2002 JEEP LIBERTY engine oil

economy, and/or trip odometer data has been reset.
The CMTC uses internal programming, hard wired
inputs from the U.S./Metric and Reset switches, and
electronic messages received from the Body Control
Module (BCM) to determine the proper reset mes-
sages to send to the EMIC.
²Door Ajar Warning- The EMIC chime tone
generator will generate a single ªbong-likeº chime
tone when the ignition switch is in the On position,
and electronic messages are received over the PCI
data bus from the Body Control Module (BCM) indi-
cating that the status of any door ajar input has
changed from closed to not closed, and from the PCM
indicating that the vehicle is moving. The BCM uses
internal programming, and hard wired inputs from
the door ajar switches and the ignition switch to
determine the proper door ajar switch messages to
send to the EMIC. The PCM uses internal program-
ming and a hard wired vehicle speed pulse input
received from the BCM to determine the proper vehi-
cle distance messages to send to the EMIC.
²Electrical System Voltage Low or High
Warning- Each time the ignition switch is turned to
the On position, the EMIC chime tone generator will
generate a single ªbong-likeº chime tone the first
time an electronic message is received over the PCI
data bus from the PCM requesting ªChargingº indi-
cator illumination. This warning would indicate that
the monitored electrical system voltage is either too
low or too high. This warning will only occur once
during an ignition cycle. The PCM uses internal pro-
gramming and hard wired inputs from the electrical
and charging systems to determine the proper
ªChargingº indicator messages to send to the EMIC.
²Engine Coolant Temperature High Warning
- Each time the ignition switch is turned to the On
position, the EMIC chime tone generator will gener-
ate ªbong-likeº chime tones the first time an elec-
tronic message is received over the PCI data bus
from the PCM indicating that the engine coolant
temperature is too high. This chime will sound for
five consecutive single tones, unless an electronic
message is received from the PCM indicating that
the engine coolant temperature is not too high, or
unless the ignition switch is turned to the Off posi-
tion before the five single tones have completed. The
PCM uses internal programming and a hard wired
input from the engine coolant temperature sensor to
determine the proper engine coolant temperature
messages to send to the EMIC.
²Engine Oil Pressure Low Warning- Each
time the ignition switch is turned to the On position,
the EMIC chime tone generator will generate a sin-
gle ªbong-likeº chime tone the first time three
sequential sets of electronic messages are received
over the PCI data bus from the PCM indicating thatthe engine oil pressure is too low with the engine
running. The PCM uses internal programming and
hard wired inputs from the oil pressure sensor and
the crankshaft position sensor to determine the
proper oil pressure and engine speed messages to
send to the EMIC.
²Fasten Seat Belt Warning- Each time the
ignition switch is turned to the On position, the
EMIC chime tone generator will generate repetitive
ªbong-likeº chime tones at a slow rate the first time
an electronic message is received over the PCI data
bus from the ACM requesting ªSeatbeltº indicator
illumination. The ACM uses internal programming
and hard wired inputs from the driver side front seat
belt switch and the ignition switch to determine that
the driver side front seat belt is not fastened with
the ignition switch in the On position. These chimes
will continue to sound for a duration of about six sec-
onds each time the ignition switch is turned to the
On position, or until the driver side front seat belt is
fastened, whichever occurs first. This audible warn-
ing occurs independent of the visual warning pro-
vided by the EMIC ªSeatbeltº indicator.
²Gate Ajar Warning- The EMIC chime tone
generator will generate a single ªbong-likeº chime
tone when the ignition switch is in the On position,
and electronic messages are received over the PCI
data bus from the BCM indicating that the status of
the tailgate ajar input has changed from closed to
not closed, and from the PCM indicating that the
vehicle is moving. The BCM uses internal program-
ming, and hard wired inputs from the tailgate ajar
switch and the ignition switch to determine the
proper tailgate ajar switch messages to send to the
EMIC. The PCM uses internal programming and a
hard wired vehicle speed pulse input received from
the BCM to determine the proper vehicle distance
messages to send to the EMIC.
