2003 FORD MUSTANG key battery

PINPOINT TEST B: THE HORN SOUNDS CONTINUOUSLY connector Pin 3, Circuit 6 (component side), and air bag sliding
contact C218a Pin 2, Circuit 6 (component side).
z Is the resistance less than 5 ohms? No
INSTALL a new air
bag sliding contact.
REFER to
Section 501 - 20B . TEST the
system for normal
operation. A7 CHECK THE STEERING WHEEL SWITCH HARNESS
z
Inspect the steering wheel switch harness for chafing, opens or
possible short to ground.
z Is the steering wheel switch harness OK? Yes
INSTALL a new horn
switch. REFER to
Switch
— Horn . TEST
the system for normal
operation.
No
INSTALL a new
steering wheel switch
harness. TEST the
system for normal
operation. Test Step Result / Action to Take
B1 CHECK HORN CIRCUIT 1 (DB)
z
Key in OFF position.
z Disconnect: Horn Relay.
z Does the horn continue to sound? Yes
REPAIR Circuit 1 (DB) for short to battery. TEST
the system for normal operation.
No
GO to
B2 .
B2 CHECK HORN RELAY
z
Check the horn relay; refer to Wiring
Diagrams Cell 149.
z Is the horn relay OK? Yes
REINSTALL the horn relay. GO to
B3 .
No
INSTALL a new horn relay. TEST the system for
normal operation. B3 CHECK CIRCUIT 6 (YE/LG)
z
Disconnect: Air Bag Sliding Contact
C218a .
z Does the horn continue to sound? Yes
GO to
B4 .
No
RECONNECT the air bag sliding contact. GO to
B5 .
B4 CHECK GEM INPUT
z
Disconnect: GEM C201e. Yes Klj . 4 ba
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Pinpoint Tests
CAUTION: Before removing and installing the generic electronic module (GEM) or its
connectors, disconnect the battery. Failure to follow this caution will result in the GEM storing
many erroneous DTCs, and it may exhibit erratic operation after installation.
CAUTION: Be careful when probing the central junction box (CJB), or any connectors.
Damage will result to the connector receptacle if the probe or terminal used is too large.
CAUTION: Electronic modules are sensitive to static discharges. If exposed to these
charges, damage may result.
NOTE: If continuous DTCs are recorded and the symptom is not present when carrying out the
pinpoint tests, an intermittent concern may be the cause. Always check for loose connections and
corroded terminals.
Complete the entire pinpoint test related to the symptom before installing a new GEM.
PINPOINT TEST A: NO COMMUNICATION WITH THE GENERIC
ELECTRONIC MODULE (GEM) Test Step Result / Action to Take
A1 CHECK THE GENERIC ELECTRONIC MODULE (GEM)
POWER SUPPLY z
Key in OFF position.
z Disconnect: Generic Electronic Module (GEM) C201a.
z Disconnect: GEM C201b.
z Key in ON position.
z Using the following table, measure the voltage between the
GEM, harness side and ground.
z Are the voltages greater than 10 volts? Connector Pin Circuit
C201a 4 400 (LB/BK)
C201a 1 1006 (DG/WH)
C201b 2 1001 (WH/YE)
C201b 3 193 (YE/LG) Yes
GO to
A2 .
No
REPAIR the circuit(s) in
question. TEST the system
for normal operation. A2 CHECK THE GEM GROUND CIRCUIT 397 (BK/WH) FOR
OPEN z
Key in OFF position.
z Measure the resistance between the GEM C201b pin 4,
circuit 397 (BK/WH), harness side and ground. Yes
GO to
A3 .
No
REPAIR the circuit(s) in
question. TEST the system
for normal operation. Klj . 5 ba
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PINPOINT TEST F: THE SAFETY BELT WARNING CHIME DOES NOT
OPERATE CORRECTLY z
Is the resistance less than 5 ohms? E8 TEST CIRCUIT 14 (BN) FOR SHORT TO BATTERY
z
Key in OFF position.
z Disconnect: GEM C201c.
z Set the headlamp switch in the OFF position. Measure the
voltage between GEM C201c pin 7, circuit 14 (BN),
harness side and ground.
z Is the voltage greater than 10 volts? Yes
REPAIR the circuit. REPEAT
the self-
test. CLEAR the
DTCs.
