Inspection Procedure 3: Brake warning lamp does not illuminate when the electric motor switch is turned to ON position.

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 the brake warning lamp to the combination meter through the CAN communication.
ASC-ECU illuminates brake warning lamp for approximately 3 seconds for bulb check with the electric motor switch turned to the "ON" position.

COMMENTS ON TROUBLE SYMPTOM

This may be caused by faults in the CAN bus line, combination meter or ASC-ECU.

PROBABLE CAUSES

Damaged wiring harness and connectors
Malfunction of the combination meter
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 6.

STEP 2. M.U.T.-III diagnosis code

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

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

Perform the following actuator test by the combination meter system, and check if the brake warning lamp illuminates (Refer to GROUP 54A - Combination Meter/Actuator Test Table

Item No.07: Indicator 1

Q. Is the check result normal?

	Go to Step 5.

	Diagnose the combination meter (Refer to GROUP 54A - Combination Meter/Trouble Symptom Chart ). Then go to Step 4.

STEP 4. M.U.T.-III diagnosis code for other systems

Using M.U.T.-III, check that the diagnosis code 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 6.

	Go to Step 5.

STEP 5. Retest the system.

Q. Does the brake warning 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 ), and then go to Step 6.

STEP 6. Retest the system.

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

	This diagnosis is complete.

	Return to Step 1.

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