²Glass Ajar Warning- The EMIC chime tone
generator will generate a single ªbong-likeº chime
tone when the ignition switch is in the On position,
and electronic messages are received over the PCI
data bus from the BCM indicating that the status of
the rear flip-up glass ajar input has changed from
closed to not closed, and from the PCM indicating
that the vehicle is moving. The BCM uses internal
programming, and hard wired inputs from the flip-up
glass ajar switch and the ignition switch to deter-
mine the proper flip-up glass ajar switch messages to
send to the EMIC. The PCM uses internal program-
ming and a hard wired vehicle speed pulse input
received from the BCM to determine the proper vehi-
cle distance messages to send to the EMIC.
²Head/Park/Fog Lights-On Warning- The
EMIC chime tone generator will generate repetitive
ªbong-likeº chime tones at a fast rate when the igni-
KJCHIME/BUZZER 8B - 3
CHIME WARNING SYSTEM (Continued)

²Battery voltage
²Engine coolant temperature sensor
²Crankshaft position sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal
²Park/neutral switch (gear indicator signalÐauto.
trans. only)
²Oxygen (O2S) sensors
Based on these inputs, the following occurs:
²Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then adjust
the injector pulse width by turning the ground circuit
to each individual injector on and off.
²The PCM monitors the O2S sensor input and
adjusts air-fuel ratio. It also adjusts engine idle
speed through the idle air control (IAC) motor.
²The PCM adjusts ignition timing by turning the
ground path to the coil(s) on and off.
²The PCM operates the A/C compressor clutch
through the clutch relay. This happens if A/C has
been selected by the vehicle operator and requested
by the A/C thermostat.
ACCELERATION MODE
This is an Open Loop mode. The PCM recognizes
an abrupt increase in throttle position or MAP pres-
sure as a demand for increased engine output and
vehicle acceleration. The PCM increases injector
pulse width in response to increased throttle opening.
DECELERATION MODE
When the engine is at operating temperature, this
is an Open Loop mode. During hard deceleration, the
PCM receives the following inputs.
²Air conditioning select signal (if equipped)
²Air conditioning request signal (if equipped)
²Battery voltage
²Engine coolant temperature sensor
²Crankshaft position sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal
²Park/neutral switch (gear indicator signalÐauto.
trans. only)
²Vehicle speed
If the vehicle is under hard deceleration with the
proper rpm and closed throttle conditions, the PCM
will ignore the oxygen sensor input signal. The PCM
will enter a fuel cut-off strategy in which it will not
supply a ground to the injectors. If a hard decelera-
tion does not exist, the PCM will determine the
proper injector pulse width and continue injection.Based on the above inputs, the PCM will adjust
engine idle speed through the idle air control (IAC)
motor.
The PCM adjusts ignition timing by turning the
ground path to the coil on and off.
WIDE OPEN THROTTLE MODE
This is an Open Loop mode. During wide open
throttle operation, the PCM receives the following
inputs.
²Battery voltage
²Crankshaft position sensor
²Engine coolant temperature sensor
²Intake manifold air temperature sensor
²Manifold absolute pressure (MAP) sensor
²Throttle position sensor (TPS)
²Camshaft position sensor signal
During wide open throttle conditions, the following
occurs:
²Voltage is applied to the fuel injectors with the
ASD relay via the PCM. The PCM will then control
the injection sequence and injector pulse width by
turning the ground circuit to each individual injector
on and off. The PCM ignores the oxygen sensor input
signal and provides a predetermined amount of addi-
tional fuel. This is done by adjusting injector pulse
width.
²The PCM adjusts ignition timing by turning the
ground path to the coil(s) on and off.
IGNITION SWITCH OFF MODE
When ignition switch is turned to OFF position,
the PCM stops operating the injectors, ignition coil,
ASD relay and fuel pump relay.
DESCRIPTION - 5 VOLT SUPPLIES
Two different Powertrain Control Module (PCM)
five volt supply circuits are used; primary and sec-
ondary.
DESCRIPTION - IGNITION CIRCUIT SENSE
This circuit ties the ignition switch to the Power-
train Control Module (PCM).
