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
Malfunction of immobilizer-ECU

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 54D - 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)Erase the diagnosis code.

(2)Turn the ignition switch to the "LOCK" (OFF) position once, and then turn it to the "ON" position again.

(3)Check if the diagnosis code is set.

Q. Is the check result normal?

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

Replace the immobilizer-ECU and register the ID codes (Refer to

). After registering the ID codes, 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 the "LOCK" (OFF) position once, and then turn it to the "ON" position again.

(3)Check if the diagnosis code is set.

Q. Is the check result normal?

The procedure is complete.

Return to Step 1.