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Home >> Chrysler >> 2007 >> 300 Base >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Electronic Control Modules - Electrical Diagnostics >> Electronic Control Modules - Electrical Diagnostics >> DTC Troubleshooting >> U0121-Lost Communication With Anti-Lock Brake Module >> Diagnostic Test

Diagnostic Test

  1. 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.

    Is this DTC active? 

    Yes 

    1. Go To  2).

    No 

    1. Refer to the Stored Lost Communication test procedure. See *STORED LOST COMMUNICATION DTCS .
    2. Perform BODY VERIFICATION TEST - VER 1 .
  2. 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.

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

    Yes 

    1. Diagnose and repair the DTC. Refer to DIAGNOSTIC CODE INDEX .
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To  3).
  3. 3) VERIFY THAT THE ABS IS ACTIVE ON THE BUS 

    Turn the ignition on.

    With the scan tool, select ECU View.

    Verify that the ABS is active on the bus.

    Is the ABS active on the bus? 

    Yes 

    1. Go To  4).

    No 

    1. Refer to CHECKING FOR INTERMITTENT DTC, COMPONENT & SYSTEM CHECKS, SYMPTOM TESTS for a no response test procedure.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  4. 4) CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS 

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

    Is there more than one module with active DTCs "Logged Against" the ABS? 

    Yes 

    1. Replace/update the Antilock Brake Module in accordance with the service information.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Replace/update the module that set this DTC in accordance with the service information
    2. Perform BODY VERIFICATION TEST - VER 1 .