Code No. U0100 Engine time-out error
Code No. U0121 ABS time-out error
Code No. U0141 ETACS time-out error


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, CAN Bus Diagnostics Table).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION

    The signals from the engine-ECU, ABS-ECU <vehicles with ABS>, ASC-ECU <vehicles with ASC>, and ETACS-ECU are sent to the EPS-ECU.

FUNCTION

    The signals from the engine-ECU, ABS-ECU <vehicles with ABS>, ASC-ECU <vehicles with ASC>, and ETACS-ECU are sent to the EPS-ECU for motor control.

TROUBLE JUDGEMENT
Check Conditions
  • The power supply circuit system diagnosis code (No. C1540, C1541) is not set.
  • The diagnosis code related to engine circuit system, ABS circuit system <vehicles with ABS>, ASC circuit system <vehicles with ASC>, and ETACS circuit system is set.
Judgement Criterion
    The signals from the engine-ECU, ABS-ECU <vehicles with ABS>, ASC-ECU <vehicles with ASC>, and ETACS-ECU are not sent, and the microcomputer determines that there is a problem in the system.
Fail Safe, Back Up Function
  • The EPS-ECU illuminates the electric power steering warning display, and sets the diagnosis code Nos. U0100, U0121, and U0141. However, the assist operation is limited only with the diagnosis code No. U0121.

PROBABLE CAUSES

  • Malfunction of CAN bus line
  • Malfunction of the EPS-ECU
  • Malfunction of the engine-ECU
  • Malfunction of the ETACS-ECU
  • Malfunction of the ABS-ECU <vehicles with ABS>
  • Malfunction of the ASC-ECU <vehicles with ASC>

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis codes U0100, U0121 or U0141 set?
Go to Step 3.
This diagnosis is complete.

STEP 3. M.U.T.-III diagnosis code
Use M.U.T.-III to check if the same diagnosis code (time-out) is set in the other ECU (CAN-C).

Q. Is any diagnosis code set?
YES (Code No. U0100 is set) : Replace the engine ECU, and then go to Step 4.
YES (Code No. U0121 is set) : Replace the ABS-ECU <vehicles with ABS>, ASC-ECU <vehicles with ASC>, and then go to Step 4.
YES (Code No. U0141 is set) : Replace the ETACS-ECU, and then go to Step 4.
NO (No diagnosis code is set.) : Go to Step 4.

STEP 4. Check whether the diagnosis code is reset
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis codes U0100, U0121 or U0141 set?
Replace the EPS-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 reset
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis codes U0100, U0121 or U0141 set?
Return to Step 1.
This diagnosis is complete.