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Home >> Honda >> 2012 >> Accord SE >> Repair and Diagnosis >> Engine Performance >> System >> PGM-FI System (4-CYL) >> DTC Troubleshooting >> DTC U0122: F-CAN Malfunction (ECM/PCM-VSA Modulator-Control Unit)

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).
  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: F-CAN MALFUNCTION (BUS-OFF (ECM/PCM))  ).

    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 SYMPTOM TROUBLESHOOTING ).

  6. Turn the ignition switch to LOCK (0).
  7. Jump the SCS line with the HDS.
  8. Disconnect the VSA modulator-control unit 36P connector.
  9. Disconnect ECM/PCM connector A (49P).
  10. Check for continuity between ECM/PCM connector terminal A3 and VSA modulator-control unit 36P connector terminal No. 14.
    Fig 1: Checking Continuity Between ECM/PCM Connector Terminal A3 And VSA Modulator-Control Unit 36P Connector Terminal No. 14
    G07341493Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Go to step 11.

    NO  -Repair open in the wire between the ECM/PCM (A3) and the VSA modulator-control unit, then go to step  12.

  11. Check for continuity between ECM/PCM connector terminal A4 and VSA modulator-control unit 36P connector terminal No. 1.
    Fig 2: Checking Continuity Between ECM/PCM Connector Terminal A4 And VSA Modulator-Control Unit 36P Connector Terminal No. 1
    G07341494Courtesy 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 (A4) and the VSA modulator-control unit, then go to step 12.

  12. Reconnect all connectors.
  13. Turn the ignition switch to ON (II).
  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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