Code No.U0401: Engine CAN data abnormal


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be stored. Prior to this diagnosis, diagnose the CAN bus lines.
  • Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION


4WD-ECU communicates with the engine-ECU via the CAN bus lines.

DIAGNOSIS CODE SET CONDITION


This diagnosis code will be stored when the 4WD-ECU cannot receive any signals from the engine ECU.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.
Use M.U.T.-III to perform the CAN bus diagnosis.

Q. Is the check result normal?
Go to Step 2
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). Then go to Step 5.

STEP 2. M.U.T.-III diagnosis code.
Check the engine diagnosis code (Refer to GROUP 13A - Troubleshooting <4B1>, GROUP 13B -Troubleshooting <6B3>).

Q. Is the diagnosis code stored?
Perform the relevant troubleshooting.
Go to Step 3

STEP 3. M.U.T.-III data list.
Check the following data list (Refer to ).

  • Item No.12: Engine speed

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Go to Step 4

STEP 4. Check whether the diagnosis code is stored again.

Q. Is diagnosis code No.U0401 stored?
Replace the 4WD-ECU (Refer to ). Then go to Step 5.
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 5. Check whether the diagnosis code is stored again.

Q. Is diagnosis code No.U0401 stored?
Return to Step 1.
This diagnosis is complete.