Inspection Procedure 18: ESS inoperative or improper operative


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.

COMMENTS ON TROUBLE SYMPTOM
In case of this trouble symptom, ESS operation may be disabled. Diagnosis code may be set by the ASC system using M.U.T.-III.
note Before carrying out the troubleshooting, ask the user and confirm the driving conditions when the failure has occurred.

PROBABLE CAUSES

  • Low battery voltage
  • Wiring harness or connector failure of CAN bus line
  • The ASC-ECU is defective.
  • Different ETACS-ECU, abnormal variant coding information
  • Different ASC-ECU.
  • Malfunction of ETACS-ECU.

DIAGNOSIS PROCEDURE

STEP 1. Hydraulic unit (integrated with ASC-ECU) check
Check the hydraulic unit (integrated with ASC-ECU) part No.

Q. Is the check result normal?
Go to Step 2
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ). Then go to Step 2.

STEP 2. ETACS-ECU check
Check the ETACS-ECU part No.

Q. Is the check result normal?
Go to Step 3
Replace ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ). Then go to Step 3.

STEP 3. Diagnosis code check
Use M.U.T.-III to check the diagnosis code for the ASC system and ETACS-ECU (Refer to and GROUP 54A - ETACS/Diagnosis code chart ).

Q. Is the check result normal?
Go to Step 4
Carry out the diagnosis for the diagnosis code. (Refer to or GROUP 54A - ETACS/Diagnosis code chart ). Then go to Step 4.

STEP 4. M.U.T.-III actuator test
Perform the following actuator test, and check if the ESS operation (Refer to ).

  • Item No.10: ESS test mode

Q. Is the check result normal?
This diagnosis is complete.
Go to Step 5

STEP 5. Check ETACS coding data
Refer to GROUP 00 - Precautions before Service/Coding List .

Q. Is the check result normal?
Go to Step 6
Replace ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ). Then go to Step 9.

STEP 6. Check the ASC-ECU power supply circuit.
Refer to .

Q. Is the check result normal?
Go to Step 7
Carry out the diagnosis of ASC-ECU power supply circuit system (Refer to ). Then go to Step 9.

STEP 7. M.U.T.-III actuator test
Perform the following actuator test, and check if the ESS operation (Refer to ).

  • Item No.10: ESS test mode

Q. Is the check result normal?
This diagnosis is complete.
Replace ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ). Then go to Step 8.

STEP 8. M.U.T.-III actuator test
Perform the following actuator test, and check if the ESS operation (Refer to ).

  • Item No.10: ESS test mode

Q. Is the check result normal?
This diagnosis is complete.
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ). Then go to Step 9.

STEP 9. M.U.T.-III actuator test
Perform the following actuator test, and check if the ESS operation (Refer to ).

  • Item No.10: ESS test mode

Q. Is the check result normal?
This diagnosis is complete.
Return to Step 1.