Ford 2003 Mustang Workshop Manual page 3468

Is the resistance less than 5 ohms?
O7 CHECK CIRCUIT 1205 (BK)
Measure the resistance between fog lamp interrupt relay connector Pin
2, Circuit 1205 (BK), and ground.
Is the resistance less than 5 ohms?
O8 CHECK THE FOG LAMP SWITCH
Measure the resistance between fog lamp switch C240 Pin 1, Circuit
188 (WH/BK), connector side and fog lamp switch C240 Pin 2, Circuit
14 (BN), connector side with the fog lamp switch on.
Is the resistance less then 5 ohms?
PINPOINT TEST P: THE INDIVIDUAL FOG LAMP IS INOPERATIVE
P1 CHECK THE GROUND TO THE FOG LAMP
Key in OFF position.
Disconnect: Inoperative Fog Lamp.
Measure the resistance between inoperative fog lamp C162 Pin
1 (RH) or C152 Pin 1 (LH), Circuit 1205 (BK), harness side and
ground.
Test Step
Yes
GO to O8 .
No
REPAIR the
circuit. TEST the
system for
normal
operation.
Yes
REPAIR Circuit
478 (TN/OG).
TEST the system
for normal
operation.
No
INSTALL a new
fog lamp switch.
TEST the system
for normal
operation.
Result / Action to
Take
Yes
REPAIR Circuit 478
(TN/OG) for open.
TEST the system for
normal operation.