PGM-FI System

DTC Troubleshooting: U0122 (126-4)

DTC U0122:

F-CAN Malfunction (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 the 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 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 Testing and Inspection.�

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 PCM connector A (49P).

10. Check for continuity between PCM connector terminal A48 and VSA modulator-control unit 36P connector terminal No. 14.





Is there continuity?

YES -

Go to step 11.

NO -

Repair an open in the wire between the PCM(A48) and the VSA modulator-control unit, then go to step 12.

11. Check for continuity between PCM connector terminal A49 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 12 and recheck. If DTC U0122 is not indicated after substitution, replace the original VSA modulator-control unit Service and Repair, then go to step 12.

NO -

Repair an open in the wire between the PCM(A49) 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 PCM with the HDS.

15. Do the PCM idle learn procedure 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 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.