Pinpoint Test I: DTC U0100

Adaptive Headlighting

Pinpoint Test I: 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 vehicle speed or transaxle gear messages from the PCM for more than 5 seconds.

This pinpoint test is intended to diagnose the following:

- Communication network concern

- PCM

- Left headlamp assembly

PINPOINT TEST I : DTC U0100

I1 VERIFY THE SCAN TOOL CAN COMMUNICATE WITH THE PCM

- Connect the scan tool.

- Check that a vehicle session can be established using the scan tool.

Can a vehicle session be established?

Yes
GO to I2.

No
REFER to Information Bus, The PCM Does Not Respond To The Scan Tool. Pinpoint Test A: The PCM Does Not Respond To The Scan Tool

I2 CHECK THE HCM (Headlamp Control Module) CONTINUOUS MEMORY DTCs

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: HCM (Headlamp Control Module) Self-Test.

- Clear the DTCs and repeat the HCM (Headlamp Control Module) self-test.

Is DTC U0100 retrieved again?

Yes
GO to I3.

No
The vehicle is operating correctly at this time. The HCM (Headlamp Control Module) may have temporarily lost communication with the PCM.

I3 CHECK FOR DTC U0100:87 OR 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 U0100:87 or DTC U0100 set in any other module?

Yes
INSTALL a new PCM. TEST the system for normal operation.

No
INSTALL a new left headlamp assembly. REFER to Headlamp Assembly Service and Repair. TEST the system for normal operation