Ford 2003 Mustang Workshop Manual page 3351

Symptom Chart
Condition
Battery is discharged or voltage is
low
The charging system warning
indicator is on with the engine
running (the system voltage does
not increase)
The system overcharges (the
battery voltage is greater than 15.5
volts)
The charging system warning
indicator is on with the engine
running and the battery increases
voltage
The charging system warning
indicator is off with the ignition
switch in the RUN position and the
engine off
The charging system warning
indicator flickers or is intermittent
The generator is noisy
Radio interference
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
Possible Sources
Circuitry.
High key-off current
drain(s).
Battery.
Generator.
Circuitry.
Voltage regulator.
Generator.
Circuitry.
Voltage regulator.
Generator.
Circuitry.
Instrument cluster.
Voltage regulator.
Generator.
Bulb.
Circuitry.
Instrument cluster.
Voltage regulator.
Generator.
Central junction box
(CJB) fuse 5 (15A).
Generator
connector
unplugged (C102a).
Circuitry.
Generator.
Bolts or brackets.
Drive belt.
Generator or pulley.
Generator.
Circuitry.
In-vehicle
entertainment
system.
Action
Go To
Pinpoint
Test A .
Go To
Pinpoint
Test B .
Go To
Pinpoint
Test C .
Go To
Pinpoint
Test D .
Go To
Pinpoint
Test E .
Go To
Pinpoint
Test F .
Go To
Pinpoint
Test G .
Go To
Pinpoint
Test F .