2004 CHRYSLER VOYAGER Power system

²Battery Holddown- The battery holddown
hardware secures the battery in the battery tray in
the engine compartment.
²Battery Thermowrap- The battery thermow-
rap insulates the battery to protect it from engine
compartment temperature extremes.
²Battery Tray- The battery tray provides a
secure mounting location in the vehicle for the bat-
tery and an anchor point for the battery holddown
hardware.
For battery system maintenance schedules and
jump starting procedure, see the owner's manual in
the vehicle glove box. Optionally, refer to the Lubri-
cation and Maintenance section of this manual for
the recommended battery maintenance schedules and
for the proper battery jump starting procedure. While
battery charging can be considered a maintenance
procedure, the battery charging procedure and
related information are located later in this section of
this service manual. This was done because the bat-
tery must be fully-charged before any battery system
diagnosis or testing procedures can be performed.
OPERATION
The battery system is designed to provide a safe,
efficient, reliable and mobile means of delivering and
storing electrical energy. This electrical energy is
required to operate the engine starting system, as
well as to operate many of the other vehicle acces-
sory systems for limited durations while the engine
and/or the charging system are not operating. The
battery system is also designed to provide a reserve
of electrical energy to supplement the charging sys-
tem for short durations while the engine is running
and the electrical current demands of the vehicle
exceed the output of the charging system. In addition
to delivering, and storing electrical energy for the
vehicle, the battery system serves as a capacitor and
voltage stabilizer for the vehicle electrical system. It
absorbs most abnormal or transient voltages caused
by the switching of any of the electrical components
or circuits in the vehicle.
DIAGNOSIS AND TESTING - BATTERY SYSTEM
The battery, starting, and charging systems in the
vehicle operate with one another and must be tested
as a complete system. In order for the engine to start
and the battery to maintain its charge properly, all of
the components that are used in these systems must
perform within specifications. It is important that
the battery, starting, and charging systems be thor-
oughly tested and inspected any time a battery needs
to be charged or replaced. The cause of abnormal bat-
tery discharge, overcharging or early battery failure
must be diagnosed and corrected before a battery is
replaced and before a vehicle is returned to service.
The service information for these systems has been
separated within this service manual to make it eas-
ier to locate the specific information you are seeking.
However, when attempting to diagnose any of these
systems, it is important that you keep their interde-
pendency in mind.
The diagnostic procedures used for the battery,
starting, and charging systems 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-type milliampere ammeter, a volt/ohmme-
ter, a battery charger, a carbon pile rheostat (load
tester) and a 12-volt test lamp may be required. All
OBD-sensed systems 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 any failure it detects. Refer to
Charging System for the proper charging system on-
board diagnostic test procedures.
MICRO 420 BATTERY TESTER
The Micro 420 automotive battery system tester is
designed to help the dealership technicians diagnose
the cause of a defective battery. Follow the instruc-
tion manual supplied with the tester to properly
diagnose a vehicle. If the instruction manual is not
available refer to the standard procedure in this sec-
tion, which includes the directions for using the
Micro 420 battery tester.
8F - 2 BATTERY SYSTEMRS
BATTERY SYSTEM (Continued)

SPECIAL TOOLS
BATTERY SYSTEM SPECIAL TOOLS
BATTERY
DESCRIPTION
There are three different batteries available on this
model. Vehicles equipped with a diesel engine utilize
a spiral wound plate designed battery with recombi-
nation technology. This is a maintenance-free battery
that is capable of delivering more power than a con-
ventional battery. This additional power is required
by a diesel engine during cold cranking. Vehicles
equipped with a gasoline engine utilize a conven-
tional battery. Refer to the following information for
detailed differences and descriptions of these batter-
ies.
SPIRAL PLATE BATTERY - DIESEL ENGINE
Spiral plate technology takes the elements of tradi-
tional batteries - lead and sulfuric acid - to the next
level. By tightly winding layers of spiral grids and
acid-permeated vitreous separators into cells, the
manufacturer has developed a battery with more
power and service life than conventional batteries the
same size. The spiral plate battery is completely, per-
manently sealed. Through gas recombination, hydro-
gen and oxygen within the battery are captured
during normal charging and reunited to form the
water within the electrolyte, eliminating the need to
add distilled water. Therefore, these batteries havenon-removable battery vent caps (Fig. 4). Watercan-
notbe added to this battery.
