Inspection Procedure 10: 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 ABS system using M.U.T.-III.

PROBABLE CAUSES

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

DIAGNOSIS PROCEDURE

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

Q. Is the check result normal?
Go to Step 2.
Replace the hydraulic unit (integrated with ABS-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 ABS system and ETACS-ECU (Refer to 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 GROUP 54A - ETACS, Diagnosis Codes Chart ).

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 - Coding List .
ESS type
    OK: Present

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 ABS-ECU power supply circuit.

Q. Is the check result normal?
Go to Step 7.
Carry out the diagnosis of ABS-ECU power supply circuit system. 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 ABS-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.