PGM-FI System

DTC Troubleshooting: U0122 (PGM-FI System)

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. Initial Inspection and Diagnostic Overview

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 troubleshooting for DTC U0029. 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. Turn the ignition switch to ON (II), and watch the ABS indicator, the brake system indicator, and the VSA indicator.

Do the indicators come on and go off?
YES - Go to step 6.

NO - Go to symptom troubleshooting for ABS indicator, brake system indicator, and VSA indicator do not go off. Symptom Troubleshooting


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

Does the HDS communicate with the VSA modulator-control unit?
YES - Go to step 7.

NO - Go to the DLC circuit troubleshooting. Testing and Inspection


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

8. Jump the SCS line with the HDS.

9. Disconnect the VSA modulator-control unit 36P connector.

10. Disconnect ECM/PCM connector A (49P).

11. Check for continuity between ECM/PCM connector terminal A3 and VSA modulator-control unit 36P connector terminal No. 14.

Is there continuity?
YES - Go to step 12.

NO - Repair open in the wire between the ECM/PCM (A3) and the VSA modulator-control unit, then go to step 13.






12. Check for continuity between ECM/PCM connector terminal A4 and VSA modulator-control unit 36P connector terminal No. 1.

Is there continuity?
YES - Update the VSA modulator-control unit if it does not have the latest software, Testing and Inspection or substitute a known-good VSA modulator-control unit, Service and Repair then go to step 13 and recheck. If DTC U0122 is not indicated after substitution, replace the original VSA modulator-control unit, Service and Repair then go to step 13.

NO - Repair open in the wire between the ECM/PCM (A4) 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/PCM with the HDS.

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

17. 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 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.