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Home >> Acura >> 2012 >> TL Base >> Repair and Diagnosis >> Engine Performance >> System >> PGM-FI System >> DTC Troubleshooting >> DTC U0122: F-CAN Malfunction (ECM/PCM-VSA Modulator-Control Unit)
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DTC U0122: F-CAN Malfunction (ECM/PCM-VSA Modulator-Control Unit)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
  1. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
  2. Check for Pending or Confirmed DTCs with the HDS.

    Are DTC U0029 and U0122 indicated at the same time? 

    YES  - Go to the troubleshooting for DTC U0029 (see DTC U0029 ). ■

    NO  - Go to step 3.

  3. Clear the DTC with the HDS.
  4. Check for Pending or Confirmed DTCs with the HDS.

    Is DTC U0122 indicated? 

    YES  - Go to step 5.

    NO  - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the VSA modulator-control unit and the ECM/PCM. ■

  5. Check for communication to the VSA system with the HDS.

    Does the HDS communicate with the VSA modulator-control unit? 

    YES  - Go to step 6.

    NO  - Go to the symptom troubleshooting for ABS indicator, brake system indicator, and VSA indicator do not go off (see ABS INDICATOR, BRAKE SYSTEM INDICATOR, AND VSA INDICATOR DO NOT GO OFF ). ■

  6. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
  7. Jump the SCS line with the HDS.
  8. Disconnect the VSA modulator-control unit 47P connector.
  9. Disconnect ECM/PCM connector A (49P).
  10. Check for continuity between ECM/PCM connector terminal A48 and VSA modulator-control unit 47P connector terminal No. 12.
    Fig 1: Checking Continuity Between ECM/PCM Connector Terminal A48 And VSA Modulator-Control Unit 47P Connector
    G08069529Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step 11.

    NO  - Repair open in the wire between the ECM/PCM (A48) and the VSA modulator-control unit, then go to step  12.

  11. Check for continuity between ECM/PCM connector terminal A49 and VSA modulator-control unit 47P connector terminal No. 13.
    Fig 2: Checking Continuity Between ECM/PCM Connector Terminal A49 And VSA Modulator-Control Unit 47P Connector
    G08069530Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Update the VSA modulator-control unit if it does not have the latest software (see VSA MODULATOR-CONTROL UNIT UPDATE ), or substitute a known-good VSA modulator-control unit (see VSA MODULATOR-CONTROL UNIT REMOVAL AND INSTALLATION ), then go to step 12 and recheck. If DTC U0122 is not indicated after substitution, replace the original VSA modulator-control unit (see VSA MODULATOR-CONTROL UNIT REMOVAL AND INSTALLATION ), then go to step 12.

    NO  - Repair open in the wire between the ECM/PCM (A49) and the VSA modulator-control unit, then go to step 12.

  12. Reconnect all connectors.
  13. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
  14. Reset the ECM/PCM with the HDS.
  15. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
  16. Check for Pending or Confirmed DTCs with the HDS.

    Is DTC U0122 indicated? 

    YES  - Check for poor connections or loose terminals at the VSA modulator-control unit and the ECM/PCM, then go to step  1.

    NO  - Troubleshooting is complete. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting. ■

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