Inspection Procedure 4: Brake warning lamp does not illuminate when the ignition switch is turned to ON position (Engine stopped).


OPERATION
ABS-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 ABS-ECU.

PROBABLE CAUSES

  • Damaged wiring harness and connectors
  • Malfunction of ETACS-ECU
  • Combination meter malfunction
  • ABS-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 ), and then go to Step 6.

STEP 2. M.U.T.-III diagnosis code
Use M.U.T.-III to check the diagnosis code for the ABS system.

Q. Is the diagnosis code set?
Carry out the diagnosis for the diagnosis code (Refer to ).
Go to Step 3.

STEP 3. Actuator test of combination meter
Refer to GROUP 54A - Combination meter .

Q. Is the check result normal?
Go to Step 4.
Troubleshoot the combination meter. Then go to Step 6.

STEP 4. 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 6.
Go to Step 5.

STEP 5. 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 6.
Replace the ABS-ECU (Refer to ), and then go to Step 6.

STEP 6. Retest the system.

Q. Does the brake warning lamp turn ON and OFF normally?
The procedure is complete.
Return to Step 1.