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Pinpoint Test I: DTC U0100, U0401

  1. Refer to MODULE COMMUNICATIONS NETWORK for schematic and connector information. Refer to TRANSMISSION CONTROLS for schematic and connector information.

    Normal Operation and Fault Conditions 

    The GSM and PCM communicate over HS-CAN1 and HS-CAN2 through the GWM. They also communicate over a dedicated Transmission CAN.

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    GSM U0100:00 Lost Communication With ECM/PCM 'A': No Sub Type Information This DTC sets if the GSM does not receive some or all of an expected message from the PCM over HS-CAN2.
    GSM U0100:87 Lost Communication With ECM/PCM 'A': Missing Message This DTC sets if the GSM does not receive some or all of an expected message from the PCM over CAN.
    GSM U0401:00 Invalid Data Received from ECM/PCM A: No Sub Type Information This DTC sets if the GSM detects invalid data from the PCM.

    Possible Sources 

    • Communication concern
    • PCM
    • GSM

  2. I1 VERIFY THE SCAN TOOL COMMUNICATES WITH THE PCM (POWERTRAIN CONTROL MODULE)

    • Using a diagnostic scan tool, carry out the PCM self-test.

    Did the PCM complete the self-test? 

    Yes  GO to  I2
    No  To diagnose the module does not respond to the scan tool, REFER to: Controller Area Network (CAN) Module Communications Network .

  3. I2 RETRIEVE THE DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE PCM (POWERTRAIN CONTROL MODULE)

    • Using a diagnostic scan tool, retrieve all diagnostic trouble codes from the PCM self-test.

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

    Yes  RESOLVE those DTCs first. REFER to: Electronic Engine Controls .
    No  GO to  I3

  4. I3 CHECK FOR GSM (GEAR SHIFT MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)

    NOTE: If a GSM self-test is carried out, the driver door must be fully closed and locked. A false P166B DTC may set if the driver door is not fully closed and locked.

    • Using a diagnostic scan tool, carry out the GSM self-test.

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

    Yes  RESOLVE all non-network diagnostic trouble codes (DTCs) first. REFER to Diagnostic Trouble Code (DTC) Chart  .
    No  GO to  I4

  5. I4 CHECK FOR 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  RESOLVE all GWM diagnostic trouble codes (DTCs) first. REFER to: Controller Area Network (CAN) Module Communications Network .
    No  GO to  I5

  6. I5 CHECK FOR DTC (DIAGNOSTIC TROUBLE CODE) U0100, U0401 SET IN OTHER MODULES

    • Using a diagnostic scan tool, retrieve all continuous memory diagnostic trouble codes (CMDTCs) from all modules.

    Is DTC U0100 and/or U0401 present in other modules? 

    Yes  CHECK OASIS for any applicable service articles: TSB, GSB (general service bulletin), SSM (special service message) or FSA (Field Service Action). 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 PCM. Refer to POWERTRAIN CONTROL MODULE (PCM) . After installing a new PCM, CARRY OUT the transmission strategy download. REFER to: Transmission Strategy Download .
    No  GO to  I6

  7. I6 PROGRAM THE PCM (POWERTRAIN CONTROL MODULE) WITH THE LATEST CALIBRATION

    NOTE: If a GSM self-test is carried out, the driver door must be fully closed and locked. A false P166B DTC may set if the driver door is not fully closed and locked.

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

    • Program the PCM with the latest calibration.

    • Road test the vehicle.

    • Using a diagnostic scan tool, carry out the GSM self-test.

    Is DTC U0100, U0100:87 and/or U0401 still present? 

    Yes  For DTC U0100:00 and/or U0401, GO to  I7 For DTC U0100:87, GO to  I9
    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.

  8. I7 CHECK THE HS-CAN2 (HIGH-SPEED CONTROLLER AREA NETWORK 2) CIRCUITS FOR AN OPEN

    • Ignition OFF.

    • Disconnect PCM C1915B .

    • Disconnect GWM C4391A .

    • Inspect the connectors for damaged or pushed-out terminals.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2532-2
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 C4391A-21
      C2532-3
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 C4391A-8
      C175B-33
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 C4391A-17
      C175B-48
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 C4391A-4

    Are the resistances less than 3 ohms? 

    Yes  GO to  I8
    No  REPAIR the circuit.

  9. I8 CHECK THE HS-CAN2 (HIGH-SPEED CONTROLLER AREA NETWORK 2) CIRCUITS FOR A SHORT TO GROUND

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C4391A-4
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 Ground
      C4391A-8
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 Ground
      C4391A-17
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 Ground
      C4391A-21
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the resistances greater than 10, 000 ohms? 

    Yes  GO to  I11
    No  REPAIR the circuit.

  10. I9 CHECK THE TRANS CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR AN OPEN

    • Ignition OFF.

    • Inspect the connectors for damaged or pushed-out terminals.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2532-13
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 C175T-8
      C2532-14
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 C175T-23

    Are the resistances less than 3 ohms? 

    Yes  GO to  I10
    No  REPAIR the circuit.

  11. I10 CHECK THE TRANS CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR A SHORT TO GROUND

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2532-13
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 Ground
      C2532-14
      GFD706634Courtesy of FORD MOTOR COMPANY
      		 Ground

    Are the resistances greater than 10, 000 ohms? 

    Yes  GO to  I11
    No  REPAIR the circuit.

  12. I11 CHECK FOR CORRECT GSM (GEAR SHIFT MODULE) OPERATION

    • Ignition OFF.

    • Disconnect and inspect GSM C2532 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 GSM C2532 and all related in-line electrical connectors. Make sure they seat and latch correctly.

    • Using the diagnostic scan tool, clear all DTCs.

    • Carry out the GSM self-test.

    Are diagnostic trouble codes (DTCs) U0100 and/or U0401 still present? 

    Yes  CHECK OASIS for any applicable service articles: TSB, GSB (general service bulletin), SSM (special service message) or FSA (Field Service Action). 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 GSM. REFER to: Gear Shift Module (GSM) .
    No  The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.
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