DESCRIPTION - POWER GROUNDS
The Powertrain Control Module (PCM) has 2 main
grounds. Both of these grounds are referred to as
power grounds. All of the high-current, noisy, electri-
cal devices are connected to these grounds as well as
all of the sensor returns. The sensor return comes
into the sensor return circuit, passes through noise
suppression, and is then connected to the power
ground.
The power ground is used to control ground cir-
cuits for the following PCM loads:
²Generator field winding
KJELECTRONIC CONTROL MODULES 8E - 13
POWERTRAIN CONTROL MODULE (Continued)

²Fuel injectors
²Ignition coil(s)
²Certain relays/solenoids
²Certain sensors
DESCRIPTION - SENSOR RETURN
The Sensor Return circuits are internal to the Pow-
ertrain Control Module (PCM).
Sensor Return provides a low±noise ground refer-
ence for all engine control system sensors. Refer to
Power Grounds for more information.
OPERATION
OPERATION - PCM
The PCM operates the fuel system. The PCM is a
pre-programmed, triple microprocessor digital com-
puter. It regulates ignition timing, air-fuel ratio,
emission control devices, charging system, certain
transmission features, speed control, air conditioning
compressor clutch engagement and idle speed. The
PCM can adapt its programming to meet changing
operating conditions.
The PCM receives input signals from various
switches and sensors. Based on these inputs, the
PCM regulates various engine and vehicle operations
through different system components. These compo-
nents are referred to as Powertrain Control Module
(PCM) Outputs. The sensors and switches that pro-
vide inputs to the PCM are considered Powertrain
Control Module (PCM) Inputs.
The PCM adjusts ignition timing based upon
inputs it receives from sensors that react to: engine
rpm, manifold absolute pressure, engine coolant tem-
perature, throttle position, transmission gear selec-
tion (automatic transmission), vehicle speed, power
steering pump pressure, and the brake switch.
The PCM adjusts idle speed based on inputs it
receives from sensors that react to: throttle position,
vehicle speed, transmission gear selection, engine
coolant temperature and from inputs it receives from
the air conditioning clutch switch and brake switch.
Based on inputs that it receives, the PCM adjusts
ignition coil dwell. The PCM also adjusts the gener-
ator charge rate through control of the generator
field and provides speed control operation.
NOTE: PCM Inputs:
²A/C request (if equipped with factory A/C)
²A/C select (if equipped with factory A/C)
²A/C pressure transducer
²Auto shutdown (ASD) sense
²Battery temperature
²Battery voltage
²Brake switch²J1850 bus (+) circuits
²J1850 bus (-) circuits
²Camshaft position sensor signal
²Crankshaft position sensor
²Data link connection for DRB scan tool
²Engine coolant temperature sensor
²Fuel level (through J1850 circuitry)
²Generator (battery voltage) output
²Ignition circuit sense (ignition switch in on/off/
crank/run position)
²Intake manifold air temperature sensor
²Knock sensors (2 on 3.7L engine)
²Leak detection pump (switch) sense (if equipped)
²Manifold absolute pressure (MAP) sensor
²Oil pressure
²Oxygen sensors
²Park/neutral switch (auto. trans. only)
²Power ground
²Power steering pressure switch
²Sensor return
²Signal ground
²Speed control multiplexed single wire input
²Throttle position sensor
²Transfer case switch (4WD range position)
²Vehicle speed sensor
NOTE: PCM Outputs:
²A/C clutch relay
²Auto shutdown (ASD) relay
²J1850 bus (+/-) circuits for: speedometer, voltme-
ter, fuel gauge, oil pressure gauge/lamp, engine temp.
gauge and speed control warn. lamp
²Clutch pedal position switch override relay
²Data link connection for DRB scan tool
²EGR valve control solenoid (if equipped)
²EVAP canister purge solenoid
²Five volt sensor supply (primary)
²Five volt sensor supply (secondary)
²Fuel injectors
²Fuel pump relay
²Generator field driver (-)
²Generator field driver (+)
²Idle air control (IAC) motor
²Ignition coil(s)
²Leak detection pump (if equipped)
²Malfunction indicator lamp (Check engine lamp).
Driven through J1850 circuits.
