Pinpoint Test S: The Headlamp Control Module 2 (HCM-2) Does Not Respond To The Scan Tool

Communications Network

Pinpoint Tests

Pinpoint Test S: The Headlamp Control Module 2 (HCM-2) Does Not Respond To The Scan Tool

Refer to Wiring Diagram Set 14, Module Communications Network for schematic and connector information. Diagrams By Number

Normal Operation

The Headlamp Control Module 2 (HCM-2) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN)) and circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the MS-CAN) connection to the HCM-2. Voltage for the HCM-2 is provided by circuit CBP31 (BU/OG). Circuit GD133 (BK) provides ground.

This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- HCM-2



PINPOINT TEST S: THE HCM-2 DOES NOT RESPOND TO THE SCAN TOOL

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTE: The steps in this pinpoint test are carried out from the headlamp jumper harness connection, not the module itself.

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S1 CHECK THE HCM-2 VOLTAGE SUPPLY CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: Inline HCM-2 C913.
- Ignition ON.
- Measure the voltage between the inline HCM-2 C913-A, circuit CBP31 (BU/OG), harness (female) side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to S2.

No
VERIFY the Smart Junction Box (SJB) fuse 31 (10A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the short circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.

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S2 CHECK THE HCM-2 GROUND CIRCUIT FOR AN OPEN


- Measure the resistance between the inline HCM-2 C913-E, circuit GD133 (BK), harness (female) side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to S3.

No
REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.

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S3 CHECK THE MS-CAN CIRCUITS BETWEEN THE HCM-2 AND THE DLC FOR AN OPEN


- Measure the resistance between the inline HCM-2 C913-C, circuit VDB06 (GY/OG), harness (female) side and the DLC C251-3, circuit VDB06 (GY/OG), harness side.




- Measure the resistance between the inline HCM-2 C913-F, circuit VDB07 (VT/OG), harness (female) side and the DLC C251-11, circuit VDB07 (VT/OG), harness side.




- Are the resistances less than 5 ohms?

Yes
GO to S4.

No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.

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S4 CHECK FOR CORRECT HCM-2 OPERATION


- Disconnect the HCM-2 connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the HCM-2 connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new HCM-2. 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.

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