2003 FORD MUSTANG Workshop Manual

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FORD MUSTANG 2003 Workshop Manual SPECIFICATIONS
SECTION 414-
00: Charging System — General Information 2003 Mustang Workshop Manual General Specifications
Item Specification
Generator
4.6L, Cobra 120 amps @ 6,000 pulley rpm

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FORD MUSTANG 2003 Workshop Manual DESCRIPTION AND OPERATION
Charging System
The charging system is a negative ground system consisting of the following:
�zgenerator
�z internal voltage regulator
�z charging system warning indicat

DESCRIPTION AND OPERATION
Charging System
The charging system is a negative ground system consisting of the following:
zgenerator
z internal voltage regulator
z charging system warning indicator
z storage battery
z necessary wiring and cables
The generator is belt- driven by the engine accessory drive system.
With the ignition key in the run position, voltage is applied through the warning indicator I circuit to the
voltage regulator. This turns the regulator on, allowing current to flow from battery sense A circuit to
the generator field coil. When the engine is started, the generator begins to generate alternating
current (AC) which is converted to direct current (DC) internally. This current is then supplied to the
vehicle's electrical system through the output terminal (B+) of the generator.
Once the generator begins generating current, a voltage signal is taken from the generator stator and
fed back to the internal regulator. This voltage feedback signal (typically half the battery voltage) is
used to turn off the warning indicator.
With the system functioning normally, the generator output current is determined by the voltage of the
A circuit. This A circuit voltage (battery sense circuit) is compared to a set voltage internal to the
regulator, and the regulator controls the generator field current to maintain the correct generator
output.
The set voltage will vary with temperature and is typically higher in cold temperatures than in warm
temperatures. This allows for better battery recharge in the winter and reduces the chance of
overcharging in the summer.
The battery is a 12 volt direct current source connected in a negative ground system. The battery case
is sealed and includes two vent holes to release gases. The battery has three major functions:
zengine cranking power source
z voltage stabilizer for the electrical system
z temporary power when electrical loads exceed the generator output current
Circuit Description
Battery Output Terminal (B+)
The generator output is supplied through the battery positive output (B+) terminal on the back of the
generator to the battery and electrical system.
I Circuit 904 (LG/RD)
The I (ignition) circuit is used to turn on the voltage regulator. This circuit is powered up with the
ignition key in the run position. This circuit is also used to turn the charging system warning indicator
on if there is a fault in the charging system operation. SECTION 414-
00: Charging System — General Information 2003 Mustang Workshop Manual Klj . 1 ba
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FORD MUSTANG 2003 Workshop Manual A Circuit 36 (YE/WH)
The A circuit or battery sense circuit is used to sense battery voltage. This voltage is used by the
regulator to determine generator output. This circuit is also used to supply

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FORD MUSTANG 2003 Workshop Manual DIAGNOSIS AND TESTING
Charging System
Refer to Wiring Diagrams Cell
12 , Charging System for schematic and connector information.
Principles of Operation SECTION 414-
00: Charging System — Gen

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FORD MUSTANG 2003 Workshop Manual Functionality
With the ignition switch in the RUN position, voltage is applied through the warning indicator I circuit
904 (LG/RD) to the voltage regulator. This turns the regulator on, allowing cur

Functionality
With the ignition switch in the RUN position, voltage is applied through the warning indicator I circuit
904 (LG/RD) to the voltage regulator. This turns the regulator on, allowing current to flow from battery
sense A circuit 36 (YE/WH) to the generator field coil. When the engine is started, the generator
begins to generate alternating current (AC) which is internally converted to direct current (DC). This
current is then supplied to the vehicle's electrical system through the output (B+) terminal of the
generator.
Once the generator begins generating current, a voltage signal is taken from the generator stator and
fed back to the regulator internally. This voltage feedback signal (typically half the battery voltage) is
used to turn off the warning indicator.
With the system functioning normally, the generator output current is determined by the voltage of the
A circuit. The A circuit voltage is compared to a set voltage internal to the regulator, and the regulator
controls the generator field current to maintain the correct generator output.
The set voltage will vary with temperature and is typically higher in cold temperatures and lower in
warm temperatures. This allows for better battery recharge in the winter and reduces the chance of
overcharging in the summer.
Battery Positive Output Circuit 38 (B+) (BK/OG)
The generator output is supplied through the battery positive output (B+) terminal on the back of the
generator to the battery and electrical system.
I Circuit 904 (LG/RD)
The I (ignition) circuit is used to turn on the voltage regulator. This circuit is powered up with the
ignition key in the run position. This circuit is also used to turn the charging system warning indicator
on if there is a fault in the charging system operation.
A Circuit 36 (YE/WH)
The A circuit or battery sense circuit is used to sense battery voltage. This voltage is used by the
regulator to determine generator output. This circuit is used to supply current to the generator field
(rotor). The amount of current supplied to the rotor will determine generator output.
Inspection and Verification
WARNING: Batteries contain sulfuric acid. Avoid contact with skin, eyes, or clothing.
Also, shield your eyes when working near batteries to protect against possible splashing of the
acid solution. In case of acid contact with skin or eyes, flush immediately with water for a
minimum of 15 minutes and get prompt medical attention. If acid is swallowed, call a physician
immediately.
WARNING: Batteries normally produce explosive gases which can cause personal injury.
Therefore, do not allow flames, sparks or lighted substances to come near the battery. When
charging or working near a battery, always shield your face and protect your eyes. Always Connector C102a End View
A Circuit 36 (YE/WH)
I Circuit 904 (LG/RD) Klj . 2 ba
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FORD MUSTANG 2003 Workshop Manual provide ventilation.
WARNING: When lifting a plastic- cased battery, excessive pressure on the end walls
could cause acid to spew through the vent caps resulting in personal injury, damage to the

