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PINPOINT TEST L: No UNIVERSAL ASYNCHRONOUS RECEIVER-TRANSMITTER (UART) BASED PROTOCOL (UBP) COMMUNICATIONS NETWORK COMMUNICATION

WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.
NOTE: Since the instrument cluster is directly wired to the restraint control module (RCM), depower of the supplemental restraint system (SRS) is required when disconnecting the instrument cluster C220a or C220b. When Key ON occurs to measure voltage, diagnostic trouble codes (DTCs) may be stored in the RCM. These DTCs should be cleared when network diagnostics are completed.
NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer. For additional SRS information, refer to SUPPLEMENTAL RESTRAINT SYSTEM .
  1. L1 CHECK THE UBP CIRCUIT BETWEEN THE INSTRUMENT CLUSTER AND THE DLC FOR AN OPEN 
    • Key in OFF position.
    • Depower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
    • Disconnect: Instrument Cluster C220b.
    • Measure the resistance between the DLC C251-3, circuit 693 (OG), harness side and the instrument cluster C220b-7, circuit 693 (OG), harness side.
      Fig 1: Measuring Resistance Between DLC And Instrument Cluster
      G03945822Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to L2.
    • No  : REPAIR the circuit.

      CONNECT the instrument cluster C220b.

      REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .

      CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.

  2. L2 CHECK THE UBP COMMUNICATIONS NETWORK WITH THE INSTRUMENT CLUSTER C220B DISCONNECTED 
    • Key in ON position.
    • Enter the following diagnostic mode on the diagnostic tool: Diagnostic Tool Data Link Test.
    • Does the diagnostic tool indicate system passed? 
  3. L3 CHECK THE UBP CIRCUIT BETWEEN THE VEHICLE SECURITY MODULE AND THE DLC FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: Vehicle Security Module C3203f.
    • Measure the resistance between the vehicle security module C3203f-5, circuit 693 (OG), harness side and the DLC C251-3, circuit 693 (OG), harness side.
      Fig 2: Measuring Resistance Between Vehicle Security Module And DLC
      G03945770Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to L4.
    • No  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
  4. L4 CHECK THE UBP COMMUNICATIONS NETWORK WITH THE VEHICLE SECURITY MODULE C3203F DISCONNECTED 
    • Key in OFF position.
    • Enter the following diagnostic mode on the diagnostic tool: Diagnostic Tool Data Link Test.
    • Does the diagnostic tool indicate system passed? 
    • Yes  : GO to  L10.
    • No  : If equipped with DSM, GO to L5. All others, GO to  L7.
  5. L5 CHECK THE UBP CIRCUIT BETWEEN THE DSM AND THE DLC FOR AN OPEN 
    • Key in OFF position.
    • Connect: Vehicle Security Module C3203f.
    • Disconnect: DSM C341g.
    • Measure the resistance between the DSM C341g-2, circuit 693 (OG), harness side and the DLC C251-3, circuit 693 (OG), harness side.
      Fig 3: Measuring Resistance Between DSM And DLC
      G03945824Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to L6.
    • No  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
  6. L6 CHECK THE UBP COMMUNICATIONS NETWORK WITH THE DSM C341G DISCONNECTED 
    • Key in ON position.
    • Enter the following diagnostic mode on the diagnostic tool: Diagnostic Tool Data Link Test.
    • Does the diagnostic tool indicate system passed? 
    • Yes  : GO to  L11.
    • No  : GO to L7.
  7. L7 CHECK THE UBP COMMUNICATIONS NETWORK CIRCUIT 693 (OG) FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Depower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
    • Disconnect: Vehicle Security Module C3203f, Instrument Cluster C220b, and DSM C341g (if equipped).
    • Measure the resistance between the DLC C251-3, circuit 693 (OG), harness side and ground.
      Fig 4: Measuring Resistance Between DLC C251-3 And Ground
      G03945825Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10,000 ohms? 
    • Yes  : GO to L8.
    • No  : REPAIR the circuit.

      CONNECT the UBP network module electrical connectors. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .

      CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.

  8. L8 CHECK THE UBP COMMUNICATIONS NETWORK CIRCUIT 693 (OG) FOR A SHORT TO VOLTAGE 
    • Key in ON position.
    • Measure the voltage between the DLC C251-3, circuit 693 (OG), harness side and ground.
      Fig 5: Measuring Voltage Between DLC And Ground
      G03945826Courtesy of FORD MOTOR CO.
    • Is any voltage indicated? 
    • Yes  : REPAIR the circuit.

      CONNECT the UBP network module electrical connectors. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .

    • CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
    • No  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

      CONNECT the UBP network module electrical connectors. REPOWER the SRS. REFER to SUPPLEMENTAL RESTRAINT SYSTEM .

      CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.

  9. L9 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION 
    • Disconnect all the instrument cluster connectors.
    • Check for:
      • corrosion
      • push-out pins
    • Connect all the instrument cluster connectors and make sure they seat correctly.
    • Repower the SRS. Refer to SUPPLEMENTAL RESTRAINT SYSTEM .
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    • Yes  : INSTALL a new instrument cluster. REFER to INSTRUMENT CLUSTER . CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
    • No  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
  10. L10 CHECK FOR CORRECT VEHICLE SECURITY MODULE OPERATION 
    • Disconnect all the vehicle security module connectors.
    • Check for:
      • corrosion
      • push-out pins
    • Connect all the vehicle security module connectors and make sure they seat correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    • Yes  : INSTALL a new vehicle security module. REFER to MULTIFUNCTION ELECTRONIC MODULES . CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
    • No  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
  11. L11 CHECK FOR CORRECT DSM OPERATION 
    • Disconnect all the DSM connectors.
    • Check for:
      • corrosion
      • push-out pins
    • Connect all the DSM connectors and make sure they seat correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    • Yes  : INSTALL a new DSM. REFER to MULTIFUNCTION ELECTRONIC MODULES . CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
    • No  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
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