Code No.U1073 Bus Off


caution
  • If diagnosis code U1073 is set in the centre display or multi display station, always diagnose the CAN bus lines.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.

TROUBLE JUDGMENT


If the centre display unit or multi display station ceases communicating once (i.e. bus off) and then returns to it, the centre display unit or multi display station will not communicate for three minutes immediately after that point. This three-minute period is called "Penalty mode." Immediately after the centre display unit or multi display station returns to communication, the diagnosis code is set.

COMMENTS ON TROUBLE SYMPTOM


The CAN bus line wiring harness, connector(s), or the centre display unit or multi display station unit may be defective.

POSSIBLE CAUSES



DIAGNOSIS PROCEDURE


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


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

Q. Is the check result satisfactory?

Go to Step 2.

Repair the CAN bus lines (Refer to GROUP 54D - Diagnosis ). Repair the CAN bus line and go to Step 3.

STEP 2. Check whether the diagnosis code is reset.


Recheck if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Turn the ignition switch to "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the check result satisfactory?

If the trouble is solved, it is determined that there is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

Replace centre display unit or multi display station and then go to step 3.

STEP 3. Check whether the diagnosis code is reset.


Recheck if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Turn the ignition switch to "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the check result satisfactory?

The procedure is complete.

Go to Step 1.