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8C - 2
CHARGING SYSTEM
DESCRIPTION AND OPERATION (Continued)
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 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 deter-
mine 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.
ELECTRONIC VOLTAGE REGULATOR
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 generator is controlled by EVR circuitry con-
tained 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 bat-
tery temperature (refer to Battery Temperature Sen-
sor for more information). It then compensates and
regulates generator current output accordingly. Also
see Charging System Operation for additional infor-
mation.
DIAGNOSIS AND TESTING
CHARGING SYSTEM
When the ignition switch is turned to the ON posi-
tion, 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.
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 ten-
sion. Tighten or replace belt as required. Refer to
Belt Tension Specifications in Group 7, Cooling Sys-
tem.
(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 con-
nection at engine. They should all be clean and tight.
Repair as required.
JA
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