Ford 2003 Mustang Workshop Manual page 2043

Measure the resistance between the starter motor relay pin 86,
circuit 1205 (BK) and ground.
Is the resistance less than 5 ohms?
PINPOINT TEST C: THE ENGINE CRANKS SLOWLY
NOTE: Before beginning this test, be sure that the battery is tested and fully charged.
C1 CHECK THE VOLTAGE TO THE STARTER
Key in OFF position.
Measure the voltage between the starter motor
solenoid positive terminal and ground.
Is the voltage 12.5 volts or greater?
C2 CHECK MOTOR GROUND CIRCUIT
Carry out the Motor Ground Circuit test; refer to
Component Tests in this section.
Is the ground OK?
PINPOINT TEST D: UNUSUAL STARTER NOISE
Test Step
D1 CHECK THE STARTER MOTOR
MOUNTING
Inspect the starter motor mounting Yes
Test Step Result / Action to Take
Yes
GO to C2 .
No
REPAIR the circuit between the
battery and the starter solenoid.
CLEAN and TIGHTEN the
connections at the battery terminals.
TEST the system for normal
operation.
Yes
INSTALL a new starter motor.
REFER to Starter Motor—3.8L
Starter Motor—4.6L . TEST the
system for normal operation.
No
REPAIR the ground circuit as
necessary. TEST the system for
normal operation.
Result / Action to Take
or