splined, insert a 5/16º 6-point hex driver,
or a 10MM 12-point triple square driver into tool
#8823 (VM.1048) (Fig. 16).
(4)Do not use an adjustable, ratcheting ªclick
typeº torque wrench. Most ªclick typeº
wrenches will only allow torque to be applied
in a clockwise rotation. Use a dial-type or
beam-type wrench.Tighten in counter-clockwise
rotation (Fig. 15) or, (Fig. 16). Refer to torque speci-
fications.
(5) Install accessory drive belt, and generator.
Refer to Generator Installation.
(6) Connect negative battery cable.
Litens Decoupler
(1) Thread decoupler pulley onto generator shaft
by hand (right-hand threads).
(2) Position Special Tool 8433 (Fig. 13) into decou-
pler. Align tool to hex end of generator shaft.
(3)Do not use an adjustable, ratcheting ªclick
typeº torque wrench. Most ªclick typeº
wrenches will only allow torque to be applied
in a clockwise rotation. Use a dial-type orbeam-type wrench.Tighten in counter-clockwise
rotation (Fig. 17). Refer to torque specifications.
(4) Install accessory drive belt, and generator.
Refer to Generator Installation.
(5) Connect negative battery cable.
Fig. 15 DECOUPLER INSTALLATION (INA-HEX)
1 - 10MM DEEP SOCKET
2 - TOOL # 8823 (VM.1048)
Fig. 16 DECOUPLER INSTALLATION (INA SPLINED)
1 - DRIVER
2 - TOOL # 8823 (VM.1048)
Fig. 17 DECOUPLER INSTALLATION (Litens)
8F - 30 CHARGING SYSTEMKJ
GENERATOR DECOUPLER PULLEY (Continued)

VOLTAGE REGULATOR
DESCRIPTION
The Electronic Voltage Regulator (EVR) is not a
separate component. It is actually a voltage regulat-
ing circuit located within the Powertrain Control
Module (PCM). The EVR is not serviced separately. If
replacement is necessary, the PCM must be replaced.
OPERATION
The amount of DC current produced by the gener-
ator is controlled by EVR circuitry contained within
the Powertrain Control Module (PCM). This circuitry
is connected in series with the generators second
rotor field terminal and its ground.
Voltage is regulated by cycling the ground path to
control the strength of the rotor magnetic field. TheEVR circuitry monitors system line voltage (B+) and
battery temperature (refer to Battery Temperature
Sensor for more information). It then determines a
target charging voltage. If sensed battery voltage is
0.5 volts or lower than the target voltage, the PCM
grounds the field winding until sensed battery volt-
age is 0.5 volts above target voltage. A circuit in the
PCM cycles the ground side of the generator field up
to 100 times per second (100Hz), but has the capabil-
ity to ground the field control wire 100% of the time
(full field) to achieve the target voltage. If the charg-
ing rate cannot be monitored (limp-in), a duty cycle
of 25% is used by the PCM in order to have some
generator output. Also refer to Charging Operation
for additional information.
KJCHARGING SYSTEM 8F - 31