EPS Control Unit

Control System DTCs

DTC Troubleshooting: U0131

DTC U0131 : F-CAN Malfunction (ECM-EPS 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 U0028 and U0131 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 U0131 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 EPS control unit and the ECM.

3. EPS system check:

EPS system check
-1. Check that the HDS communicates with the EPS system.

Does the HDS communicate with the EPS control unit?
-YES- Go to step 4.
-NO- Go to the symptom troubleshooting for an EPS indicator does not go off, and no DTCs are stored EPS Indicator Does Not Go Off, And No DTCs Are Stored.

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 (A3) and the EPS 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 EPS control unit Programming and Relearning if it does not have the latest software, or substitute a known-good EPS control unit Service and Repair, then do the repair verification. If DTC U0131 is not indicated after substitution, replace the original EPS control unit Service and Repair, then do the repair verification.
-NO- Repair an open in the F_CAN-L wire between the ECM (A4) and the EPS control unit, then do the repair verification.

Repair verification:

-1. Reconnect all connectors.

-2. Turn the ignition switch to ON (II).

-3. Reset the ECM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-4. Do the ECM idle learn procedure ECM/PCM Idle Learn Procedure.

-5. Check for Pending or Confirmed DTCs with the HDS.

Is DTC U0131 indicated?
-YES- Check for poor connections or loose terminals at the EPS control unit and the ECM, 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.