Code No. U0001: Bus Off



caution If diagnosis code U0001 is set from AS&G-ECU, surely perform CAN bus line diagnosis.
caution Replace ECU after certainly confirming that the communication circuits are normal.

TROUBLE JUDGMENT


Check Condition
  • Ignition switch is "ON" position.
Judgement Criterion
  • The microcomputer decides the system is in the bus off mode for 2 seconds.
COMMENTS ON TROUBLE SYMPTOM
  • The failure is possibly caused by malfunction of the harness and connector in CAN bus line or by malfunction in AS&G-ECU.
FAIL-SAFE AND BACKUP FUNCTION
  • In the normal operation, the auto stop is prohibited. If the malfunction is detected during the auto stop, the auto start is prohibited.

PROBABLE CAUSES



  • Failed harness and connector
  • Failed AS&G-ECU

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III CAN bus diagnosis



  • Use M.U.T.-III to perform CAN bus line diagnosis.

Q. Is the check result normal?

Go to Step 2.
Repair CAN bus line (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnostics Table ). After repairing CAN bus line, go to Step 3.

STEP 2. M.U.T.-III diagnosis code



  • Reconfirmation of diagnosis code.
Confirm again the diagnosis code is set from the AS&G-ECU.

  1. Erase the set diagnosis code.
  2. Ignition switch: "LOCK" (OFF) → ON
  3. Confirm whether the diagnosis code is set.

Q. Is the diagnosis code set?

After replacing the AS&G-ECU, go to Step 3.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 3. M.U.T.-III diagnosis code



  • Reconfirmation of diagnosis code.
Confirm again the diagnosis code is set from the AS&G-ECU.

  1. Erase the set diagnosis code.
  2. Ignition switch: "LOCK" (OFF) → ON
  3. Confirm whether the diagnosis code is set.

Q. Is the diagnosis code set?

Go to Step 1.
Check end.