Code No. U0001 Bus-off


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, Trouble code diagnosis ).
  • If diagnosis code U0001 is set in ABS-ECU, always diagnose the CAN bus line. If there is any fault in the CAN bus lines, an incorrect diagnosis code may be set. In this case, the set diagnosis code is not highly reliable.
  • Before replacing the ECU, ensure that the communication circuit is normal.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when ABS-ECU has ceased the CAN communication (bus off).

COMMENTS ON TROUBLE SYMPTOM
Malfunction of wiring harness, connector (s), or ABS-ECU may be present.

PROBABLE CAUSES

  • Wiring harness or connector failure of CAN bus line
  • ABS-ECU malfunction

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). On completion, go to Step 3.

STEP 2. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. U0001 set?
Replace the ABS-ECU.
If the trouble symptom is resolved, an intermittent malfunction such as poorly engaged connector(s) or wiring harness is suspected (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 3. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. U0001 set?
Return to Step 1.
This diagnosis is complete.