Ford 2003 Mustang Workshop Manual page 2348

Visually inspect the lead frame and connectors for
damage.
Key in ON position.
Measure the voltage with the positive lead to VPWR
solenoid pin and negative lead to a good ground.
Is the voltage greater than 10 volts?
A6 ELECTRICAL SIGNAL CHECK
Measure the voltage with the positive lead connected to
VPWR solenoid pin and the negative lead to the signal
pin of the appropriate solenoid.
Enter the following diagnostic mode on the diagnostic
tool: Trans-Bench Mode.
Select Parameter SSA, SSB or TCC.
Select "ON".
Press "SEND".
Turn the solenoids ON and OFF, while monitoring the
voltage, solenoid state on the scan tool (ON and OFF),
and listen for the solenoid to activate (click).
Measure the voltage with the positive lead to VPWR pin
and the negative lead to the TCC pin.
Enter the following diagnostic mode on the diagnostic
tool: Select Parameter TCC.
Select "ON".
Press "SEND".
Turn the solenoid ON and OFF, while monitoring the
voltage, solenoid state on the scan tool (ON and OFF),
GO to A6 .
No
CHECK for open or short circuit
in harness, or solenoid.
Yes
GO to A7 .
No
CHECK for open or short circuit
in harness, solenoid or a PCM
concern.