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Pinpoint Test G: U0121:00

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
  1. Refer to MODULE COMMUNICATIONS NETWORK for schematic and connector information.

    Normal Operation and Fault Conditions 

    REFER to: Interior Camera System - System Operation and Component Description .

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    CMR U0121:00 Lost Communication With Anti-Lock Brake System (ABS) Control Module "A": No Sub Type Information A continuous memory DTC that sets in the driver status monitor camera module if messages from the ABS module over the FD-CAN are missing.

    Possible Sources 

    • Communication network concern
    • Battery voltage concern
    • ABS module
    • Driver status monitor camera module (CMR)

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

  3. G1 CHECK THE COMMUNICATION NETWORK

    • Ignition ON.

    • Connect the diagnostic tool.

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

    Can a vehicle session be established? 

    Yes  GO to  G2
    No 

  4. G2 CONFIRM THE DTC RESETS

    • Using a diagnostic scan tool, clear the Diagnostic Trouble Codes (DTCs).

    • Ignition OFF.

    • Ignition ON.

    • Wait 10 seconds.

    • Using a diagnostic scan tool, check the CMR Continuous Memory Diagnostic Trouble Codes (CMDTCs).

    Is DTC U0121:00 still present? 

    Yes  GO to  G3
    No  The system is operating correctly at this time. The DTC may have been falsely set by the driver status monitor camera module causing the signal to momentarily stop and set the DTC.

  5. G3 RETRIEVE THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE DTCS

    • Using a diagnostic scan tool, perform the ABS module self-test.

    Are any non-network ABS module Diagnostic Trouble Codes (DTCs) present? 

    Yes  REFER to: Anti-Lock Brake System (ABS) and Stability Control .
    No  GO to  G4

  6. G4 RETRIEVE THE DRIVER STATUS MONITOR CAMERA MODULE CMDTCS

    • Using a diagnostic scan tool, clear the Diagnostic Trouble Codes (DTCs).

    • Wait 10 seconds.

    • Using a diagnostic scan tool, check the CMR CMDTCs.

    Are any non-network CMR Diagnostic Trouble Codes (DTCs) recorded? 

    Yes  REFER to the Diagnostic Trouble Code (DTC) Chart 
    No  GO to  G5

  7. G5 CHECK FOR DTC (DIAGNOSTIC TROUBLE CODE) U0121:00 SET IN OTHER MODULES

    • Using a diagnostic scan tool, clear the DTCs.

    • Ignition OFF.

    • Wait 10 seconds.

    • Ignition ON.

    • Using a diagnostic scan tool, retrieve all  CMDTCs.

    Is DTC U0121:00 set in other modules? 

    Yes  GO to  G6
    No  GO to  G7

  8. G6 CHECK FOR CORRECT ABS (ANTI-LOCK BRAKE SYSTEM) MODULE OPERATION

    • Ignition OFF.

    • Disconnect and inspect the ABS connector.

    • Repair:

      • corrosion (install new connector or terminals - clean module pins)
      • damaged or bent pins - install new terminals/pins
      • pushed-out pins - install new pins as necessary

    • Reconnect the ABS module connector. Make sure it seats and latches correctly.

    • Operate the system and determine if the concern is still present.

    Is the concern still present? 

    Yes  CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new ABS module. REFER to: Anti-Lock Brake System (ABS) Module .
    No  The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.

  9. G7 CHECK FOR CORRECT DRIVER STATUS MONITOR CAMERA MODULE OPERATION

    • Ignition OFF.

    • Disconnect and inspect the driver status monitor camera module connectors.

    • Repair:

      • corrosion (install new connector or terminals - clean module pins)
      • damaged or bent pins - install new terminals/pins
      • pushed-out pins - install new pins as necessary

    • Reconnect the driver status monitor camera module connectors. Make sure they seat and latch correctly.

    • Operate the system and determine if the concern is still present.

    Is the concern still present? 

    Yes  CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new driver status monitor camera module. REFER to: Driver Status Monitor Camera Module [CMR] .
    No  The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.
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