The acid inside a spiral plate battery is bound
within the vitreous separators, ending the threat of
acid leaks. This feature allows the battery to be
installed in any position anywhere in the vehicle.
Spiral plate technology is the process by which the
plates holding the active material in the battery are
wound tightly in coils instead of hanging flat, like
conventional batteries. This design has a lower inter-
nal resistance and also increases the active material
surface area.
WARNING: NEVER EXCEED 14.4 VOLTS WHEN
CHARGING A SPIRAL PLATE BATTERY. PERSONAL
INJURY AND/OR BATTERY DAMAGE MAY RESULT.
Due to the maintanance-free design, distilled water
cannot be added to this battery. Therefore, if more
than 14.4 volts are used during the spiral plate bat-
tery charging process, water vapor can be exhausted
through the pressure-sensitive battery vents and lost
for good. This can permanently damage the spiral
plate battery. Never exceed 14.4 volts when charging
a spiral plate battery. Personal injury and/or battery
damage may result.
CONVENTIONAL BATTERY - GASOLINE ENGINE
Low-maintenance batteriesare used on export
vehicles equipped with a gasoline engine, these bat-
teries have removable battery cell caps (Fig. 5).
Watercanbe added to this battery. Under normal
MICRO 420 BATTERY TESTER
Fig. 4 MAINTENANCE-FREE DIESEL ENGINE
BATTERY
RSBATTERY SYSTEM8F-7
BATTERY SYSTEM (Continued)

CONVENTIONAL BATTERY CHARGING TIME TABLE
Charging
Amperage5 Amps10
Amps20 Amps
Open Circuit
VoltageHours Charging @ 21É C
(70É F)
12.25 to 12.49 6 hours 3 hours 1.5
hours
12.00 to 12.24 10 hours 5 hours 2.5
hours
10.00 to 11.99 14 hours 7 hours 3.5
hours
Below 10.00 18 hours 9 hours 4.5
hours
STANDARD PROCEDURE - OPEN-CIRCUIT
VOLTAGE TEST
A battery open-circuit voltage (no load) test will
show the approximate state-of-charge of a battery.
This test can be used if no other battery tester is
available.
Before proceeding with this test, completely charge
the battery. Refer to Standard Procedures for the
proper battery charging procedures.
(1) Before measuring the open-circuit voltage, the
surface charge must be removed from the battery.
Turn on the headlamps for fifteen seconds, then
allow up to five minutes for the battery voltage to
stabilize.
(2) Disconnect and isolate both battery cables, neg-
ative cable first.
(3) Using a voltmeter connected to the battery
posts (see the instructions provided by the manufac-
turer of the voltmeter), measure the open-circuit volt-
age (Fig. 9).
See the Open-Circuit Voltage Table. This voltage
reading will indicate the battery state-of-charge, but
will not reveal its cranking capacity. If a battery has
an open-circuit voltage reading of 12.4 volts orgreater, it may be load tested to reveal its cranking
capacity. Refer to Standard Procedures for the proper
battery load test procedures.
OPEN CIRCUIT VOLTAGE TABLE
Open Circuit Voltage Charge Percentage
11.7 volts or less 0%
12.0 volts 25%
12.2 volts 50%
12.45 volts 75%
12.65 volts or more 100%
STANDARD PROCEDURE - IGNITION-OFF
DRAW TEST
The term Ignition-Off Draw (IOD) identifies a nor-
mal condition where power is being drained from the
battery with the ignition switch in the Off position. A
normal vehicle electrical system will draw from fif-
teen to twenty-five milliamperes (0.015 to 0.025
ampere) with the ignition switch in the Off position,
and all non-ignition controlled circuits in proper
working order. Up to twenty-five milliamperes are
needed to enable the memory functions for the Pow-
ertrain Control Module (PCM), digital clock, electron-
ically tuned radio, and other modules which may
vary with the vehicle equipment.
A vehicle that has not been operated for approxi-
mately twenty-one days, may discharge the battery
to an inadequate level. When a vehicle will not be
used for twenty-one days or more (stored), remove
the IOD fuse from the Integrated Power Module
(IPM). This will reduce battery discharging.
Excessive IOD can be caused by:
²Electrical items left on.