²Oxygen sensor heater relays
²Oxygen sensors (pulse width modulated)
²Radiator cooling fan relay (pulse width modu-
lated)
²Speed control vacuum solenoid
²Speed control vent solenoid
²Tachometer (if equipped). Driven through J1850
circuits.
8E - 14 ELECTRONIC CONTROL MODULESKJ
POWERTRAIN CONTROL MODULE (Continued)

²Transmission convertor clutch circuit. Driven
through J1850 circuits.
OPERATION - 5 VOLT SUPPLIES
Primary 5±volt supply:
²supplies the required 5 volt power source to the
Crankshaft Position (CKP) sensor.
²supplies the required 5 volt power source to the
Camshaft Position (CMP) sensor.
²supplies a reference voltage for the Manifold
Absolute Pressure (MAP) sensor.
²supplies a reference voltage for the Throttle
Position Sensor (TPS) sensor.
Secondary 5±volt supply:
²supplies the required 5 volt power source to the
oil pressure sensor.
²supplies the required 5 volt power source for the
Vehicle Speed Sensor (VSS) (if equipped).
²supplies the 5 volt power source to the transmis-
sion pressure sensor (certain automatic transmis-
sions).
OPERATION - IGNITION CIRCUIT SENSE
The ignition circuit sense input tells the PCM the
ignition switch has energized the ignition circuit.
Battery voltage is also supplied to the PCM
through the ignition switch when the ignition is in
the RUN or START position. This is referred to as
the9ignition sense9circuit and is used to9wake up9
the PCM. Voltage on the ignition input can be as low
as 6 volts and the PCM will still function. Voltage is
supplied to this circuit to power the PCM's 8-volt reg-
ulator and to allow the PCM to perform fuel, ignition
and emissions control functions.
REMOVAL
USE THE DRB SCAN TOOL TO REPROGRAM
THE NEW POWERTRAIN CONTROL MODULE
(PCM) WITH THE VEHICLES ORIGINAL IDEN-
TIFICATION NUMBER (VIN) AND THE VEHI-
CLES ORIGINAL MILEAGE. IF THIS STEP IS
NOT DONE, A DIAGNOSTIC TROUBLE CODE
(DTC) MAY BE SET.
The PCM is located in the engine compartment
near the battery (Fig. 9).
To avoid possible voltage spike damage to the
PCM, ignition key must be off, and negative battery
cable must be disconnected before unplugging PCM
connectors.
(1) Disconnect negative battery cable at battery.
(2) Remove cover over electrical connectors. Cover
snaps onto PCM.
(3) Carefully unplug the three 32±way connectors
from PCM.
(4) Remove three PCM mounting bolts and remove
PCM from vehicle.
INSTALLATION
USE THE DRB SCAN TOOL TO REPROGRAM
THE NEW POWERTRAIN CONTROL MODULE
(PCM) WITH THE VEHICLES ORIGINAL IDEN-
TIFICATION NUMBER (VIN) AND THE VEHI-
CLES ORIGINAL MILEAGE. IF THIS STEP IS
NOT DONE, A DIAGNOSTIC TROUBLE CODE
(DTC) MAY BE SET.
(1) Install PCM and 3 mounting bolts to vehicle.
(2) Tighten bolts. Refer to torque specifications.
(3) Check pin connectors in the PCM and the three
32±way connectors for corrosion or damage. Also, the
pin heights in connectors should all be same. Repair
as necessary before installing connectors.
(4) Install three 32±way connectors.
(5) Install cover over electrical connectors. Cover
snaps onto PCM.
(6) Install battery cable.
(7) Use the DRB scan tool to reprogram new PCM
with vehicles original Identification Number (VIN)
and original vehicle mileage.
