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 (see GENERAL TROUBLESHOOTING INFORMATION ).

Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
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.
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.
Turn the ignition switch to LOCK (0).
Jump the SCS line with the HDS.
Disconnect the VSA modulator-control unit 47P connector (see VSA MODULATOR-CONTROL UNIT REMOVAL AND INSTALLATION ).
Disconnect ECM connector E (31P).
Connect VSA modulator-control unit 47P connector terminal No. 11 to body ground with a jumper wire.

Fig 1: Connecting VSA Modulator-Control Unit 47P Connector Terminal No. 11 To Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between ECM connector terminal E11 and body ground.

Fig 2: Checking Continuity Between ECM Connector Terminal E11 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

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

Fig 3: Connecting VSA Modulator-Control Unit Connector Terminal No. 15 To Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between ECM connector terminal E24 and body ground.

Fig 4: Checking Continuity Between ECM Connector Terminal E24 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Substitute a known-good VSA modulator-control unit (see VSA MODULATOR-CONTROL UNIT REMOVAL AND INSTALLATION ), then go to step 13 and recheck. If DTC U0122 is not indicated, replace the original VSA modulator-control unit (see VSA MODULATOR-CONTROL UNIT REMOVAL AND INSTALLATION ), 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.
Reconnect all connectors.
Turn the ignition switch to ON (II).
Reset the ECM with the HDS.
Do the ECM idle learn procedure (see ECM IDLE LEARN PROCEDURE ).
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.