²Faulty or improperly adjusted switches.
²Faulty or shorted electronic modules and compo-
nents.
²An internally shorted generator.
²Intermittent shorts in the wiring.
If the IOD is over twenty-five milliamperes, the
problem must be found and corrected before replac-
ing a battery. In most cases, the battery can be
charged and returned to service after the excessive
IOD condition has been corrected.
(1) Verify that all electrical accessories are off.
Turn off all lamps, remove the ignition key, and close
all doors. If the vehicle is equipped with an illumi-
nated entry system or an electronically tuned radio,
allow the electronic timer function of these systems
to automatically shut off (time out). This may take
up to twenty minutes.
(2) Disconnect the battery negative cable.
(3) Set an electronic digital multi-meter to its
highest amperage scale. Connect the multi-meter
Fig. 9 Testing Open-Circuit Voltage - Typical
RSBATTERY SYSTEM8F-13
BATTERY (Continued)

between the disconnected battery negative cable ter-
minal clamp and the battery negative terminal post.
Make sure that the doors remain closed so that the
illuminated entry system is not activated. The multi-
meter amperage reading may remain high for up to
three minutes, or may not give any reading at all
while set in the highest amperage scale, depending
upon the electrical equipment in the vehicle. The
multi-meter leads must be securely clamped to the
battery negative cable terminal clamp and the bat-
tery negative terminal post. If continuity between the
battery negative terminal post and the negative cable
terminal clamp is lost during any part of the IOD
test, the electronic timer function will be activated
and all of the tests will have to be repeated.
(4) After about three minutes, the high-amperage
IOD reading on the multi-meter should become very
low or nonexistent, depending upon the electrical
equipment in the vehicle. If the amperage reading
remains high, remove and replace each fuse or circuit
breaker in the Integrated Power Module (IPM), one
at a time until the amperage reading becomes very
low, or nonexistent. Refer to the appropriate wiring
information in this service manual for complete Inte-
grated Power Module fuse, circuit breaker, and cir-
cuit identification. This will isolate each circuit and
identify the circuit that is the source of the high-am-
perage IOD. If the amperage reading remains high
after removing and replacing each fuse and circuit
breaker, disconnect the wire harness from the gener-
ator. If the amperage reading now becomes very low
or nonexistent, refer to Charging System for the
proper charging system diagnosis and testing proce-
dures. After the high-amperage IOD has been cor-
rected, switch the multi-meter to progressively lower
amperage scales and, if necessary, repeat the fuse
and circuit breaker remove-and-replace process to
identify and correct all sources of excessive IOD. It is
now safe to select the lowest milliampere scale of the
multi-meter to check the low-amperage IOD.
CAUTION: Do not open any doors, or turn on any
electrical accessories with the lowest milliampere
scale selected, or the multi-meter may be damaged.
(5) Allow twenty minutes for the IOD to stabilize
and observe the multi-meter reading. The low-amper-
age IOD should not exceed twenty-five milliamperes
(0.025 ampere). If the current draw exceeds twenty-
five milliamperes, isolate each circuit using the fuse
and circuit breaker remove-and-replace process in
Step 4. The multi-meter reading will drop to within
the acceptable limit when the source of the excessive
current draw is disconnected. Repair this circuit as
required; whether a wiring short, incorrect switch
adjustment, or a component failure is at fault.STANDARD PROCEDURE - CHECKING BATTERY
ELECTROLYTE LEVEL
The following procedure can be used to check the
electrolyte level in a low-maintenance lead-acid bat-
tery.
(1) Unscrew and remove the battery cell caps with
a flat-bladed screw driver (Fig. 10).
WARNING: NEVER PUT YOUR FACE NEAR A GAS-
SING, HOT OR SWELLED BATTERY. SERIOUS PER-
SONAL INJURY MAY RESULT.
(2) Wearing safety glasses, look through the bat-
tery cell cap holes to determine the level of the elec-
trolyte in the battery. The electrolyte should be above
the hooks inside the battery cells (Fig. 11).
(3)Add only distilled wateruntil the electrolyte
is above the hooks inside the battery cells (Fig. 11).
