Pinpoint Test N : The HCM (Headlamp Control Module) Does Not Respond To The Diagnostic Scan Tool
WARNING: This page is about a different car, the 2019 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.
- Refer to OEM WIRING DIAGRAMS FOR MODULE COMMUNICATIONS NETWORK - CELL 14
for schematic and connector information. Refer to OEM WIRING DIAGRAMS FOR HEADLAMPS/AUTOLAMPS - CELL 85
for schematic and connector information.
Normal Operation and Fault Conditions
The HCM communicates on the HS-CAN2.
Possible Sources
- Fuse
- Wiring, terminals and connector
- HCM
Visual Inspection and Pre-checks
- Verify BCM fuse 20 (7.5A) is OK.
- N1 CHECK THE HCM (HEADLAMP CONTROL MODULE) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: HCM C2129.
- Ignition ON.
- Measure:
Positive Lead Measurement / Action Negative Lead C2129-24 Ground
Is the voltage greater than 11 volts?
Yes GO to N2 No VERIFY BCM fuse 20 (7.5A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams service information to identify the possible causes of the circuit short. - N2 CHECK THE HCM (HEADLAMP CONTROL MODULE) GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure:
Positive Lead Measurement / Action Negative Lead C2129-4 Ground
Is the resistance less than 3 ohms?
Yes GO to N3 No REPAIR the circuit. - N3 CHECK THE HS-CAN2 (HIGH-SPEED CONTROLLER AREA NETWORK 2) CIRCUITS BETWEEN THE HCM (HEADLAMP CONTROL MODULE) AND THE GWM (GATEWAY MODULE A) FOR AN OPEN
- Disconnect GWM C2431.
Are the resistances less than 3 ohms?
Yes CONNECT the GWM. GO to N4 No REPAIR the circuit in question. - N4 CHECK FOR CORRECT HCM (HEADLAMP CONTROL MODULE) OPERATION
- Ignition OFF.
- Disconnect and inspect the HCM connector.
- Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
- Reconnect the HCM connector. Make sure it seats and latches correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new HCM. REFER to: Headlamp Control Module (HCM) . No The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.