Ford 2003 Mustang Workshop Manual page 3068

Is the resistance reading less than 10,000 ohms?
C13 CHECK CIRCUIT 198 (DG/OG) FOR A SHORT TO
GROUND
Connect: A/C Pressure Cut-off Switch C1078.
Measure the resistance between PCM C175-41, circuit
198 (DG/OG), harness side and ground.
Is the resistance less than 10,000 ohms?
C14 CHECK THE A/C PRESSURE CUT-OFF SWITCH
Disconnect: A/C Pressure Cut-off Switch C1078.
Measure the resistance between the Rotunda EEC-V
Breakout Box pin 41, circuit 198 (DG/OG), and ground.
Is the resistance less than 10,000 ohms?
C15 CHECK THE FUNCTION SELECTOR SWITCH
Key in OFF position.
Connect: Function Selector Switch C294c.
Disconnect: A/C Cycling Switch C130.
Key in ON position.
Turn the function selector switch to the A/C position.
Measure the voltage between C130-4, circuit 348 (VT),
harness side and ground.
Yes
GO to C15 .
No
INSTALL a new A/C fuse (15A).
TEST the system for normal
operation. If the fuse opens,
install a new PCM. REFER to
the Powertrain
Control/Emissions Diagnosis
(PC/ED) manual.
Yes
REPAIR circuit 198 (DG/OG)
for a short to ground. TEST the
system for normal operation.
No
INSTALL a new A/C pressure
cut-off switch. REFER to
Section 412-03 .
Yes
GO to C17 .
No
GO to C16 .