No
GO to E9 .
E9 CHECK FOR CORRECT MODULE OPERATION
z
Check:
zfor corrosion
z for pushed- out pins
z connector seated correctly
z Connect any disconnected connectors.
z Make sure all other system connectors are fully seated.
z Operate the system and verify the concern is still present.
z Is the concern still present? Yes
INSTALL a new GEM.
REFER to
Section 419 - 10 .
CLEAR the DTCs. REPEAT
the GEM self- test.
No
The system is operating
correctly at this time.
Concern may have been
caused by a loose or
corroded connector. CLEAR
the DTCs. REPEAT the self-
test. Test Step Result / Action to Take
F1 CHECK IGNITION STATES
NOTE:
Verify the belt minder is activated before
diagnosing.
z Connect the diagnostic tool.
z Enter the following diagnostic mode on the diagnostic tool:
GEM PID. Yes
GO to
F2 .
No
Go To Pinpoint Test B . Klj . 17 ba
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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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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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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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z
Is the voltage equal to battery positive voltage (B+)? B2 CHECK GENERATOR A CIRCUIT 36 (YE/WH)
z
Disconnect: Generator C102c (4.6L 4V) or C102a (3.8L or 4.6L
2V).
z Measure the voltage between the generator C102c (4.6L 4V) or
C102a (3.8L or 4.6L 2V) pin 3, circuit 36 (YE/WH), harness side
and ground.
z Is the voltage equal to battery positive voltage (B+)? Yes
GO to
B3 .
No
REPAIR the circuit.
TEST the system for
normal operation. B3 CHECK I CIRCUIT 904 (LG/RD) FOR AN OPEN
z
Key in ON position.
z With the ignition switch in the RUN position and the engine off,
measure the voltage between the generator C102c (4.6L 4V) or
C102a (3.8L or 4.6L 2V) pin 1, circuit 904 (LG/RD), harness side
and ground.
z Is the voltage equal to battery positive voltage (B+)? Yes
GO to
B4 .
No
REPAIR the circuit.
TEST the system for
normal operation. B4 CHECK FOR VOLTAGE DROP IN B+ CIRCUIT 38 (YE/WH)
z
Key in START position.
z With the engine at 2,000 rpm, measure the voltage drop between
the generator C102b, circuit 38 (BK/OG), component side and
positive battery terminal. Yes
INSTALL a new
generator. REFER to
Section 414
- 02 .
TEST the system for
normal operation.
No Klj . 6 ba
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PINPOINT TEST C: THE SYSTEM OVERCHARGES (THE BATTERY
VOLTAGE IS GREATER THAN 15.5 VOLTS)
PINPOINT TEST D: THE CHARGING SYSTEM WARNING INDICATOR
IS ON WITH THE ENGINE RUNNING AND THE BATTERY z
Is the voltage drop less than 0.5 volt? REPAIR high
resistance in the B+
circuit 38 (BK/OG).
TEST the system for
normal operation.
Test Step Result / Action to Take
C1 CHECK FOR VOLTAGE DROP IN A CIRCUIT 36 (YE/WH)
z
Disconnect: Generator C102c (4.6L 4V) or C102a (3.8L or 4.6L
2V).
z Key in ON position.
z Measure the voltage drop between the generator C102c (4.6L
4V) or C102a (3.8L or 4.6L 2V) pin 3, circuit 36 (YE/WH),
harness side and positive battery terminal.
z Is the voltage drop less than 0.5 volt? Yes
GO to
C2 .
No
REPAIR the high
resistance in A circuit 36
(YE/WH). TEST the
system for normal
operation. C2 CHECK GENERATOR AND BATTERY GROUND
CONNECTIONS z
Key in OFF position.
z Check the ground connections between the voltage regulator
and the generator and the engine, and the battery and the
engine.
z Are all ground connections clean and tight? Yes
INSTALL a new
generator. REFER to
Section 414
- 02 . TEST
the system for normal
operation.
No
REPAIR ground
connections as
necessary. TEST the
system for normal
operation. Klj . 7 ba
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