provide ventilation.
WARNING: When lifting a plastic- cased battery, excessive pressure on the end walls
could cause acid to spew through the vent caps resulting in personal injury, damage to the
vehicle or to the battery. Lift with a battery carrier or with your hands on opposite corners.
1. Verify the customer concern by operating the engine to duplicate the concern.
2. Inspect the charging system (battery, generator cable, harness connectors, connections) to determine if any obvious mechanical or electrical concerns exist. If found, repair as necessary
and test the system for normal operation. Refer to the following tables:
3. Check the operation of the charging system warning indicator lamp (instrument cluster). Normal operation is as follows:
zWith the ignition switch OFF, the charging system warning indicator should be OFF.
z With the ignition switch in RUN and the engine off, the charging system warning indicator
light should be on.
z With the engine running, the charging system warning indicator light should be off.
4. Verify the battery is being charged. Carry out the Battery— Load Test. Refer to Component
Tests in this section.
5. If the customer concern is verified after the initial inspection, refer to the Symptom Chart to determine which tests to carry out.
Symptom Chart Visual Inspection Chart
Mechanical Electrical
z
Battery case, posts, hold- down clamp, cables and
connections
z Generator drive (serpentine) belt for condition and
tension. Refer to Section 303 - 05 .
z Generator pulley z
Battery junction box (BJB)
fuse 20 (20A)
z Fuse links
z Circuitry
z Battery charge warning
indicator
z Cables
Normal Charging System Voltages Ignition
Switch
Position A Circuit
36
(YE/WH) I Circuit
904
(LG/RD) Generator B+
Circuit 38 (BK/OG) Battery Engine to
battery
ground Charging
System Warning Indicator
Operation OFF 12V 0V 12V 12V 0V Off
RUN-
engine off 12V 1-
3V 12V 12V 0V Illuminated
RUN-
engine
running 13-
15V 13-
15V 13-
15V 13-15V 0V Off Klj . 3 ba
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FORD MUSTANG 2003 Workshop Manual Pinpoint Tests
CAUTION: Do not make jumper connections except as directed. Incorrect connections
may damage the voltage regulator test terminals, fuses, or fuse links.
CAUTION: Do not allow any m

Pinpoint Tests
CAUTION: Do not make jumper connections except as directed. Incorrect connections
may damage the voltage regulator test terminals, fuses, or fuse links.
CAUTION: Do not allow any metal object to come in contact with the generator housing
and internal diode cooling fins.
NOTE: All voltage measurements are referenced to the negative (- ) battery post unless otherwise
specified. PINPOINT TEST A: BATTERY IS DISCHARGED OR VOLTAGE IS Symptom Chart
Condition
Possible Sources Action
z Battery is discharged or voltage is
low z
Circuitry.
z High key- off current
drain(s).
z Battery.
z Generator. z
Go To Pinpoint
Test A .
z The charging system warning
indicator is on with the engine
running (the system voltage does
not increase) z
Circuitry.
z Voltage regulator.
z Generator. z
Go To Pinpoint
Test B .
z The system overcharges (the
battery voltage is greater than 15.5
volts) z
Circuitry.
z Voltage regulator.
z Generator. z
Go To Pinpoint
Test C .
z The charging system warning
indicator is on with the engine
running and the battery increases
voltage z
Circuitry.
z Instrument cluster.
z Voltage regulator.
z Generator. z
Go To Pinpoint
Test D .
z The charging system warning
indicator is off with the ignition
switch in the RUN position and the
engine off z
Bulb.
z Circuitry.
z Instrument cluster.
z Voltage regulator.
z Generator. z
Go To Pinpoint
Test E .
z The charging system warning
indicator flickers or is intermittent z
Central junction box
(CJB) fuse 5 (15A).
z Generator
connector
unplugged (C102a).
z Circuitry.
z Generator. z
Go To Pinpoint
Test F .
z The generator is noisy zBolts or brackets.
z Drive belt.
z Generator or pulley. z
Go To Pinpoint
Test G .
z Radio interference zGenerator.
z Circuitry.
z In-vehicle
entertainment
system. z
Go To Pinpoint
Test F . Klj . 4 ba
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FORD MUSTANG 2003 Workshop Manual LOW
PINPOINT TEST B: THE CHARGING SYSTEM WARNING INDICATOR
IS ON WITH THE ENGINE RUNNING (THE BATTERY VOLTAGE
DOES NOT INCREASE)
Test Step Result / Action to Take
A1 CHECK BATTERY CONDITION
�z

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