Inspection Procedure 8: 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 - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION

  • ASC-ECU sends the illumination request signal of ASC OFF lamp to the combination meter through ETACS-ECU via CAN communication.
  • By the operation of ASC OFF switch, the ASC OFF lamp 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 - CAN Bus Diagnostics Table ). Then go to Step 8.

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 Special Function for other system
Perform the following special function by the combination meter system, and check if the ABS warning lamp illuminates (Refer to GROUP 54A - Combination Meter ).

  • Item 2: LCD (AUTO)

Q. Is the check result normal?
Go to Step 4
Replace the combination meter. Then go to Step 8.

STEP 4. M.U.T.-III data list for other system
Check the ETACS-ECU system data list.

  • ASC OFF switch: During ON operation
Item No.
 Item name
 Normal condition
281
 ASC/TCL OFF switch
 ON

Q. Is the check result normal?
Go to Step 5
Refer to GROUP 54A - ETACS, Inspection Procedure 15 "The ASC OFF switch signal is not received." .

STEP 5. M.U.T.-III diagnosis code for other systems
Using M.U.T.-III, check that diagnosis code No. U0141 is not set by the combination meter system.

Q. Is the diagnosis code set?
Diagnose the combination meter (Refer to GROUP 54A - Combination Meter/Diagnosis Code ). Then go to Step 8.
Go to Step 6

STEP 6. M.U.T.-III diagnosis code for other systems
Using M.U.T.-III, check that diagnosis code No. U0121 is not set by the ETACS system.

Q. Is the diagnosis code set?
Perform troubleshooting on ETACS-ECU (Refer to GROUP 54A - ETACS/Diagnosis Code ). Then go to Step 7.
Go to Step 7

STEP 7. Retest the system.

Q. Does ASC OFF lamp turn ON and OFF normally?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ). Then go to Step 8.

STEP 8. Retest the system.

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