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PINPOINT TEST N : The Headlamp Control Module (HCM) Does Not Respond To The Diagnostic Scan Tool

WARNING: This page is about a different car, the 2016 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery, Mounting and Cables .

  1. N1 CHECK THE HCM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

    • Ignition OFF.
    • Disconnect: HCM C2129 .
    • Ignition ON.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2129-24
      GFD134422Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the voltage greater than 11 volts? 

    Yes  GO to  N2.
    No  VERIFY the BJB fuse 55 (15A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM Electrical Wiring Diagram Introduction to identify the possible causes of the circuit short.

  2. N2 CHECK THE HCM GROUND CIRCUIT FOR AN OPEN

    • Ignition OFF.
    • Disconnect: Negative Battery Cable.
    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2129-1
      GFD134423Courtesy of FORD MOTOR COMPANY
      		 Ground

    Is the resistance less than 3 ohms? 

    Yes  GO to  N3.
    No  REPAIR the circuit.

  3. N3 CHECK THE HS-CAN CIRCUITS BETWEEN THE HCM AND THE DLC FOR AN OPEN

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2129-19
      GFD134423Courtesy of FORD MOTOR COMPANY
      		 C251-6
      C2129-7
      GFD134423Courtesy of FORD MOTOR COMPANY
      		 C251-14

    Are the resistances less than 3 ohms? 

    Yes  CONNECT the negative battery cable. GO to  N4.
    No  REPAIR the circuit in question.

  4. N4 CHECK FOR CORRECT HCM OPERATION

    • Ignition OFF.
    • Disconnect and inspect the HCM connector and related in-line connectors.
    • Repair:
      • corrosion (replace connector or terminals - clean module pins)
      • damaged or bent pins - replace terminals/pins
      • pushed-out pins - replace pins as necessary
    • Reconnect the HCM connector and related in-line connectors. Make sure they seat and latch correctly.
    • Operate the system and verify the concern is still present.

    Is the concern still present? 

    Yes  CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, discontinue this test and follow TSB instructions. If no TSBs address this concern, INSTALL a new HCM. REFER to Exterior Lighting .
    No  The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector.
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