Ford 2003 Mustang Workshop Manual page 3467

Is the voltage greater than 0 volts?
O4 CHECK CIRCUIT 275 (YE)
Measure the resistance between fog lamp interrupt relay connector Pin
4, Circuit 275 (YE), harness side and fog lamp relay connector Pin 85,
Circuit 275 (YE), harness side.
Is the resistance less than 5 ohms?
O5 CHECK CIRCUIT 477 (LB/BK) FOR OPEN
Measure the voltage between fog lamp relay connector Pin 30, Circuit
477 (LB/BK), harness side and ground.
Is the voltage greater than 10 volts?
O6 CHECK CIRCUIT 188 (WH/BK)
Disconnect: Fog Lamp Switch C240.
Measure the resistance between fog lamp switch C240 Pin 1, Circuit
188 (WH/BK), harness side and fog lamp relay connector Pin 86,
Circuit 188 (WH/BK), harness side; and between fog lamp switch C240
Pin 1, Circuit 188 (WH/BK), harness side and ground.
Yes
GO to O5 .
No
REPAIR the
circuit. TEST the
system for
normal
operation.
Yes
GO to O6 .
No
REPAIR the
circuit. TEST the
system for
normal
operation.
Yes
GO to O7 .
No
REPAIR the
circuit. TEST the
system for
normal
operation.