LEMON Manuals: Even more car manuals for everyone
Home >> Ford >> 2022 >> Mustang Mach 1 Premium, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 34 (Automatic Transmission External Controls - 7-Speed Automatic Transmission - Tr9070) >> Diagnosis And Testing >> External Controls >> Pinpoint Tests >> Pinpoint Test F: U0121

Pinpoint Test F: U0121

WARNING: This page is about a different variant/trim than selected.
  1. Refer to TRANSMISSION CONTROLS - TR9070 for schematic and connector information.

    Normal Operation and Fault Conditions 

    The GSM and ABS module communicate through messages sent over HS-CAN. The GSM will set a DTC when it has not received messages from the ABS module for more than 5 seconds.

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    GSM U0121:00 Lost Communication With Anti-Lock Brake System (ABS) Control Module 'A': No Sub Type Information Sets in continuous memory in the GSM if data messages received from the ABS are missing for 5 seconds or longer.

    Possible Sources 

    • Communication concern
    • Incorrect PMI
    • Connectors damaged or pushed-out terminals, corrosion, loose wires and missing or damaged seals
    • ABS module

  2. F1 VERIFY THE SCAN TOOL COMMUNICATES WITH THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE

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

    Did the ABS module complete the self-test? 

    Yes  GO to  F2
    No  RESOLVE the ABS module does not respond to the diagnostic scan tool concern. REFER to: Communications Network .

  3. F2 CHECK THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE FOR DIAGNOSTIC TROUBLE CODES (DTCS)

    • Using a diagnostic scan tool, retrieve all diagnostic trouble codes (DTCs) from the ABS module self-test.

    Are any diagnostic trouble codes (DTCs) present in the ABS module? 

    Yes  RESOLVE those diagnostic trouble codes (DTCs) first. REFER to: Anti-Lock Brake System (ABS) and Stability Control .
    No  GO to  F3

  4. F3 CHECK THE GSM (GEAR SHIFT MODULE) FOR DIAGNOSTIC TROUBLE CODES (DTCS)

    • Using a diagnostic scan tool, CARRY OUT the GSM self-test.

    Are any non-network diagnostic trouble codes (DTCs) present in the GSM? 

    Yes  RESOLVE all non-network diagnostic trouble codes (DTCs) first. REFER to Diagnostic Trouble Code (DTC) Chart 
    No  GO to  F4

  5. F4 CHECK THE GWM (GATEWAY MODULE A) DIAGNOSTIC TROUBLE CODES (DTCS)

    • Using a diagnostic scan tool, CARRY OUT the GWM self-test.

    Are any diagnostic trouble codes (DTCs) present in the GWM? 

    Yes  REFER to: Communications Network .
    No  GO to  F5

  6. F5 RECHECK THE GSM (GEAR SHIFT MODULE) FOR DTC (DIAGNOSTIC TROUBLE CODE) U0121

    • Using a diagnostic scan tool, clear all diagnostic trouble codes (DTCs) from the GSM.

    • Road test the vehicle.

    • Using a diagnostic scan tool, CARRY OUT the GSM self-test.

    Is DTC U0121 still present? 

    Yes  GO to  F6
    No  The system is operating correctly at this time. The DTC may have set due to high network traffic or an intermittent fault condition.

  7. F6 CHECK FOR OTHER CAUSES OF NETWORK COMMUNICATION CONCERNS

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

    • CHECK the vehicle service history for recent service actions related to the ABS module or the GSM. If recent service history is found:

      • verify correct replacement module was installed

        • HVBOM may be used to verify correct part application

      • verify the configuration of replacement module was correct

        • re-configure module using as-built data if prior configuration is suspect

      • verify the module was not obtained from a like vehicle and installed into customer vehicle

        • return the swapped module to source vehicle and obtain new replacement module

    Were any causes of a communication concern found in the vehicle service history? 

    Yes  PROGRAM or INSTALL a new module as necessary.
    No  GO to  F7

  8. F7 CHECK FOR CORRECT ABS (ANTI-LOCK BRAKE SYSTEM) OPERATION

    • Ignition OFF.

    • Disconnect the ABS module and all related in-line electrical connectors.

    • Using a good light source, inspect all  disconnected electrical connectors for the following:

      • corrosion - install new connector or terminal and clean the module pins
      • damaged or bent pins - install new terminals or pins
      • pushed-out pins - install new pins as necessary
      • spread terminals - install new terminals as necessary

    • Reconnect the ABS and all related in-line electrical 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 TSB. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no TSB addresses this concern, INSTALL a new ABS. 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.
scientia non olet · About LEMON Manuals