Inspection Procedure 14: 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, Trouble code diagnosis ).
  • 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.

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. 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 2.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnosis table ). On completion, go to Step 2.

STEP 2. 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, Check Chart for Diagnosis codes .)

Q. Is the check result normal?
Go to Step 3.
Carry out the diagnosis for the diagnosis code. (Refer to or GROUP 54A - ETACS, Check Chart for Diagnosis codes .) Then go to Step 9.

STEP 3. 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?
Go to Step 8.
Go to Step 4.

STEP 4. 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 5.
Replace the hydraulic unit (integrated with ASC-ECU). (Refer to .) Then go to Step 9.

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 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. Operation check

Q. Does the ESS work normally?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction .)
Replace ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ). Then go to Step 9.

STEP 8. Operation check

Q. Does the ESS work normally?
This diagnosis is complete.
Replace the hydraulic unit (integrated with ASC-ECU). (Refer to .) Then go to Step 9.

STEP 9. Operation check

Q. Does the ESS work normally?
This diagnosis is complete.
Return to Step 1.