Code No.U1073: Bus Off


caution If diagnosis code No.U1073 is set in the immobilizer-ECU, diagnose the CAN bus lines.
caution Whenever the ECU is replaced, ensure that the input and output signal circuits are normal.

TROUBLE JUDGMENT


Code No.U1073 will be set when the immobilizer-ECU ceases CAN communication (bus off), and the code will be stored when the ECU resumes the communication.

COMMENTS ON TROUBLE SYMPTOM


The wiring harness wire or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector, or the immobilizer communication lines may be defective.

PROBABLE CAUSES


Damaged harness wires and connectors

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 normal?

Go to Step 2.

Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ). Repair the CAN bus line and go to Step 3.

STEP 2. Check whether the diagnosis code is reset.


Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "LOCK" (OFF) position once, and then turn it to the ON position again.
(2)Check that diagnosis code No.U1073 is not set as a current trouble.

Q. Is diagnosis code No.U1073 set as a current trouble?

Replace the immobilizer-ECU and register the ID codes. (Refer to .) After registering the ID codes, go to Step 3.

If a 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 ).

STEP 3. Check whether the diagnosis code is reset.


Recheck if the diagnosis code is set.
(1)Turn the ignition switch to the "LOCK" (OFF) position once, and then turn it to the ON position again.
(2)Check that diagnosis code No.U1073 is not set as a current trouble.

Q. Is diagnosis code No.U1073 set as a current trouble?

Return to Step 1.

Erase the diagnosis code that is set as a past trouble, and the diagnosis is complete.