Ford 2003 Mustang Workshop Manual page 3354

Is the voltage drop less than 0.5 volt?
PINPOINT TEST C: THE SYSTEM OVERCHARGES (THE BATTERY
VOLTAGE IS GREATER THAN 15.5 VOLTS)
C1 CHECK FOR VOLTAGE DROP IN A CIRCUIT 36 (YE/WH)
Disconnect: Generator C102c (4.6L 4V) or C102a (3.8L or 4.6L
2V).
Key in ON position.
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.
Is the voltage drop less than 0.5 volt?
C2 CHECK GENERATOR AND BATTERY GROUND
CONNECTIONS
Key in OFF position.
Check the ground connections between the voltage regulator
and the generator and the engine, and the battery and the
engine.
Are all ground connections clean and tight?
PINPOINT TEST D: THE CHARGING SYSTEM WARNING INDICATOR
IS ON WITH THE ENGINE RUNNING AND THE BATTERY
Test Step
REPAIR high
resistance in the B+
circuit 38 (BK/OG).
TEST the system for
normal operation.
Result / Action to Take
Yes
GO to C2 .
No
REPAIR the high
resistance in A circuit 36
(YE/WH). TEST the
system for normal
operation.
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.