Pinpoint Test F: The HCM Does Not Respond To The Scan Tool

WARNING: This page is about a different car, the 2013 Lincoln MKX and 2013 Ford Edge. 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.

NOTE: Failure to disconnect the battery when instructed results in false resistance readings. Refer to BATTERY, MOUNTING AND CABLES .

F1 CHECK THE HCM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
NOTE: Perform HCM testing at the LH headlamp connector.
- Ignition OFF.
- Disconnect: LH Headlamp C1021B.
- Ignition ON.
- Measure the voltage between the LH headlamp C1021B-3, circuit CBB89 (VT/GY), harness side and ground.
  
  Fig 1: Measuring Voltage Between LH Headlamp C1021B-3, Circuit CBB89 (VT/GY), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
  - YES : GO to F2.
  - No : VERIFY the Battery Junction Box (BJB) fuse 89 (5A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the appropriate SYSTEM WIRING DIAGRAMS (Edge) article or SYSTEM WIRING DIAGRAMS (MKX) article to identify the possible causes of the circuit short. CLEAR the DTCs. REPEAT the network test with the scan tool.
F2 CHECK THE HCM GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the LH headlamp C1021B-9, circuit GD120 (BK/GN), harness side and ground.
  
  Fig 2: Measuring Resistance Between LH Headlamp C1021B-9, Circuit GD120 (BK/GN), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
  - YES : GO to F3.
  - No : REPAIR the circuit. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
F3 CHECK THE HS-CAN CIRCUITS BETWEEN THE HCM AND THE DLC FOR AN OPEN
- Measure the resistance between the LH headlamp C1021B-6, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
  
  Fig 3: Measuring Resistance Between LH Headlamp C1021B-6, Circuit VDB04 (WH/BU) And DLC C251-6, Circuit VDB04 (WH/BU), Harness Side
  Courtesy of FORD MOTOR CO.
- Measure the resistance between the LH headlamp C1021B-12, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
  
  Fig 4: Measuring Resistance Between LH Headlamp C1021B-12, Circuit VDB05 (WH) And DLC C251-14, Circuit VDB05 (WH), Harness Side
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
  - YES : CONNECT the negative battery cable. GO to F4.
  - No : REPAIR the circuit in question. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
F4 CHECK FOR CORRECT HCM OPERATION
- Disconnect the LH headlamp connector.
- Check for:
  - Corrosion
  - Damaged pins
  - Pushed-out pins
- Connect the LH headlamp connector and make sure it seats correctly.
- Verify the concern is still present.
- Is the concern still present?
  - YES : INSTALL a new HCM that is integral to the LH headlamp assembly. REFER to EXTERIOR LIGHTING . CLEAR the DTCs. REPEAT the network test with the scan tool.
  - 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.