CHARGING SYSTEM
CONTENTS
page page
GENERAL INFORMATION
OVERVIEW ............................ 1
DESCRIPTION AND OPERATION
BATTERY TEMPERATURE SENSOR ......... 2
CHARGING SYSTEM OPERATION .......... 1
ELECTRONIC VOLTAGE REGULATOR ....... 2
GENERATOR ........................... 2
DIAGNOSIS AND TESTING
BATTERY TEMPERATURE SENSOR ........ 10
CHARGING SYSTEM RESISTANCE TESTS .... 7
CHARGING SYSTEM ..................... 2
CURRENT OUTPUT TEST ................. 8
ON-BOARD DIAGNOSTIC SYSTEM TEST .... 10
REMOVAL AND INSTALLATION
BATTERY TEMPERATURE SENSOR ........ 12
GENERATOR .......................... 11
SPECIFICATIONS
GENERATOR RATINGS .................. 13
TORQUE SPECIFICATIONS ............... 13
GENERAL INFORMATION
OVERVIEW
The battery, starting, and charging systems operate with one another, and must be tested as a complete system. In order for the vehicle to start and
charge properly, all of the components involved in
these systems must perform within specifications.
Group 8A covers the battery, Group 8B covers the
starting system, and Group 8C covers the charging
system. Refer to Group 8W - Wiring Diagrams for
complete circuit descriptions and diagrams. We have
separated these systems to make it easier to locate
the information you are seeking within this Service
Manual. However, when attempting to diagnose any
of these systems, it is important that you keep their
interdependency in mind.
The diagnostic procedures used in these groups
include the most basic conventional diagnostic methods to the more sophisticated On-Board Diagnostics
(OBD) built into the Powertrain Control Module
(PCM). Use of an induction ammeter, volt/ohmmeter,
battery charger, carbon pile rheostat (load tester),
and 12-volt test lamp may be required.
All OBD-sensed systems are monitored by the
PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in
electronic memory for any failure it detects. See the
On-Board Diagnostics Test in Group 8C - Charging
System for more information.
DESCRIPTION AND OPERATION
CHARGING SYSTEM OPERATION
The charging system consists of:
• Generator
• Electronic Voltage Regulator (EVR) circuitry
within the Powertrain Control Module (PCM)
• Ignition switch (refer to Group 8D, Ignition Sys-
tem for information)
• Battery (refer to Group 8A, Battery for informa-
tion)
• Battery temperature sensor
• Voltmeter (refer to Group 8E, Instrument Panel
and Gauges for information)
• Wiring harness and connections (refer to Group
8W, Wiring for information)
The charging system is turned on and off with the
ignition switch. When the ignition switch is turned to
the ON position, battery voltage is applied to the
generator rotor through one of the two field terminals to produce a magnetic field. The generator is
driven by the engine through a serpentine belt and
pulley arrangement.
The amount of DC current produced by the generator is controlled by the EVR (field control) circuitry,
contained within the PCM. This circuitry is connected in series with the second rotor field terminal
and ground.
A battery temperature sensor located on the front
bumper beam is used to sense battery temperature.
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 magnetic field. The PCM then compensates and regulates
generator current output accordingly and to maintain
PL CHARGING SYSTEM 8C - 1
the proper voltage depending on battery temperature.
All vehicles are equipped with On-Board Diagnostics (OBD). All OBD-sensed systems, including the
EVR (field control) circuitry, are monitored by the
PCM. Each monitored circuit is assigned a Diagnostic Trouble Code (DTC). The PCM will store a DTC in
electronic memory for any failure it detects. See OnBoard Diagnostic System Test in this group for more
information.
GENERATOR
The generator is belt-driven by the engine. It is
serviced only as a complete assembly. If the generator fails for any reason, the entire assembly must be
replaced.
As the energized rotor begins to rotate within the
generator, the spinning magnetic field induces a current 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 Y type 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, and ground terminals.
