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 2020 Lincoln Corsair. However, it is still accessible from the selected car via links, so may be relevant.

Refer to MODULE COMMUNICATIONS NETWORK for schematic and connector information. Refer to HEADLAMPS/AUTOLAMPS 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 BJB fuse 21 (10A) is OK.

N1 CHECK THE HCM (HEADLAMP CONTROL MODULE) VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: HCM C2800.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2800-10	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to N2

No	VERIFY BJB fuse 21 (10A) 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.

N2 CHECK THE HCM (HEADLAMP CONTROL MODULE) GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2800-13	Courtesy of FORD MOTOR COMPANY	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.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2800-3	Courtesy of FORD MOTOR COMPANY	C2431-18
C2800-2	Courtesy of FORD MOTOR COMPANY	C2431-17

Are the resistances less than 3 ohms?

Yes

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 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.