VSA Modulator Control Unit

Control System DTCs

DTC Troubleshooting: U0122

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 How To Troubleshoot The Fuel And Emissions Systems.

1. DTC check:

DTC check
-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 ECM/PCM.
-NO- Go to step 2.

2. Problem verification:

Problem verification
-1. Clear the DTC with the HDS.

-2. Check for Pending or Confirmed DTCs with the HDS.

Is DTC U0122 indicated?
-YES- The failure is duplicated. Go to step 3.
-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.

3. VSA system check:

VSA system check
-1. Check for communication to the VSA system with the HDS.

Does the HDS communicate with the VSA modulator-control unit?
-YES- Go to step 4.
-NO- Go to the symptom troubleshooting for ABS indicator, brake system indicator, and VSA indicator do not go off ABS Indicator, Brake System Indicator, and VSA Indicator Do Not Go Off.

4. Open wire check (F_CAN-H line):

Open wire check (F_CAN-H line)
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connectors.





-4. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The F_CAN-H wire is OK. Go to step 5.
-NO- Repair an open in the F_CAN-H wire between the ECM/PCM (A3) and the VSA modulator-control unit, then do the repair verification.

5. Open wire check (F_CAN-L line):

Open wire check (F_CAN-L line)
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The F_CAN-L wire is OK. Update the VSA modulator-control unit Programming and Relearning if it does not have the latest software, then do the repair verification. If DTC U0122 is indicated after updated, replace the original VSA modulator-control unit Service and Repair, then do the repair verification.
-NO- Repair an open in the F_CAN-L wire between the ECM/PCM (A4) and the VSA modulator-control unit, then do the repair verification.

Repair verification:

-1. Turn the ignition switch to LOCK (0).

-2. Reconnect all connectors.

-3. Turn the ignition switch to ON (II).

-4. Reset the ECM/PCM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-5. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.

-6. 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 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.