Ford 2003 Mustang Workshop Manual page 3073

Is the resistance less than 5 ohms?
PINPOINT TEST D: THE A/C IS ALWAYS ON
D1 CHECK PCM PID WACF
Turn the function selector switch to the OFF position.
Key in ON position.
Enter the following diagnostic mode on the diagnostic
tool: PCM PID WACF.
Does the PCM PID WACF read YES?
D2 CHECK PID ACCS WITH A/C OFF
Enter the following diagnostic mode on the diagnostic
tool: PCM PID ACCS.
Does the PCM PID ACCS read ON?
D3 CHECK FOR A FALSE INPUT SIGNAL TO THE PCM
Key in OFF position.
Disconnect: PCM C175.
Key in ON position.
Turn the function selector switch to the OFF position.
Measure the voltage between PCM C175-41, circuit 198
(DG/OG) harness side and ground.
Is the voltage greater than 10 volts?
D4 CHECK CIRCUIT 198 (DG/OG) FOR A SHORT TO B+
Key in OFF position.
Disconnect: Function Selector Switch C294c.
Connect: PCM C175.
Key in ON position.
Measure the voltage at the function selector switch
Test Step
No
REPAIR circuit 1205 (BK) for
an open. TEST the system for
normal operation.
Result / Action to Take
Yes
REPAIR circuit 331 (PK/YE) for
a short to ground. TEST the
system for normal operation.
No
GO to D2 .
Yes
GO to D3 .
No
GO to D5 .
Yes
GO to D4 .
No
INSTALL a new powertrain
control module. REFER to
Section 303-14 . TEST the
system for normal operation.
Yes
REPAIR circuit 348 (PK) for a
short to B+. TEST the system
for normal operation.