Fig. 10 BATTERY CELL CAP REMOVAL/
INSTALLATION - LOW-MAINTENANCE BATTERY
ONLY
1 - BATTERY CELL CAP
2 - BATTERY CASE
8F - 14 BATTERY SYSTEMRS
BATTERY (Continued)

REMOVAL - BATTERY
WARNING: A SUITABLE PAIR OF HEAVY DUTY
RUBBER GLOVES AND SAFETY GLASSES SHOULD
BE WORN WHEN REMOVING OR SERVICING A
BATTERY.
WARNING: REMOVE METALLIC JEWELRY TO
AVOID INJURY BY ACCIDENTAL ARCING OF BAT-
TERY CURRENT.
(1) Verify that the ignition switch and all accesso-
ries are OFF.
(2) Disconnect the battery cables from the battery
posts, negative first (Fig. 12).
(3) Remove the battery hold down retaining nut.
(4) Remove the battery hold down bracket.
(5) Remove the battery from the vehicle.
INSTALLATION
(1) Position the battery in the battery tray.
(2) Install the battery hold down bracket and
retaining nut. Torque the nut to 20 N´m (180 in. lbs.).
(3) Connect the battery cables to the battery posts,
positive cable first. Torque terminal fasteners to 5
N´m (40 in. lbs.).
BATTERY HOLDDOWN
DESCRIPTION
The battery hold down hardware consists of a
molded plastic lip that is integral to the outboard
edge of the battery tray and support unit, a molded
steel hold down bracket and a single hex nut with a
coned washer.
When installing a battery into the battery tray, be
certain that the hold down hardware is properly
installed and that the fasteners are tightened to the
proper specifications. Improper hold down fastener
tightness, whether too loose or too tight, can result in
damage to the battery, the vehicle or both. Refer to
Battery Hold Downsin this section of this service
manual for the location of the proper battery hold
down installation procedures, including the proper
hold down fastener tightness specifications.
OPERATION
The battery holddown secures the battery in the
battery tray. This holddown is designed to prevent
battery movement during the most extreme vehicle
operation conditions. Periodic removal and lubrica-
tion of the battery holddown hardware is recom-
mended to prevent hardware seizure at a later date.
Fig. 11 HOOK INSIDE BATTERY CELLS - LOW-
MAINTENANCE BATTERY ONLY
1 - TOP OF BATTERY
2 - HOOK INSIDE BATTERY CELLS
Fig. 12 BATTERY POSITION & ORIENTATION
1 - BATTERY THERMOWRAP (IF EQUIPPED)
2 - INTEGRATED POWER MODULE
3 - FRONT CONTROL MODULE
RSBATTERY SYSTEM8F-15
BATTERY (Continued)

NOTE: Never operate a vehicle without a battery
holddown device properly installed. Damage to the
vehicle, components and battery could result.
REMOVAL
All of the battery hold down hardware can be ser-
viced without removal of the battery or the battery
tray and support unit.
(1) Turn the ignition switch to the Off position. Be
certain that all electrical accessories are turned off.
(2) Remove the nut with washer that secures the
battery hold down bracket to the battery tray and
support unit.
(3) Remove the battery hold down bracket from
the battery tray and support unit.
INSTALLATION
(1) Install the battery hold down bracket in the
battery tray and support unit.
(2) Install the nut with washer that secures the
battery hold down bracket to the battery tray and
support unit. Torque to 20 N´m (180 in. lbs.).
BATTERY CABLES
DESCRIPTION
The battery cables are large gauge, stranded cop-
per wires sheathed within a heavy plastic or syn-
thetic rubber insulating jacket. The wire used in the
battery cables combines excellent flexibility and reli-
ability with high electrical current carrying capacity.
Refer toWiring Diagramsin the index of this ser-
vice manual for the location of the proper battery
cable wire gauge information.
A clamping type female battery terminal made of
stamped metal is attached to one end of the battery
cable wire. A square headed pinch-bolt and hex nut
are installed at the open end of the female battery
terminal clamp. Large eyelet type terminals are
crimped onto the opposite end of the battery cable
wire and then solder-dipped. The battery positive
cable wires have a red insulating jacket to provide
visual identification and feature a larger female bat-
tery terminal clamp to allow connection to the larger
battery positive terminal post. The battery negative
cable wires have a black insulating jacket and a
smaller female battery terminal clamp.
