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Pinpoint Test F: The Headlamp Control Module (HCM) Does Not Respond To The Scan Tool

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Module Communications Network for schematic and connector information.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Headlamps/Autolamps for schematic and connector information.

Normal Operation 

The headlamp control module (HCM) communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the HCM. The HCM shares the HS-CAN with the PCM, the accessory protocol interface module (APIM), the ABS module, the 4X4 control module (if equipped), the restraints control module (RCM), the occupant classification system module (OCSM), the steering angle sensor module (SASM) (if equipped) and the instrument cluster (IC). Voltage to the HCM is supplied by circuit CBB51 (BN). Ground is supplied by circuit GD120 (BK/GN).

This pinpoint test is intended to diagnose the following:

PINPOINT TEST F: THE HEADLAMP CONTROL MODULE (HCM) DOES NOT RESPOND TO THE SCAN TOOL 

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: HCM testing is carried out at the LH headlamp assembly connector.
  1. F1 CHECK THE HCM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: LH Headlamp Assembly C1021b
    • Key in ON position.
      • Fig 1: Measuring Voltage Between Adaptive Front Lighting Module C1021B-3, Circuit CBB51 (BN)
      GF0032347Courtesy of FORD MOTOR CO.
    • Measure the voltage between the LH headlamp assembly C1021b-3, circuit CBB51 (BN), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  F2.
    2. NO  : VERIFY the battery junction box (BJB) fuse 51 (5A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. F2 CHECK THE HCM GROUND CIRCUIT FOR AN OPEN 
    • Key in OFF position.
      • Fig 2: Measuring Resistance Between Adaptive Front Lighting Module C1021B-9, Circuit GD120 (BK/GN)
      GF0032348Courtesy of FORD MOTOR CO.
    • Measure the resistance between the LH headlamp assembly C1021b-9, circuit GD120 (BK/GN), harness side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  F3.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  3. F3 CHECK THE HS-CAN CIRCUITS BETWEEN THE HCM AND THE DATA LINK CONNECTOR (DLC) FOR AN OPEN 
      Fig 3: Measuring Resistance Between Adaptive Front Lighting Module C1021B-6, Circuit VDB04 (WH/BU) & DLC C251-6
      GF0032349Courtesy of FORD MOTOR CO.
    • Measure the resistance between the LH headlamp assembly C1021b-6, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
      • Fig 4: Measuring Resistance Between Adaptive Front Lighting Module C1021B-12, Circuit VDB05 (WH) & DLC C251-14
      GF0032350Courtesy of FORD MOTOR CO.
    • Measure the resistance between the LH headlamp assembly C1021b-12, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
    • Are the resistances less than 5 ohms? 
    1. YES  : Go to  F4.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. F4 CHECK FOR CORRECT HCM OPERATION 
    • Disconnect the HCM connector.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect the HCM connector and make sure it seats correctly.
    • Verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new HCM. REFER to EXTERIOR LIGHTING article. CLEAR the DTCs. REPEAT the network test with the scan tool.

      If the concern is still present, INSTALL a new LH headlamp assembly. REFER to EXTERIOR LIGHTING article. CLEAR the DTCs. REPEAT the network test with the scan tool.

    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
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