Inspection Procedure 11: ASC does not Operate or Faulty ASC Operate.


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 ).

COMMENTS ON TROUBLE SYMPTOM
In case of this trouble symptom, the stability control/TCL system operation may be disabled. Diagnosis code may be set by the stability control/TCL system using M.U.T.-III.

PROBABLE CAUSES

  • Low battery output
  • Wiring harness or connector failure of CAN bus line
  • ASC-ECU malfunction
  • Engine coding data problem

DIAGNOSIS PROCEDURE

STEP 1. Diagnosis code check
Use M.U.T.-III to check the diagnosis code for the ASC system. (Refer to .)

Q. Is the check result normal?
Go to Step 2.
Carry out the diagnosis for the diagnosis code. (Refer to .)

STEP 2. Engine ECU coding data check
Using M.U.T.-III, check if any abnormality is present to the coding data below which are stored in the engine-ECU. (Refer to GROUP 00 - Coding List .)
A.S.C.
    OK: Available

Q. Is the check result normal?
Go to Step 3.
Replace the engine ECU. <Refer to GROUP 13A - Engine-ECU (4A9) or GROUP 13B - Engine-ECU (4B1) or GROUP 13D - Engine-ECU (BWC) or GROUP 13C - Engine-ECU (4B1-T/C).> Then go to Step 4 .

STEP 3. Hydraulic unit (integrated with ASC-ECU) check
Check that the brake tube is correctly mounted to the hydraulic unit (integrated with ASC-ECU). (Refer to .)

Q. Is the check result normal?
Replace the hydraulic unit (integrated with ASC-ECU).(Refer to .) Then go to Step 4.
Connect the brake tubes correctly, and repair or replace the external brake lines of the hydraulic unit (integrated with ASC-ECU).

STEP 4. Operation check

Q. Does stability control/TCL operate normally?
This diagnosis is complete.
Check the brake system related components other than the stability control/TCL system.