The battery cables cannot be repaired and, if dam-
aged or faulty they must be replaced. Both the bat-
tery positive and negative cables are available for
service replacement only as a unit with the battery
wire harness, which may include portions of the wir-
ing circuits for the generator and other components
on some models. Refer toWiring Diagramsin theindex of this service manual for the location of more
information on the various wiring circuits included in
the battery wire harness for the vehicle being ser-
viced.
OPERATION
The battery cables connect the battery terminal
posts to the vehicle electrical system. These cables
also provide a path back to the battery for electrical
current generated by the charging system for restor-
ing the voltage potential of the battery. The female
battery terminal clamps on the ends of the battery
cable wires provide a strong and reliable connection
of the battery cable to the battery terminal posts.
The terminal pinch bolts allow the female terminal
clamps to be tightened around the male terminal
posts on the top of the battery. The eyelet terminals
secured to the opposite ends of the battery cable
wires from the female battery terminal clamps pro-
vide secure and reliable connection of the battery
cables to the vehicle electrical system.
The battery positive cable terminal clamp is
attached to the ends of two wires. One wire has an
eyelet terminal that connects the battery positive
cable to the B(+) terminal stud of the Integrated
Power Module (IPM), and the other wire has an eye-
let terminal that connects the battery positive cable
to the B(+) terminal stud of the engine starter motor
solenoid. The battery negative cable terminal clamp
is also attached to the ends of two wires. One wire
has an eyelet terminal that connects the battery neg-
ative cable to the vehicle powertrain through a stud
on the left side of the engine cylinder block. The
other wire has an eyelet terminal that connects the
battery negative cable to the vehicle body through a
ground screw on the left front fender inner shield,
near the battery.
DIAGNOSIS AND TESTING - BATTERY CABLE
A voltage drop test will determine if there is exces-
sive resistance in the battery cable terminal connec-
tions or the battery cable. If excessive resistance is
found in the battery cable connections, the connec-
tion point should be disassembled, cleaned of all cor-
rosion or foreign material, then reassembled.
Following reassembly, check the voltage drop for the
battery cable connection and the battery cable again
to confirm repair.
When performing the voltage drop test, it is impor-
tant to remember that the voltage drop is giving an
indication of the resistance between the two points at
which the voltmeter probes are attached.EXAM-
PLE:When testing the resistance of the battery pos-
itive cable, touch the voltmeter leads to the battery
positive cable terminal clamp and to the battery pos-
itive cable eyelet terminal at the starter solenoid
8F - 16 BATTERY SYSTEMRS
BATTERY HOLDDOWN (Continued)

B(+) terminal stud. If you probe the battery positive
terminal post and the battery positive cable eyelet
terminal at the starter solenoid B(+) terminal stud,
you are reading the combined voltage drop in the
battery positive cable terminal clamp-to-terminal
post connection and the battery positive cable.
VOLTAGE DROP TEST
The following operation will require a voltmeter
accurate to 1/10 (0.10) volt. Before performing this
test, be certain that the following procedures are
accomplished:
²The battery is fully-charged and load tested.
Refer to Standard Procedures for the proper battery
charging and load test procedures.
²Fully engage the parking brake.
²If the vehicle is equipped with an automatic
transmission, place the gearshift selector lever in the
Park position. If the vehicle is equipped with a man-
ual transmission, place the gearshift selector lever in
the Neutral position and block the clutch pedal in the
fully depressed position.
²Verify that all lamps and accessories are turned
off.
²To prevent the engine from starting, remove the
Automatic Shut Down (ASD) relay. The ASD relay is
located in the Intelligent Power Module (IPM), in the
engine compartment. See the fuse and relay layout
label affixed to the underside of the IPM cover for
ASD relay identification and location.
(1) Connect the positive lead of the voltmeter to
the battery negative terminal post. Connect the neg-
ative lead of the voltmeter to the battery negative
cable terminal clamp (Fig. 13). Rotate and hold the
ignition switch in the Start position. Observe the
voltmeter. If voltage is detected, correct the poor con-
nection between the battery negative cable terminal
clamp and the battery negative terminal post.
(2) Connect the positive lead of the voltmeter to
the battery positive terminal post. Connect the nega-
tive lead of the voltmeter to the battery positive cable
terminal clamp (Fig. 14). Rotate and hold the ignition
switch in the Start position. Observe the voltmeter. If
voltage is detected, correct the poor connection
between the battery positive cable terminal clamp
and the battery positive terminal post.
