Code No. U0001: Malfunction of bus-off

caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, always diagnose the CAN bus lines.
  • Before replacing the ECU, ensure that the communication circuit is normal.

OPERATION



DIAGNOSIS CODE SET CONDITIONS




  • IG1 voltage: 10 V or more
  • When CAN C-bus off interruption is detected

PROBABLE CAUSES


Current trouble
  • Wiring harness or connector failure of CAN bus line
  • 4WD-ECU malfunction
Past trouble
  • Intermittent wiring harness or connector failure
    note For diagnosis procedures, refer to "How to treat past trouble". (Refer to GROUP 00, How to Treat Past Trouble .)

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
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 line. (Refer to GROUP 54C - Troubleshooting .) Then go to Step 2.

STEP 2. Check the following connector:
Check the connectors below for improper engagement, terminal damage or terminal drawn in the connector case.

  • C-130 4WD-ECU connector
  • C-313, C-317 ETACS-ECU connector

Q. Are the connectors and terminals in good condition?
Go to Step 3.
Repair the connector(s) or terminal(s). Then go to Step 5.

STEP 3. Wiring harness check
Check the wiring harness between the C-130 4WD-ECU connector and the C-313 ETACS-ECU connector for damage or other problem.

Q. Is the wiring harness in good condition?
Go to Step 4.
Repair damage or other problem in the wiring harness. Then go to Step 5.

STEP 4. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code No. U0001 set?
Replace 4WD-ECU. (Refer to .) Then go to Step 5.
The trouble can be an intermittent malfunction such as loose connector fit, wiring harness open circuit. (Refer to GROUP - How to Cope with Intermittent Malfunction .)

STEP 5. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. U0001 set?
Diagnose again from Step 1.
This diagnosis is complete.