Inspection Procedure 5: Brake Warning Lamp does not Illuminate when the Ignition Switch is Turned to ON Position (Engine Stopped).




OPERATION


ASC-ECU sends the illumination request signal of the break warning 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 - Troubleshooting ).

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, 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, and then go to Step 5.
Replace the ASC-ECU, and then go to Step 5.

STEP 5. Retest the system.


Q. Does the brake warning lamp turn ON and OFF normally?

This diagnosis is complete.
Return to Step 1.