(3) Connect the voltmeter to measure between the
battery positive cable terminal clamp and the starter
solenoid B(+) terminal stud (Fig. 15). Rotate and hold
the ignition switch in the Start position. Observe the
voltmeter. If the reading is above 0.2 volt, clean and
tighten the battery positive cable eyelet terminal con-
nection at the starter solenoid B(+) terminal stud.
Repeat the test. If the reading is still above 0.2 volt,
replace the faulty battery positive cable.(4) Connect the voltmeter to measure between the
battery negative cable terminal clamp and a good
clean ground on the engine block (Fig. 16). Rotate
and hold the ignition switch in the Start position.
Observe the voltmeter. If the reading is above 0.2
volt, clean and tighten the battery negative cable
eyelet terminal connection to the engine block.
Repeat the test. If the reading is still above 0.2 volt,
replace the faulty battery negative cable.
Fig. 13 Testing Battery Negative Connection
Resistance
1 - VOLTMETER
2 - BATTERY
Fig. 14 Testing Battery Positive Connection
Resistance
1 - VOLTMETER
2 - BATTERY
RSBATTERY SYSTEM8F-17
BATTERY CABLES (Continued)

CHARGING
TABLE OF CONTENTS
page page
CHARGING
DESCRIPTION - CHARGING SYSTEM.......20
OPERATION - CHARGING SYSTEM.........20
DIAGNOSIS AND TESTING - ON-BOARD
DIAGNOSTIC SYSTEM.................21
SPECIFICATIONS
GENERATOR........................22
TORQUE............................22
SPECIFICATIONS - BATTERY
TEMPERATURE SENSOR...............22
SPECIAL TOOLS.......................23
BATTERY TEMPERATURE SENSOR
DESCRIPTION.........................23
OPERATION...........................23
REMOVAL.............................23
GENERATOR
DESCRIPTION.........................23OPERATION...........................23
REMOVAL
REMOVAL - 2.4L......................23
REMOVAL - 3.3/3.8L...................24
INSTALLATION
INSTALLATION - 2.4L..................24
INSTALLATION - 3.3/3.8L................24
GENERATOR DECOUPLER PULLEY
DESCRIPTION.........................25
OPERATION...........................25
DIAGNOSIS AND TESTING - GENERATOR
DECOUPLER PULLEY..................25
REMOVAL.............................26
INSTALLATION.........................26
VOLTAGE REGULATOR
DESCRIPTION.........................27
OPERATION...........................27
CHARGING
DESCRIPTION - CHARGING SYSTEM
The charging system consists of:
²Generator
²Decoupler Pulley (If equipped)
²Electronic Voltage Regulator (EVR) circuitry
within the Powertrain Control Module (PCM)
²Ignition switch (refer to the Ignition System sec-
tion for information)
²Battery (refer to the Battery section for informa-
tion)
²Ambient Air Temperature (If equipped)
²Inlet Air Temperature (calculated battery tem-
perature)(If equipped)
²Voltmeter (refer to the Instrument Cluster sec-
tion for information if equipped)
²Wiring harness and connections (refer to the
Wiring section for information)
²Accessory drive belt (refer to the Cooling section
for more information)
²Battery Temperature sensor (if equipped)
OPERATION - CHARGING SYSTEM
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. The ASD
relay is energized when the PCM grounds the ASD
control circuit. (SBEC vehicles) This voltage is con-
nected through the PCM or IPM (intelligent powermodule) (if equipped) and supplied to one of the gen-
erator field terminals (Gen. Source +) at the back of
the generator.
The generator is driven by the engine through a
serpentine belt and pulley or decoupler pulley
arrangement.
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.
(SBEC vehicles) An Inlet air temperature sensor is
used to calculate the temperature near the battery.
This temperature data, along with data from moni-
tored line voltage (battery voltage sense circuit), 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 to maintain system voltage at the tar-
geted system voltage based on battery temperature.
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 and
illuminate the (MIL) lamp. Refer to On-Board Diag-
nostics in the Electronic Control Modules(Refer to 8 -
ELECTRICAL/ELECTRONIC CONTROL MOD-
8F - 20 CHARGINGRS