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Home >> Mercury >> 2008 >> Milan Base, 3.0 1, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 721 (Exterior Lighting System) >> Diagnostic Tests >> Fog Lamps >> Pinpoint Tests >> Pinpoint Test R: The Fog Lamps Are Inoperative >> Pinpoint Test R: The Fog Lamps Are Inoperative

Pinpoint Test R: The Fog Lamps Are Inoperative

WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. R1 CHECK THE HEADLAMPS HIGH BEAM OPERATION 
    • Key in OFF position.
    • Place the headlamp switch in the HEADLAMPS ON position.
    • Place the multifunction switch in the HIGH BEAM, then LOW BEAM positions.
    • Do the headlamp high beams operate correctly? 
    1. YES  : TURN the headlamp switch off. Go to  R2 .
    2. NO  : REFER to Headlamps  in this article.
  2. R2 CHECK THE FOG LAMP RELAY 
    • Disconnect: Fog Lamp Relay
    • Carry out the fog lamp relay component test. Refer to COMPONENT TESTING.
    • Is the relay OK? 
    1. YES  : Go to  R3.
    2. NO  : INSTALL a new fog lamp relay. TEST the system for normal operation.
  3. R3 CHECK FOR VOLTAGE TO THE FOG LAMP RELAY 
    • Place the headlamp switch in the PARKING LAMPS ON position and engage the fog lamp switch.
    • Measure the voltage between the fog lamp relay pin 2, circuit 188 (WH/BK), harness side and ground.
      • Fig 1: Checking Voltage To Fog Lamp Relay
      GF0004616Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    1. YES  : TURN the headlamp switch off. Go to  R4 .
    2. NO  : TURN the headlamp switch off. Go to  R6 .
  4. R4 CHECK THE CJB 
    • Connect a fused (15A) jumper wire between the fog lamp relay pin 3, harness side and the fog lamp relay pin 5, circuit 478 (TN/OG), harness side.
      • Fig 2: Checking CJB
      GF0004617Courtesy of FORD MOTOR CO.
    • Do the fog lamps illuminate? 
    1. YES  : REPAIR or INSTALL a new CJB. TEST the system for normal operation.
    2. NO  : LEAVE the jumper wire connected. Go to  R5 .
  5. R5 CHECK CIRCUIT 478 (TN/OG) FOR AN OPEN 
    • Disconnect: CJB C270a
    • Measure the voltage between the CJB C270a pin 12, circuit 478 (TN/OG), component side and ground.
      • Fig 3: Checking Circuit 478 (TN/OG) For An Open
      GF0004618Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    1. YES  : REPAIR the circuit. TEST the system for normal operation.
    2. NO  : VERIFY the CJB fuse 17 (15A) is OK. If OK, REPAIR or INSTALL a new CJB. TEST the system for normal operation.
  6. R6 CHECK THE HEADLAMP SWITCH OUTPUT 
    • Disconnect: CJB C270h
    • Place the headlamp switch in the PARKING LAMPS ON position and engage the fog lamp switch.
    • Measure the voltage between the CJB C270h-5, circuit 188 (WH/BK), harness side and ground.
      • Fig 4: Checking Headlamp Switch Output
      GF0004619Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    1. YES  : REPAIR or INSTALL a new CJB. TEST the system for normal operation.
    2. NO  : TURN the headlamp switch off. Go to  R7 .
  7. R7 CHECK THE HEADLAMP SWITCH 
    • Carry out the headlamp switch component test. Refer to COMPONENT TESTING.
    • Is the headlamp switch OK? 
    1. YES  : REPAIR circuit 188 (WH/BK). TEST the system for normal operation.
    2. NO  : INSTALL a new headlamp switch. REFER to Headlamp Switch  in this article. TEST the system for normal operation.
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