Pinpoint Test J: DTC U0100

Anti-Lock Control

Pinpoint Tests

Pinpoint Test J: DTC U0100

Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number

Normal Operation
- DTC U0100 (Lost Communication With ECM/PCM) - this DTC sets in continuous memory and on-demand if the brake pedal position switch, and traction control messages that should be received from the ECM/PCM are missing for 5 seconds or longer.

This pinpoint test is intended to diagnose the following:
- Communication network concern
- PCM
- ABS module

PINPOINT TEST J: DTC U0100

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J1 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 J2.

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

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J2 CHECK THE ABS MODULE CONTINUOUS MEMORY DTCs


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: ABS Module Self-Test.
- Clear the DTCs.
- Wait 10 seconds.
- Repeat the ABS module self-test.
- Is DTC U0100 retrieved again?

Yes
GO to J3.

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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J3 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST


- Check for recorded DTCs from the PCM Key ON Engine OFF (KOEO) self-test.
- Is DTC P0562 or P0563 recorded?

Yes
REFER to Electronic Engine Controls Testing and Inspection.

No
GO to J4.

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J4 CHECK FOR DTC U0100 SET IN OTHER MODULES


- Ignition ON.
- 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 Transmission Control Module (TCM) (if equipped) or DTC U0100 in the Instrument Cluster (IC)?

Yes
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. TEST the system for normal operation.

No
INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module Service and Repair. TEST the system for normal operation.

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