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Home >> Mercury >> 2008 >> Milan Base, 3.0 1, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 114 (Interior Lighting System -- F250-F550 Super Duty) >> Diagnosis And Testing >> Interior Lighting >> Pinpoint Tests >> Pinpoint Test I: The Interior Lamps Are Inoperative From The Headlamp Switch

Pinpoint Test I: The Interior Lamps Are Inoperative From The Headlamp Switch

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
  1. I1 CHECK THE HEADLAMP SWITCH 
    • Key in OFF position.
    • Disconnect: Headlamp Switch C205b.
    • Connect a fused (10A) jumper wire between the headlamp switch C205b-2, circuit 402 (OG/LG), harness side and the headlamp switch C205b-4, circuit 57 (BK), harness side.
      Fig 1: Checking Headlamp Switch Using A Fused (10A) Jumper Wire
      G03931113Courtesy of FORD MOTOR CO.
    • Do the interior lamps illuminate? 
    • Yes  : INSTALL a new headlamp switch. REFER to EXTERIOR LIGHTING . TEST the system for normal operation.
    • No  : GO to I2.
  2. I2 CHECK CIRCUIT 402 (OG/LG) FOR AN OPEN 
    • Disconnect: Instrument Cluster C220b.
    • Measure the resistance between the instrument cluster C220b-25, circuit 402 (OG/LG), harness side and the headlamp switch C205b-2.
      Fig 2: Checking Circuit 402 (OG/LG) For An Open
      G03925102Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to I3.
    • No  : REPAIR the circuit. TEST the system for normal operation.
  3. I3 CHECK CIRCUIT 57 (BK) FOR AN OPEN 
    • Measure the resistance between the headlamp C205b-4, circuit 57 (BK) and ground.
      Fig 3: Measuring Resistance Between Headlamp C205B-4 Circuit 57 (BK) And Ground
      G03925103Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to I4.
    • No  : REPAIR the circuit. TEST the system for normal operation.
  4. I4 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION 
    • Disconnect all instrument cluster connectors.
    • Check for:
      • corrosion
      • pushed-out pins
    • Connect all instrument cluster connectors and make sure they seat correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    • Yes  : INSTALL a new instrument cluster. REFER to INSTRUMENT CLUSTER . TEST the system for normal operation.
    • No  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.