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Pinpoint Test I: U1A00:00

WARNING: This page is about a different car, the 2023 Ford Bronco. However, it is still accessible from the selected car via links, so may be relevant.
  1. Normal Operation and Fault Conditions 

    With the ignition ON, the BCM and the RTM communicate using a LIN. If the RTM is unable to communicate with the BCM using the LIN, the RTM sets a DTC.

    REFER to: Tire Pressure Monitoring System (TPMS) - System Operation and Component Description .

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    RTM U1A00:00 Private Communication Network: No Sub Type Information This DTC sets in continuous memory if the RTM communication bus reset counter reaches zero. This is most likely due to a circuit failure in the LIN, an internal failure of the BCM or an internal failure of the RTM.

    Possible Sources 

    • Fuse
    • Wiring, terminals or connectors
    • RTM
    • BCM

    Visual Inspection and Pre-checks 

    • Make sure BCM fuse 31 (10A) is OK.

    NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

  2. I1 CHECK THE COMMUNICATION NETWORK

    • Ignition ON.

    • Using a diagnostic scan tool, carry out the Network Test.

    Do the RTM and the BCM pass the Network Test? 

    Yes  GO to I2 
    No  DIAGNOSE the RTM or BCM does not respond to the scan tool. REFER to: Controller Area Network (CAN) Module Communications Network .

  3. I2 CHECK THE BCM (BODY CONTROL MODULE) FOR DIAGNOSTIC TROUBLE CODES (DTCS)

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

    Are any Diagnostic Trouble Codes (DTCs) present in the BCM ' 

    Yes  DIAGNOSE the BCM Diagnostic Trouble Codes (DTCs). REFER to: Tire Pressure Monitoring System (TPMS) .
    No  GO to I6 

  4. I3 CHECK THE RTM (RADIO TRANSCEIVER MODULE) VOLTAGE INPUT CIRCUIT FOR AN OPEN

    • Ignition OFF.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C9026 Pin 6
      GFD755274Courtesy of FORD MOTOR COMPANY
      		 C2280C Pin 22

    Is the resistance less than 3 ohms? 

    Yes  GO to I4 
    No  REPAIR the circuit.

  5. I4 CHECK THE RTM (RADIO TRANSCEIVER MODULE) VOLTAGE INPUT CIRCUIT FOR A SHORT TO GROUND

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C9026 Pin 6
      GFD755274Courtesy of FORD MOTOR COMPANY
      		 Ground Pin -

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to I5 
    No  REPAIR the circuit.

  6. I5 CHECK THE RTM (RADIO TRANSCEIVER MODULE) GROUND CIRCUIT FOR AN OPEN

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C9026 Pin 1
      GFD755274Courtesy of FORD MOTOR COMPANY
      		 Ground Pin -

    Is the resistance less than 3 ohms? 

    Yes  GO to I6 
    No  REPAIR the circuit.

  7. I6 CHECK THE LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR A SHORT TO GROUND

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C9026 Pin 2
      GFD755274Courtesy of FORD MOTOR COMPANY
      		 Ground Pin -

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to I7 
    No  REPAIR the circuit.

  8. I7 CHECK THE LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR AN OPEN

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C9026 Pin 2
      GFD755274Courtesy of FORD MOTOR COMPANY
      		 C2280B Pin 26

    Is the resistance less than 3 ohms? 

    Yes  GO to I8 
    No  REPAIR the circuit.

  9. I8 CHECK THE LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR A SHORT TO VOLTAGE

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C9026 Pin 2
      GFD755036Courtesy of FORD MOTOR COMPANY
      		 Ground Pin -

    Is a steady voltage greater than 3 volts present? 

    Yes  REPAIR the circuit.
    No  GO to I9 

  10. I9 VERIFY ALL WIRING CONNECTIONS

    • Ignition OFF.

    • Disconnect all BCM connectors and related in-line connectors.

    • Using a good light source, inspect the BCM connectors RTM connector and related in-line 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

    Are the connectors free of corrosion, damaged pins, bent pins, pushed-out pins and spread terminals? 

    Yes  GO to I10 
    No  REPAIR the connector or terminals. Refer to OEM CONNECTOR REPAIR PROCEDURES for schematic and connector information.

  11. I10 CHECK FOR CORRECT RTM (RADIO TRANSCEIVER MODULE) OPERATION

    • Connect all BCM connectors. Make sure they seat and latch correctly.

    • Connect RTM C9026 and related in-line 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 Technical Service Bulletins (TSBs), 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 RTM. REFER to: Radio Transceiver Module (RTM)
    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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