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HOMESERVICE MANUALSACURA2004TL AUTOMATICREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMPGM-FI SYSTEMDTC TROUBLESHOOTINGDTC U0122: F-CAN MALFUNCTION (VSA-ECM/PCM) (2006 MODEL)
2004 Acura TL Automatic

DTC U0122: F-CAN Malfunction (VSA-ECM/PCM) (2006 Model)

2004 Acura TL AutomaticSECTION DTC U0122: F-CAN Malfunction (VSA-ECM/PCM) (2006 Model)
NOTE:
  • If DTC U0073 is stored at the same time as DTC U0122, troubleshoot DTC U0073 first, then recheck for DTC U0122.
  • Before you troubleshoot, record all freeze data and any on-board snapshot, and review the GENERAL TROUBLESHOOTING INFORMATION .
  1. Turn the ignition switch ON (II).
  2. Clear the DTC with the HDS.
  3. Check for Temporary DTCs or DTCs with the HDS.

    Is DTC U0122 indicated? 

    1. YES  - Go to step  4.
    2. NO  - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the gauge assembly, the VSA modulator-control unit, and the ECM/PCM.
  4. Check for a DTC in the VSA DTCs MENU with the HDS.

    Is VSA DTC 86 indicated? 

    1. YES  - Go to step  5.
    2. NO  - Go to step  8.
  5. Turn the ignition switch OFF.
  6. Disconnect the VSA modulator-control unit 47P connector.
  7. Check for continuity between VSA modulator-control unit 47P connector terminals No. Hand No. 30.
    Fig 1: Checking Continuity Between VSA Modulator-Control Unit 47P Connector Terminals No. Hand No. 30
    G03659440Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Substitute a known-good VSA modulator-control unit, then go to step  15. and recheck. If no DTCs are indicated, replace the original VSA modulator-control unit, then go to step  15.
    2. NO  - Repair open in the wire between the VSA modulator-control unit (No. 14 (No. 30)*) and the ECM/PCM (E15 (E26)*), then go to step  15.
  8. Check for a poor connection at the VSA modulator-control unit 47P connector.

    Are the connections OK? 

    1. YES  - Go to step  9.
    2. NO  - Repair the connection(s), then go to step  15.
  9. Turn the ignition switch OFF.
  10. Disconnect the VSA modulator-control unit 47P connector.
  11. Turn the ignition switch ON (II).
  12. Measure voltage between VSA modulator-control unit 47P connector terminal No. 38 and body ground.
    Fig 2: Measuring Voltage Between VSA Modulator-Control Unit 47P Connector Terminal No. 38 & Body Ground
    G03659441Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step  13.
    2. NO  - Check the No. 21 IG METER (7.5 A) fuse in the under-dash fuse/relay box. If the fuse is OK, repair open in the wire between the No. 21 IG METER (7.5 A) fuse and the VSA modulator-control unit, then go to step  15.
  13. Turn the ignition switch OFF.
  14. Check for continuity between VSA modulator-control unit 47P connector terminal No. 32 and body ground.
    Fig 3: Checking Continuity Between VSA Modulator-Control Unit 47P Connector Terminal No. 32 & Body Ground
    G03659442Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Substitute a known-good VSA modulator-control unit, then go to step  15 and recheck. If no DTCs are indicated, replace the original VSA modulator-control unit, then go to step  15.
    2. NO  - Repair open in the wire between the VSA modulator-control unit and G203, then go to step  15.
  15. Reconnect the VSA modulator-control unit 47P connector.
  16. Turn the ignition switch ON (II).
  17. Reset the ECM/PCM with the HDS.
  18. Do the ECM/PCM IDLE LEARN PROCEDURE .
  19. Check for Temporary DTCs or DTCs with the HDS.

    Are any Temporary DTCs or DTCs Indicated? 

    1. YES  - If DTC U0122 is indicated, check for poor connections or loose terminals at the gauge assembly, the VSA modulator-control unit, and the ECM/PCM, then go to step  1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
    2. NO  - Troubleshooting is complete.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.