SENTRY KEY IMMOBILIZER
MODULE
DESCRIPTION
The Sentry Key Immobilizer Module (SKIM) is the
primary component of the Sentry Key Immobilizer
System (SKIS) (Fig. 10). The SKIM is located on the
right side of the steering column, below the ignition
Fig. 9 PCM REMOVE/INSTALL
1 - PCM
2 - MOUNTING BOLTS (3)
3 - 32-WAY CONNECTORS
KJELECTRONIC CONTROL MODULES 8E - 15
POWERTRAIN CONTROL MODULE (Continued)

Certain mechanical problems within the input
clutch assembly (broken return springs, out of posi-
tion snap rings, excessive clutch pack clearance,
improper assembly, etc.) can cause inadequate or out-
of-range element volumes. Also, defective Input/Out-
put Speed Sensors and wiring can cause these
conditions. The following chart identifies the appro-
priate clutch volumes and when they are monitored/
updated:
CLUTCH VOLUMES
Clutch When UpdatedProper Clutch
Volume
L/R2-1 or 3-1
downshift45 to 134
2C3-2 kickdown
shift25 to 85
OD 2-3 upshift 30 to 100
CLUTCH VOLUMES
4C 3-4 upshift 30 to 85
UD4-3 kickdown
shift30 to 100
SHIFT SCHEDULES
As mentioned earlier, the TCM has programming
that allows it to select a variety of shift schedules.
Shift schedule selection is dependent on the follow-
ing:
²Shift lever position
²Throttle position
²Engine load
²Fluid temperature
²Software level
As driving conditions change, the TCM appropri-
ately adjusts the shift schedule. Refer to the follow-
ing chart to determine the appropriate operation
expected, depending on driving conditions.
Schedule Condition Expected Operation
Extreme ColdOil temperature below -16É F -Park, Reverse, Neutral and 1st and
3rd gear only in D position, 2nd
gear only in Manual 2 or L
-No EMCC
Super ColdOil temperature between -12É F and
10É F- Delayed 2-3 upshift
- Delayed 3-4 upshift
- Early 4-3 coastdown shift
- High speed 4-2, 3-2, 2-1 kickdown
shifts are prevented
-Shifts at high throttle openings willl
be early.
- No EMCC
ColdOil temperature between 10É F and
36É F-Shift schedule is the same as
Super Cold except that the 2-3
upshifts are not delayed.
WarmOil temperature between 40É F and
80É F- Normal operation (upshift,
kickdowns, and coastdowns)
- No EMCC
HotOil temperature between 80É F and
240É F- Normal operation (upshift,
kickdowns, and coastdowns)
- Normal EMCC operation
8E - 20 ELECTRONIC CONTROL MODULESKJ
TRANSMISSION CONTROL MODULE (Continued)

Schedule Condition Expected Operation
OverheatOil temperature above 240É F or
engine coolant temperature above
244É F- Delayed 2-3 upshift
- Delayed 3-4 upshift
- 3rd gear FEMCC from 30-48 mph
- 3rd gear PEMCC above 35 mph
- Above 25 mph the torque
converter will not unlock unless the
throttle is closed or if a wide open
throttle 2nd PEMCC to 1 kickdown
is made
STANDARD PROCEDURE - TCM QUICK LEARN
The quick learn procedure requires the use of the
DRBtscan tool.
This program allows the electronic transmission
system to recalibrate itself. This will provide the
proper transmission operation. The quick learn pro-
cedure should be performed if any of the following
procedures are performed:
²Transmission Assembly Replacement
²Transmission Control Module Replacement
²Solenoid Pack Replacement
²Clutch Plate and/or Seal Replacement
²Valve Body Replacement or Recondition
To perform the Quick Learn Procedure, the follow-
ing conditions must be met:
²The brakes must be applied
²The engine speed must be above 500 rpm
²The throttle angle (TPS) must be less than 3
degrees
²The shift lever position must stay in PARK until
prompted to shift to overdrive
²The shift lever position must stay in overdrive
after the Shift to Overdrive prompt until the DRBt
indicates the procedure is complete
²The calculated oil temperature must be above
60É and below 200É
HEATED SEAT MODULE
DESCRIPTION
The heated seat module is also known as the Seat
Heat Interface Module. The heated seat module (Fig.
14) is located under the left front seat cushion, where
it is secured to a mounting bracket via two push-pin
retainers. The heated seat module has a single con-
nector receptacle that allows the module to be con-
nected to all of the required inputs and outputs
through the seat wire harness.
