Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Acura >> 2009 >> TSX Standard >> 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 Temporary DTCs or 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 Temporary DTCs or 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 DLC circuit troubleshooting (see DLC CIRCUIT TROUBLESHOOTING )

  6. Turn the ignition switch to LOCK (0)
  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 A3 and VSA modulator-control unit 47P connector terminal No 12
    Fig 1: Checking Continuity Between ECM/PCM Connector Terminal A3 And VSA Modulator-Control Unit 47P Connector Terminal No 12
    G05992293Courtesy 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 47P connector terminal No 13
    Fig 2: Checking Continuity Between ECM/PCM Connector Terminal A4 And VSA Modulator-Control Unit 47P Connector Terminal No 13
    G05992294Courtesy 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 Temporary DTCs or DTCs with the HDS

    Is DTC U0122 indicated? 

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

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

scientia non olet · About Mike's Workshop Manuals