Inspection Procedure 9: ASC Indicator Lamp Stays ON after the Engine is Started.



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

OPERATION


ASC-ECU sends the illumination request signal of the ASC indicator lamp to the combination meter through ETACS-ECU via the CAN communication.

COMMENTS ON TROUBLE SYMPTOM


This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ASC-ECU.

PROBABLE CAUSES



  • Damaged wiring harness and connectors
  • Malfunction of ETACS-ECU
  • Combination meter malfunction
  • ASC-ECU malfunction

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III CAN bus diagnosis


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 ).

STEP 2. M.U.T.-III diagnosis code


Use M.U.T.-III to check the diagnosis code for the ASC system.

Q. Is the diagnosis code set?

Carry out the diagnosis for the diagnosis code (Refer to ).
Go to Step 3.

STEP 3. M.U.T.-III other system diagnosis code


Using M.U.T.-III, check that the diagnosis code No. U0141 is not set by the combination meter system.

Q. Is the diagnosis code set?

Troubleshoot the combination meter (Refer to GROUP 54A - Combination meter, Diagnosis troubleshooting flow ), and then go to Step 5.
Go to Step 4.

STEP 4. M.U.T.-III other system diagnosis code


Using M.U.T.-III, check that the diagnosis code No. U0121 is not set by the ETACS system.

Q. Is the diagnosis code set?

Troubleshoot the ETACS (Refer to GROUP 54A - ETACS, Diagnosis troubleshooting flow ), and then go to Step 5.
Replace the ASC-ECU (Refer to ), and then go to Step 5.

STEP 5. Retest the system.


Q. Does the ASC indicator lamp turn ON and OFF normally?

This diagnosis is complete.
Return to Step 1.