Noise emitting from the generator may be caused
by:
• Worn, loose or defective bearings
• Loose or defective drive pulley
• Incorrect, worn, damaged or misadjusted drive
belt
• Loose mounting bolts
• Misaligned drive pulley
• Defective stator or diode
BATTERY TEMPERATURE SENSOR
The battery temperature sensor is used to determine the battery temperature. This temperature
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 sensor is located forward of the vehicle battery,
and is attached to the battery tray (Fig. 1).
ELECTRONIC VOLTAGE REGULATOR
The Electronic Voltage Regulator (EVR) is not a
separate component. It is actually a voltage regulating 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 generator is controlled by EVR circuitry contained within the 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. The
EVR circuitry monitors system line voltage and battery temperature (refer to Battery Temperature Sensor for more information). It then compensates and
regulates generator current output accordingly. Also
see Charging System Operation for additional information.
DIAGNOSIS AND TESTING
CHARGING SYSTEM
When the ignition switch is turned to the ON position, battery potential will register on the voltmeter.
During engine cranking a lower voltage will appear
on the meter. With the engine running, a voltage
reading higher than the first reading (ignition in ON)
should register.
The following are possible symptoms of a charging
system fault:
• The voltmeter does not operate properly
• An undercharged or overcharged battery condi-
tion occurs.
Remember that an undercharged battery is often
caused by:
• Accessories being left on with the engine not
running
• A faulty or improperly adjusted switch that
allows a lamp to stay on. See Ignition-Off Draw Test
in Group 8A, Battery for more information.
Fig. 1 Battery Temperature Sensor
BATTERY TRAYBATTERY TEMPERATURESENSORAIR INLETTUBE
8C - 2 CHARGING SYSTEM PL
DESCRIPTION AND OPERATION (Continued)
The following procedures may be used to correct a
problem diagnosed as a charging system fault.
INSPECTION
(1) Inspect condition of battery cable terminals,
battery posts, connections at engine block, starter
solenoid and relay. They should be clean and tight.
Repair as required.
(2) Inspect all fuses in the fuseblock module and
Power Distribution Center (PDC) for tightness in
receptacles. They should be properly installed and
tight. Repair or replace as required.
(3) Inspect the electrolyte level in the battery.
Replace battery if electrolyte level is low.
(4) Inspect generator mounting bolts for tightness.
Replace or tighten bolts if required. Refer to the Gen-
erator Removal/Installation section of this group for
torque specifications.
(5) Inspect generator drive belt condition and tension. Tighten or replace belt as required. Refer to
Belt Tension Specifications in Group 7, Cooling System.
(6) Inspect automatic belt tensioner (if equipped).
Refer to Group 7, Cooling System for information.
(7) Inspect connections at generator field, battery
output, and ground terminals. Also check ground connection at engine. They should all be clean and tight.
Repair as required.
PL CHARGING SYSTEM 8C - 3
DIAGNOSIS AND TESTING (Continued)
Charging System Schematic—Typical
8C - 4 CHARGING SYSTEM PL
DIAGNOSIS AND TESTING (Continued)
Charging System Test
CHECK BATTERY CONDI-TION. CHARGE BATTERY IFNECESSARY.CHECK DRIVE BELT. REFERTO GROUP 7, COOLINGSYSTEM FOR ACCESSORYDRIVE BELTS.CHARGING SYSTEM RESIS-TANCE TESTIS GROUND PATH VOLTAGEDROP ABOVE 0.3 VOLTS?YESCLEAN MOUNTING SUR-FACESTIGHTEN FASTENERS TOSPECIFIED TORQUE.NOCHECK ON BOARD DIAG-NOSTIC TROUBLE CODES(DTC).PERFORM OUTPUT VOLT-AGE TESTYESLOW OR NO CHARGINGVOLTAGE OR DTC 41 OR47?NOREFER TO VOLTAGE DROPTEST.NOCHARGING SYSTEM ANDGENERATOR IS OK.CHARGING VOLTAGEABOVE MAXIMUM OR DTC41 OR 46? REFER TO LOADTEST VOLTAGE.YESREFER TO OVERCHARGETEST.
PL CHARGING SYSTEM 8C - 5
DIAGNOSIS AND TESTING (Continued)
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