TSB : Pinpoint Test R: The Fog Lamps Are Inoperative

Details

R1 CHECK LOW BEAM HEADLAMPS Inspect the low beam headlamp operation. Do the low beams operate correctly? Yes: GO to R2. No: REPAIR the headlamp concerns; REFER to HEADLAMPS . TEST the system for normal operation. R2 CHECK FOG LAMP RELAY GROUND Disconnect: Fog Lamp Relay. Measure the resistance between fog lamp relay pin 2, circuit 57 (BK), harness side, and ground. Fig 1: Measuring Resistance Between Fog Lamp Relay Pin 2, Circuit 57 (BK), Harness Side & Ground Courtesy of FORD MOTOR CO. Is the resistance less than 5 ohms? Yes: GO to R3. No: REPAIR the circuit. TEST the system for normal operation. R3 CHECK FOG LAMP RELAY VOLTAGE Measure the voltage between fog lamp relay pin 3, circuit 474 (OG/LG), harness side, and ground. Fig 2: Measuring Voltage Between Fog Lamp Relay Pin 3, Circuit 474 (OG/LG), Harness Side & Ground Courtesy of FORD MOTOR CO. Is the voltage greater than 10 volts? Yes: GO to R4. No: REPAIR the circuit. TEST the system for normal operation. R4 CHECK FOG LAMP SWITCH SIGNAL NOTE: Headlamps must be ON, and in the low beam position. Place the fog lamp switch in the ON position. Measure the voltage between fog lamp relay pin 1, circuit 275 (YE), harness side, and ground. Fig 3: Measuring Voltage Between Fog Lamp Relay Pin 1, Circuit 275 (YE), Harness Side & Ground Courtesy of FORD MOTOR CO. Is the voltage greater than 10 volts? Yes: GO to R5. No: GO to R7 . R5 CHECK THE FOGLAMP RELAY Carry out the relay test for the fog lamp relay; refer to COMPONENT TESTING article. Is the fog lamp relay OK? Yes: GO to R6. No: INSTALL a new fog lamp relay. TEST the system for normal operation. R6 CHECK FOG LAMP GROUND Disconnect: Inoperative Fog Lamp. Measure the resistance between RH fog lamp C162 pin 1, or LH fog lamp C152 pin 1, circuit 57 (BK), harness side and ground. Fig 4: Measuring Resistance Between RH Fog Lamp C162 Pin 1 Or LH Fog Lamp C152 Pin 1, Circuit 57 (BK), Harness Side & Ground Courtesy of FORD MOTOR CO. Is the resistance less than 5 ohms? Yes: REPAIR Circuit 478 (TN/OG). TEST the system for normal operation. No: REPAIR circuit 57 (BK). TEST the system for normal operation. R7 CHECK CIRCUIT 188 (WH/BK) Disconnect: CJB C270b. Measure the resistance between headlamp switch C205b pin 2, circuit 188 (WH/BK), harness side, and CJB C270b pin 2, circuit 188 (WH/BK), harness side. Fig 5: Measuring Resistance Between Headlamp Switch C205B Pin 2, Circuit 188 (WH/BK), Harness Side & CJB C270B Pin 2 Circuit 188 (WH/BK), Harness Side Courtesy of FORD MOTOR CO. Is the resistance less than 5 ohms? Yes: INSTALL a new headlamp switch; REFER to LAMP SWITCH - HEADLAMP . No: REPAIR the circuit. TEST the system for normal operation.