Code No. U1073: Bus Off


caution If diagnosis code U1073 is output from engine-ECU surely perform CAN busline diagnosis.
caution Replace ECU after certainly confirming that the communication circuits are normal.

TROUBLE JUDGMENT


Check Condition
Judgment Criterion
COMMENT ON TROUBLE SYMPTOM

PROBABLE CAUSE



DIAGNOSIS PROCEDURE

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

  • Using M.U.T.-III, perform CAN busline diagnosis.

Q. Is the check result normal?
Go to Step 2 .
Correct CAN busline (Refer to 54D - Troubleshooting - Can Bus Diagnostics Table ), and then go to Step 3 .

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

  • Reconfirm whether the diagnosis codes are output from engine-ECU.

  1. Erase the diagnosis codes being output.
  2. Ignition switch: "LOCK" (OFF) to ON
  3. Confirm whether the diagnosis codes are output.

Q. Are the diagnosis codes output?
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, the vehicle equipped with the closed type DPF carries out the forcible DPF regeneration. (Refer to GROUP 17 - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ), and then 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

  • Reconfirm whether the diagnosis codes are output from engine-ECU.

  1. Erase the diagnosis codes being output.
  2. Ignition switch: "LOCK" (OFF) to ON
  3. Confirm whether the diagnosis codes are output.

Q. Are the diagnosis codes output?
Go to Step 1 .
The check is end.