DTC Troubleshooting: U0073 (126)

DTC U0073:  F-CAN Malfunction (Bus-Off)

1.Turn the ignition switch ON (II).

2.Clear the DTC with the HDS.

3.Start the engine.

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

Is DTC U0073 indicated?


YES - Go to 5.


NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the VSA modulator-control unit or the ECM.n


5.Turn the ignition switch OFF, and wait 10 seconds.

6.Disconnect the VSA modulator-control unit 46P connector and yawrate/lateral acceleration sensor 4P connector.

7.Turn the ignition switch ON (II).

8.Measure voltage between VSA modulator-control unit 46P connector terminals No. 38, No. 39 and body ground individually.

 

Is there battery voltage?


YES - Go to 9.


NO - Go to 12.


9.Turn the ignition switch OFF, and wait 10 seconds.

10.Disconnect ECM connector No. 4 (40P).

11.Measure voltage between VSA modulator-control unit 46P connector terminals No. 38, No. 39 and body ground individually.

 

Is there battery voltage?


YES - Repair short to power in the wire between ECM connector No. 4 terminal No. 40 (CANH line), terminal No. 30 (CANL line) and VSA modulator-control unit 46P connector, then go to 19.


NO - Substitute a known good ECM, then go to 19.


12.Turn the ignition switch OFF and wait 10 seconds.

13.Check for continuity between VSA modulator-control unit 46P connector terminals No. 38, No. 39 and body ground individually.

 

Is there continuity?


YES - Go to 14.


NO - Go to 16.

14.Disconnect ECM connector No. 4 (40P).

15.Check for continuity between VSA modulator-control unit 46P connector terminals No. 38, No. 39 and body ground individually.

 

Is there continuity?


YES - Repair short to ground in the wire between ECM connector No. 4 terminal No. 40 (CANH line), terminal No. 30 (CANL line) and VSA modulator-control unit 46P connector, then go to 19.


NO - Substitute a known good ECM, then go to 19.

16.Check for resistance between VSA modulator-control unit 46P connector terminals No. 38 and No. 39.

 

Is there about 120±12 W?


YES - Substitute a known good VSA modulator-control unit, and the yawrate/lateral acceleration sensor unit one at a time until the DTCs are no longer present, then replace the control module that made the DTCs go away. If the symptom does not go away, substitute a known good ECM, then go to 19.


NO - Go to 17.

17.Disconnect ECM connector No. 4 (40P).

18.Check for continuity between VSA modulator-control unit 46P connector terminals No. 38 and No. 39.

 

Is there continuity?


YES - Repair short in the wire between ECM connector No. 4 terminal No. 40 (CANH line), terminal No. 30 (CANL line) and VSA modulator-control unit connector, then go to 19.


NO - Substitute a known good ECM, then go to 19.

19.Turn the ignition switch OFF, and wait 10 seconds.

20.Reconnect all connectors.

21.Turn the ignition switch ON (II).

22.Reset the ECM with the HDS.

23.Do the ETCS learn procedure.

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

Are any Temporary DTCs or DTCs indicated?


YES - If DTC U0073 is indicated, check for poor connections and loose terminals at the VSA modulator-control unit and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - Troubleshooting is complete. If the ECM was substituted, replace the original ECM.n