Ford 2003 Mustang Workshop Manual page 3280

Operate the system and verify the concern is still present.
Is the concern still present?
PINPOINT TEST C: INCORRECT OIL PRESSURE GAUGE
INDICATION
C1 CHECK THE INSTRUMENT CLUSTER OPERATION
CAUTION: Use the correct probe adapter(s) when
making measurements. Failure to use the correct probe
adapter(s) may damage the connector.
Connect the diagnostic tool.
Key in ON position.
Enter the following diagnostic mode on the diagnostic tool:
Instrument Cluster Active Command.
Trigger the instrument cluster active command OIL GAUGE.
Scroll to 0%, 50%, and 100%.
Did the gauge display L at 0%, the middle of the gauge at
50%, and H at 100%?
C2 CHECK CIRCUIT 31 (WH/RD) FOR OPEN OR SHORT TO
GROUND
Key in OFF position.
Disconnect: Instrument Cluster C220b.
Disconnect: Oil Pressure Switch C103.
Measure the resistances between the instrument cluster C220b
pin 16, circuit 31 (WH/RD), harness side and the oil pressure
switch C103, circuit 31 (WH/RD), harness side; and between the
instrument cluster C220b pin 16, circuit 31 (WH/RD), harness
side and ground.
Is the resistance less than 5 ohms between the instrument
cluster and the oil pressure switch, and greater than 10,000
ohms between the instrument cluster and ground?
C3 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
Disconnect all instrument cluster connectors.
Test Step
normal operation.
No
The system is
operating correctly at
this time. Concern may
have been caused by
a loose or corroded
connector. CLEAR the
DTCs. REPEAT the
self-test.
Result / Action to
Take
Yes
GO to C2 .
No
GO to C3 .
Yes
INSTALL a new oil
pressure switch. TEST
the system for normal
operation.
No
REPAIR the circuit.
TEST the system for
normal operation.
Yes
INSTALL a new