The heated seat module is an electronic micropro-
cessor controlled device designed and programmed to
use inputs from the heated seat relay, the two heatedseat switches and the two heated seat sensors to
operate and control the heated seat elements in both
front seats and the two heated seat indicator lamp
Light-Emitting Diodes (LEDs) in each heated seat
switch. The heated seat module is also programmed
to perform self-diagnosis of certain heated seat sys-
tem functions and provide feedback of that diagnosis
through the heated seat switch indicator lamps.
The heated seat module cannot be repaired. If the
heated seat module is damaged or faulty, the entire
module must be replaced.
OPERATION
The heated seat module operates on fused battery
current received from a fuse in the junction block.
The module is grounded at all times. Inputs to the
module include a resistor multiplexed heated seat
switch request circuit for each of the two heated seat
switches and the heated seat sensor inputs from the
seat cushions of each front seat. In response to those
inputs, the heated seat module controls battery cur-
rent to the heated seat elements and sensors, and
Fig. 14 Heated Seat Module
1 - Mounting Tabs (Not Used On KJ)
2 - Heated Seat Module
3 - Connector Receptacle
KJELECTRONIC CONTROL MODULES 8E - 21
TRANSMISSION CONTROL MODULE (Continued)

battery charging should only be performed when
absolutely necessary due to time restraints. A battery
is fully-charged when:
²All of the battery cells are gassing freely during
battery charging.
²A green color is visible in the sight glass of the
battery built-in test indicator.
²Three hydrometer tests, taken at one-hour inter-
vals, indicate no increase in the temperature-cor-
rected specific gravity of the battery electrolyte.
²Open-circuit voltage of the battery is 12.65 volts
or above.
WARNING: NEVER EXCEED TWENTY AMPERES
WHEN CHARGING A COLD (-1É C [30É F] OR
LOWER) BATTERY. THE BATTERY MAY ARC INTER-
NALLY AND EXPLODE. PERSONAL INJURY AND/OR
VEHICLE DAMAGE MAY RESULT.
CAUTION: Always disconnect and isolate the bat-
tery negative cable before charging a battery. Do
not exceed sixteen volts while charging a battery.
Damage to the vehicle electrical system compo-
nents may result.
CAUTION: Battery electrolyte will bubble inside the
battery case during normal battery charging. Elec-
trolyte boiling or being discharged from the battery
vents indicates a battery overcharging condition.
Immediately reduce the charging rate or turn off the
charger to evaluate the battery condition. Damage
to the battery may result from overcharging.
CAUTION: The battery should not be hot to the
touch. If the battery feels hot to the touch, turn off
the charger and let the battery cool before continu-
ing the charging operation. Damage to the battery
may result.
NOTE: Models equipped with the diesel engine
option are equipped with two 12-volt batteries, con-
nected in parallel (positive-to-positive and negative-
to-negative). In order to ensure proper charging of
each battery, these batteries MUST be disconnected
from each other, as well as from the vehicle electri-
cal system, while being charged.
Some battery chargers are equipped with polarity-
sensing circuitry. This circuitry protects the battery
charger and the battery from being damaged if they
are improperly connected. If the battery state-of-
charge is too low for the polarity-sensing circuitry to
detect, the battery charger will not operate. This
makes it appear that the battery will not acceptcharging current. See the instructions provided by
the manufacturer of the battery charger for details
on how to bypass the polarity-sensing circuitry.
After the battery has been charged to 12.4 volts or
greater, perform a load test to determine the battery
cranking capacity. Refer to Standard Procedures for
the proper battery load test procedures. If the battery
will endure a load test, return the battery to service.
If the battery will not endure a load test, it is faulty
and must be replaced.
Clean and inspect the battery hold downs, tray,
terminals, posts, and top before completing battery
service. Refer to Battery System Cleaning for the
proper battery system cleaning procedures, and Bat-
tery System Inspection for the proper battery system
inspection procedures.
CHARGING A COMPLETELY DISCHARGED
BATTERY
The following procedure should be used to recharge
a completely discharged battery. Unless this proce-
dure is properly followed, a good battery may be
needlessly replaced.
