Inspection Procedure 11: ESS inoperative or improper operative.


caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be stored. Prior to this diagnosis, always 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 steering wheel sensor and the G and yaw rate sensor (Refer to and ).

COMMENTS ON TROUBLE SYMPTOM


Because the ASC system has stored the diagnosis code, the emergency brake signal system (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 (Refer to ) and the ETACS-ECU store a diagnosis code (Refer to GROUP 54A - ETACS, Diagnosis Code Chart ).

Q. Is the check result normal?
Go to Step 4.
Diagnose the system according to the relevant diagnosis code procedure, and then go to Step 8.

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 (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.
Diagnose the power supply circuit to the ASC-ECU (Refer to ). Then go to Step 9.

STEP 7. 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 ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ). Then go to Step 9.

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.