Body Control System

U0100 - LOST COMMUNICATION WITH ECM/PCM

U0100 - Lost Communication With ECM/PCM:

WHEN MONITORED
- With the ignition on
- Battery voltage between 10 and 16 volts
- IOD fuse installed
- FCM is configured correctly

SET CONDITION
Bus messages not received from the ECM/PCM for approximately 2 to 5 seconds.

POSSIBLE CAUSES
- CAN B or CAN C bus circuits open or shorted
- DTCS related to battery voltage, ignition, or VIN messages
- FCM not configured correctly
- ECM/PCM power and ground
- ECM/PCM
- Module that set this DTC

Diagnostic Test

1. VERIFY DTC IS ACTIVE

NOTE: Ensure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.

With the scan tool, read active DTCs.

Q: Is this DTC active?

YES: Go To 2
NO: Refer to the Stored Lost Communication test procedure.

2. CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS

With the scan tool, read all active DTCs from all modules.

NOTE: Check for FCM configuration, CAN B or C hardware electrical, VIN Missing/Mismatch, battery or ignition related DTCs.

Q: Does the scan tool display any active DTCs to the conditions listed above?

YES: Diagnose and repair the DTC.
NO: Go To 3

3. VERIFY THAT THE ECM/PCM IS ACTIVE ON THE BUS

Turn the ignition on.
With the scan tool, select Network View and select Advanced.
Verify that the ECM/PCM is active on the bus.

Q: Is the ECM/PCM active on the bus?

YES: Go To 4
NO: Refer to Manufacturer Code Charts / Communication for the No Response test procedure.

4. CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS

With the scan tool, select Network View and select Advanced.

Q: Is there more than one module with active DTCs "Logged Against" the ECM/PCM?

YES: Replace/update the ECM/PCM. Perform the appropriate VERIFICATION TEST. Vehicle Theft Security Verification Tests
NO: Replace/update the module that set this DTC. Perform the appropriate VERIFICATION TEST. Vehicle Theft Security Verification Tests