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 CAUSES



DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
warning Since the radiator fan rotates during CAN bus line diagnostics, make sure that no one is servicing the engine compartment before diagnosing the CAN bus line. Since the CAN communication stops when diagnosing the CAN bus line, the ETACS-ECU detects the time-out of the engine-ECU, and activates the radiator fan to prevent overheating as fail-safe.

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

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

STEP 2. Reconfirmation of diagnosis codes

  • 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. Is the diagnosis code output?
After replacing the engine-ECU, 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. Reconfirmation of diagnosis codes

  • 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. Is the diagnosis code output?
Go to Step 1 .
The check is completed.