Pinpoint Test C: One High Beam Headlamp Is Inoperative

WARNING: This page is about a different car, the 2010 Mercury Milan, 2010 Lincoln MKZ, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

C1 CHECK FOR VOLTAGE TO THE HEADLAMP
- Ignition OFF.
- Disconnect: Inoperative Headlamp.
- Place the headlamp switch in the HEADLAMPS ON position.
- Place the multifunction switch in the HIGH BEAM position.
- Measure the voltage between the LH headlamp C1021-7, circuit CLF08 (YE/VT), harness side and ground; or between the RH headlamp C1041-7, circuit CLF08 (YE/VT), harness side and ground.
  
  Fig 1: Measuring Voltage Between LH Headlamp C1021-7 & Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes: For Fusion or MKZ, GO to C2.
  For Milan, INSTALL a new headlamp assembly. REFER to Removal and Installation . TEST the system for normal operation.
- No: REPAIR circuit CLF08 (YE/VT) for an open. TEST the system for normal operation.
C2 CHECK FOR VOLTAGE TO THE HEADLAMP USING THE HIGH BEAM GROUND PIN
- Measure the voltage between the LH headlamp C1021-7, circuit CLF08 (YE/VT), harness side and the LH headlamp C1021-4, circuit GD121 (BK/YE), harness side; or between the RH headlamp C1041-7, circuit CLF08 (YE/VT), harness side and the RH headlamp C1041-4, circuit GD123 (BK/GY), harness side.
  
  Fig 2: Measuring Voltage Between LH Headlamp C1021-7 & C1021-4
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes: REPAIR or INSTALL a new headlamp assembly. REFER to Removal and Installation . TEST the system for normal operation.
- No: REPAIR circuit GD121 (BK/YE) (LH headlamp) or circuit GD123 (BK/GY) (RH headlamp) for an open. TEST the system for normal operation.