Pinpoint Test AC: DTC U0100:87

Adaptive Headlighting

Pinpoint Test AC: DTC U0100:87

- DTC U0100:87 (Lost Communication With ECM/PCM "A": Missing Message) - sets continuous in the Headlamp Control Module (HCM) if data messages received from the PCM over the High Speed Controller Area Network (HS-CAN) are missing. For a complete list of all network messages, refer to Module Communications Network Testing and Inspection.

This pinpoint test is intended to diagnose the following:

- HCM
- PCM


PINPOINT TEST AC: DTC U0100:87

NOTE: If new modules were installed prior to the DTC being set, the module configuration may be incorrectly set during the Programmable Module Installation (PMI) or the PMI may not have been carried out.

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AC1 VERIFY THAT THE SCAN TOOL CAN COMMUNICATE WITH THE PCM

- Ignition ON.
- Check that a vehicle session can be established using the scan tool.
- Can a vehicle session be established?

Yes
GO to AC2.

No
REFER to Module Communications Network Testing and Inspection to diagnose no communication with the PCM.

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AC2 CHECK THE IPC CONTINUOUS MEMORY DTCs

- Enter the following diagnostic mode on the scan tool: HCM Self-Test.
- Clear the DTCs. Repeat the HCM self-test.
- Is DTC U0100:87 retrieved again?

Yes
GO to AC3.

No
The system is operating correctly at this time. The DTC may have been set due to high network traffic or an intermittent fault condition.

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AC3 RETRIEVE THE RECORDED DTCs FROM THE HCM SELF-TEST

- Check for recorded DTCs from the HCM self-test.
- Is DTC U3003:16 or DTC U3003:17 recorded?

Yes
For DTC U3003:16, GO to Pinpoint Test AH. Pinpoint Test AH: DTC U3003:16

For DTC U3003:17 GO to Pinpoint Test AI. Pinpoint Test AI: DTC U3003:17

No
GO to AC4.

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AC4 CHECK FOR DTC U0100 SET IN OTHER MODULES

- Enter the following diagnostic mode on the scan tool: Self-Test.
- Retrieve the continuous memory DTCs from all modules.
- Is DTC U0100 set in the Instrument Panel Cluster (IPC) or the Restraints Control Module (RCM)?

Yes
INSTALL a new PCM. REFER to Electronic Engine Controls - Service and Repair.

TEST the system for normal operation.

No
INSTALL a new HCM. REFER to Headlamp Control Module (HCM) Service and Repair. TEST the system for normal operation.

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