DTC Troubleshooting

DTC Troubleshooting: U0122

DTC U0122: F-CAN Malfunction (ECM-VSA Modulator-Control Unit)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Initial Inspection and Diagnostic Overview

1. Turn the ignition switch to ON (II).

2. Clear the DTC with the HDS.

3. Check for Temporary DTCs or DTCs with the HDS.

Is DTC U0122 indicated?
YES - Go to step 4.

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.


4. Check for DTCs in the DTCs MENU with the HDS.

Is VSA DTC 86 indicated?
YES - Go to step 5.

NO - Go to step 13.


5. Turn the ignition switch to LOCK (0).

6. Jump the SCS line with the HDS.

7. Disconnect the VSA modulator-control unit 47P connector. Service and Repair

8. Disconnect ECM connector E (31P).

9. Connect VSA modulator-control unit 47P connector terminal No. 11 to body ground with a jumper wire.






10. Check for continuity between ECM connector terminal E11 and body ground.

Is there continuity?
YES - Go to step 11.

NO - Repair open in the wire between the ECM (E11) and the VSA modulator-control unit, then go to step 13.






11. Connect VSA modulator-control unit connector terminal No. 15 to body ground with a jumper wire.






12. Check for continuity between ECM connector terminal E24 and body ground.

Is there continuity?
YES - Substitute a known-good VSA modulator-control unit, Service and Repair then go to step 13 and recheck. If DTC U0122 is not indicated, replace the original VSA modulator-control unit, Service and Repair then go to step 13.

NO - Repair open in the wire between the ECM (E24) and the VSA modulator-control unit, then go to step 13.






13. Reconnect all connectors.

14. Turn the ignition switch to ON (II).

15. Reset the ECM with the HDS.

16. Do the ECM idle learn procedure. ECM Idle Learn Procedure

17. 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-control unit and the ECM, 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.