Pinpoint Test AC: DTC U0100

Adaptive Headlighting

Pinpoint Tests

Pinpoint Test AC: DTC U0100

Normal Operation

- DTC U0100 (Lost Communication With ECM/PCM) - an on-demand DTC that sets when the Headlamp Control Module (HCM) does not receive communication from the PCM.

This pinpoint test is intended to diagnose the following:

- HCM
- PCM



PINPOINT TEST AC: DTC U0100

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AC1 REPEAT THE HCM SELF-TEST


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: HCM Self-Test.
- Clear the DTCs and repeat the HCM self-test.
- Is DTC U0100 retrieved again?

Yes
GO to AC2.

No
The vehicle is operating correctly at this time. The HCM may have temporarily lost communication with the PCM.

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AC2 CHECK OTHER MODULES FOR DTC U0100


- Enter the following diagnostic mode on the scan tool: Instrument Cluster (IC) Self-Test.
- Carry out the self-test for other modules on the High Speed Controller Area Network (HS-CAN). The IC, ABS module and Restraints Control Module (RCM), for example, communicate on the HS-CAN.
- Is DTC U0100 retrieved from any other module?

Yes
GO to AC3.

No
GO to AC4.

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AC3 CHECK FOR CORRECT PCM OPERATION


- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new PCM. REFER to Computers and Control Systems. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

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AC4 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.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new HCM. REFER to Headlamp Control Module (HCM) Service and Repair. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

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