Inspection Procedure 13: 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.
  • When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the G and yaw rate sensor and the steering wheel sensor (Refer to and ).

COMMENTS ON TROUBLE SYMPTOM


When the ASC system has stored the diagnosis code, the ESS may be disabled.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Check the part number of the hydraulic unit (integrated with ASC-ECU).
Check the part number of the hydraulic unit (integrated with ASC-ECU).

Q. Is the check result normal?
Go to Step 2.
Replace the hydraulic unit (integrated with ASC-ECU). (Refer to ). Then go to Step 9.

STEP 2. Check part number of ETACS-ECU.
Check the part number of ETACS-ECU.

Q. Is the check result normal?
Go to Step 3.
Replace ETACS-ECU. (Refer to GROUP 54A - ETACS-ECU). Then go to Step 9 .

STEP 3. Check the diagnosis code.
Use the M.U.T.-III to check whether the ASC system and the ETACS-ECU set a diagnosis code.

Q. Is the check result normal?
Go to Step 4.
Diagnose the system according to the relevant diagnosis code procedure. (Refer to <ASC> or Refer to GROUP 54A - ETACS, Diagnosis Code Chart). Then go to Step 9.

STEP 4. M.U.T.-III actuator test.
Perform the actuator test below to function-check the emergency braking signal system (Refer to ).

  • Item No. 10: ESS test mode

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction).
Go to Step 5.

STEP 5. ETACS-ECU coding data check.
Using M.U.T.-III, check if any abnormality is present in the coding data below which is stored in the ETACS-ECU. (Refer to GROUP 00 - Coding Reference Table ).
ESS
    OK: Available

Q. Is the check result normal?
Go to Step 6.
Replace 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.
Diagnose the power supply circuit to the ASC-ECU (Refer to ). Then go to Step 9.

STEP 7. M.U.T.-III actuator test.
Perform the actuator test below to function-check the emergency braking signal system (Refer to ).

  • Item No. 10: ESS test mode

Q. Is the check result normal?
The trouble can be an 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 8 .

STEP 8. Retest the system.
Perform the actuator test below to function-check the emergency braking signal system (Refer to ).

  • Item No. 10: ESS test mode

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction).
Replace the hydraulic unit (integrated with ASC-ECU). (Refer to .) Then go to Step 9.

STEP 9. Retest the system.
Perform the actuator test below to function-check the emergency braking signal system (Refer to ).

  • Item No. 10: ESS test mode

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