2003 FORD MUSTANG Workshop Manual

Page 3465 of 4378

FORD MUSTANG 2003  Workshop Manual DIAGNOSIS AND TESTING 
Fog Lamps 
Refer to Wiring Diagrams Cell 
86  , Fog Lamps for schematic and connector information. 
Principles of Operation 
The fog lamps will only illuminate when the low beam

Page 3466 of 4378

FORD MUSTANG 2003  Workshop Manual Pinpoint Tests 
PINPOINT TEST O: THE FOG LAMPS ARE INOPERATIVE  Condition 
Possible Sources  Action 
�z The fog lamps are 
inoperative  �z
BJB Fuse 27 (20A). 
�z CJB Fuse 38 (20A). 
�z Circuitry. 
�z

Page 3467 of 4378

FORD MUSTANG 2003  Workshop Manual �z
Is the voltage greater than 0 volts?  O4 CHECK CIRCUIT 275 (YE) 
�z
Measure the resistance between fog lamp interrupt relay connector Pin 
4, Circuit 275 (YE), harness side and fog lamp relay conne

Page 3468 of 4378

FORD MUSTANG 2003  Workshop Manual PINPOINT TEST P: THE INDIVIDUAL FOG LAMP IS INOPERATIVE  �z
Is the resistance less than 5 ohms?  O7 CHECK CIRCUIT 1205 (BK) 
�z
Measure the resistance between fog lamp interrupt relay connector Pin 
2

Page 3469 of 4378

FORD MUSTANG 2003  Workshop Manual PINPOINT TEST Q: THE FOG LAMPS ARE ON CONTINUOUSLY  �z
Is the resistance less than 5 ohms?  No 
REPAIR Circuit 1205 
(BK). TEST the system 
for normal operation. 
Test Step  Result / Action to Take 
Q

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Page 3471 of 4378

FORD MUSTANG 2003  Workshop Manual DIAGNOSIS AND TESTING 
Reversing Lamps 
Refer to Wiring Diagrams Cell 
93  , Backup Lamps for schematic and connector information. 
Inspection and Verification  1. Verify the customer concern by opera

Page 3472 of 4378

FORD MUSTANG 2003  Workshop Manual Pinpoint Tests 
PINPOINT TEST R: THE REVERSING LAMPS ARE INOPERATIVE  �z
The individual reversing lamp 
is inoperative  �z
Bulb. 
�z Circuitry.  �z
GO to  Pinpoint  Test S  . 
�z The reversing lamps a