(1) Measure the voltage at the battery posts with a
voltmeter, accurate to 1/10 (0.10) volt (Fig. 6). If the
reading is below ten volts, the battery charging cur-
rent will be low. It could take some time before the
battery accepts a current greater than a few milliam-
peres. Such low current may not be detectable on the
ammeters built into many battery chargers.
(2) Disconnect and isolate the battery negative
cable. Connect the battery charger leads. Some bat-
tery chargers are equipped with polarity-sensing cir-
cuitry. This circuitry protects the battery charger and
the battery from being damaged if they are improp-
erly connected. If the battery state-of-charge is too
low for the polarity-sensing circuitry to detect, the
battery charger will not operate. This makes it
appear that the battery will not accept charging cur-
rent. See the instructions provided by the manufac-
Fig. 6 Voltmeter - Typical
KJBATTERY SYSTEM 8F - 9
BATTERY (Continued)

CHARGING SYSTEM
TABLE OF CONTENTS
page page
CHARGING SYSTEM
DESCRIPTION.........................22
OPERATION...........................22
DIAGNOSIS AND TESTING - CHARGING
SYSTEM............................22
SPECIFICATIONS
TORQUE - EXCEPT DIESEL.............23
GENERATOR RATINGS - GAS ENGINES . . . 23
SPECIAL TOOLS.......................24
BATTERY TEMPERATURE SENSOR
DESCRIPTION.........................24
OPERATION...........................24
REMOVAL.............................24
INSTALLATION.........................24
GENERATOR
DESCRIPTION.........................25OPERATION...........................25
REMOVAL.............................25
INSTALLATION.........................26
GENERATOR DECOUPLER PULLEY
DESCRIPTION.........................26
OPERATION...........................27
DIAGNOSIS AND TESTING - GENERATOR
DECOUPLER.........................27
REMOVAL.............................27
INSTALLATION.........................30
VOLTAGE REGULATOR
DESCRIPTION.........................31
OPERATION...........................31
CHARGING SYSTEM
DESCRIPTION
The charging system consists of:
²Generator
²Electronic Voltage Regulator (EVR) circuitry
within the Powertrain Control Module (PCM)
²Ignition switch
²Battery (refer to 8, Battery for information)
²Battery temperature sensor
²Generator Lamp (if equipped)
²Check Gauges Lamp (if equipped)
²Wiring harness and connections (refer to 8, Wir-
ing for information)
OPERATION
The charging system is turned on and off with the
ignition switch. The system is on when the engine is
running and the ASD relay is energized. When the
ASD relay is on, voltage is supplied to the ASD relay
sense circuit at the PCM. This voltage is connected
through the PCM and supplied to one of the genera-
tor field terminals (Gen. Source +) at the back of the
generator.
The amount of DC current produced by the gener-
ator is controlled by the EVR (field control) circuitry
contained within the PCM. This circuitry is con-
nected in series with the second rotor field terminal
and ground.
A battery temperature sensor, located in the bat-
tery tray housing, is used to sense battery tempera-ture. This temperature data, along with data from
monitored line voltage, is used by the PCM to vary
the battery charging rate. This is done by cycling the
ground path to control the strength of the rotor mag-
netic field. The PCM then compensates and regulates
generator current output accordingly.
All vehicles are equipped with On-Board Diagnos-
tics (OBD). All OBD-sensed systems, including EVR
(field control) circuitry, are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trou-
ble Code (DTC). The PCM will store a DTC in elec-
tronic memory for certain failures it detects. Refer to
Diagnostic Trouble Codes in; Powertrain Control
Module; Electronic Control Modules for more DTC
information.
The Check Gauges Lamp (if equipped) monitors:
charging system voltage,engine coolant tempera-
ture and engine oil pressure. If an extreme condition
is indicated, the lamp will be illuminated. This is
done as reminder to check the three gauges. The sig-
nal to activate the lamp is sent via the CCD bus cir-
cuits. The lamp is located on the instrument panel.
Refer to 8, Instrument Cluster for additional infor-
mation.
DIAGNOSIS AND TESTING - CHARGING
SYSTEM
The following procedures may be used to diagnose
the charging system if:
²the check gauges lamp (if equipped) is illumi-
nated with the engine running
8F - 22 CHARGING SYSTEMKJ