Inspection Procedure 8: ASC OFF Display or ASC OFF 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 ASC OFF display to the combination meter through ETACS-ECU via CAN communication.
  • By the operation of ASC OFF switch, the ASC OFF display illuminates when the ASC function is stopped.
  • When the ASC OFF switch is pressed for 3 seconds or more, the ASC system turns OFF.
  • When the ASC OFF switch is pressed for 15 seconds or more, the ASC is kept in ON state and the system cannot be turned OFF until the ignition switch is turned to the ON position next time.

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 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 - Troubleshooting .) Then go to Step 9.

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. ASC OFF switch check
Refer to .

Q. Is the check result normal?
Go to Step 4.
Replace ASC OFF switch.(Refer to .) Then go to Step 9.

STEP 4. Connector check: C-313 ETACS-ECU connector, C-36 intermediate connector, C-102 ASC OFF switch connector

Q. Is the check result normal?
Go to Step 5.
Repair the damaged connector.

STEP 5. Wiring harness check between C-313 ETACS-ECU connector terminal No. 15 and C-102 ASC OFF switch connector terminal No. 1

  • Check the power supply circuit for short circuit.

Q. Is the check result normal?
Go to Step 6.
Repair the wiring harness between C-313 ETACS-ECU connector terminal No. 15 and C-102 ASC OFF switch connector terminal No. 1.

STEP 6. M.U.T.-III diagnosis code for other systems
Using M.U.T.-III, check that diagnosis code No. U0141 is set by the combination meter system.

Q. Is the diagnosis code set?
Diagnose the combination meter. (Refer to GROUP 54A - Combination Meter, Troubleshooting .) Then go to Step 9.
Go to Step 7.

STEP 7. M.U.T.-III diagnosis code for other systems
Using M.U.T.-III, check that diagnosis code No. U0121 is set by the ETACS system.

Q. Is the diagnosis code set?
Perform troubleshooting on ETACS-ECU. (Refer to GROUP 54A - ETACS, Troubleshooting .) Then go to Step 8.
Go to Step 8.

STEP 8. Retest the system.

Q. Does ASC OFF display turn ON and OFF normally?
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.

Q. Does ASC OFF display turn ON and OFF normally?
This diagnosis is complete.
Return to Step 1.