Inspection Procedure 2: Brake warning lamp stays ON with the parking brake lever released.


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

  • When the parking brake switch is turned ON, the combination meter (BRK terminal) is earthed, and then the brake warning lamp illuminates.
  • When reduction of the brake fluid amount is detected, the brake fluid level switch is turned from ON to OFF. ETACS-ECU monitors the brake fluid level switch, and instructs the combination meter via the CAN bus line to illuminate the brake warning lamp.

COMMENTS ON TROUBLE SYMPTOM
This may be caused by earth fault in the parking brake switch circuit.

PROBABLE CAUSES

  • The brake pad thickness is at the limit value or less.
  • The brake fluid amount is at the "LOWER" level or lower.
  • Poor adjustment of the parking brake lever
  • Damaged wiring harness and connectors
  • Parking brake switch malfunction
  • Brake fluid level switch malfunction
  • Combination meter malfunction
  • ETACS-ECU malfunction

DIAGNOSTIC 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 ).

STEP 2. M.U.T.-III diagnosis code for other systems.
Use M.U.T.-III to check that the diagnosis code is set in the combination meter and ETACS-ECU.

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

STEP 3. Brake fluid level check
Check that the brake fluid is filled up to the "MIN" level or higher.

Q. Is the check result normal?
Go to Step 5.
Go to Step 4.

STEP 4. Brake pad check
Refer to GROUP 35A - On-vehicle Service/Brake Pad Check .

Q. Is the check result normal?
Fill the brake fluid up to the "MAX" level. Then go to Step 5.
Replace the brake pad (Refer to GROUP 35A - On-vehicle Service/Brake Pad Replacement ). Then go to Step 14.

STEP 5. M.U.T.-III data list for other system
Check the ETACS-ECU system data list.
Item No.
 Item name
 Normal condition
279
 Brake fluid switch
 ON

Q. Is the check result normal?
Go to Step 10.
Go to Step 6.

STEP 6. Brake fluid level switch check
Refer to GROUP 35A - On-vehicle Service/Brake Fluid Level Switch Check .

Q. Is the check result normal?
Go to Step 7.
Replace the reservoir tank assembly (Refer to GROUP 35A - Master Cylinder Assembly and Brake Booster <LHD> or <RHD>). Then go to Step 14.

STEP 7. Resistance measurement at brake fluid level switch connector.
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between the brake fluid level switch connector (earth terminal) and the body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?
Go to Step 9.
Go to Step 8.

STEP 8. Check of open circuit in earth line between brake fluid level switch connector and the body earth

Q. Is the check result normal?
Go to Step 9.
Repair the connector(s) or wiring harness.

STEP 9. Check of short to power supply, short to earth, and open circuit in HL1+ line between ETACS-ECU connector and brake fluid level switch connector

Q. Is the check result normal?
Replace the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ). Then go to Step 14.
Repair the connector(s) or wiring harness.

STEP 10. Parking brake lever stroke check
Refer to GROUP 36 - On-vehicle Service/Parking Brake Lever Stroke Check and Adjustment .

Q. Is the check result normal?
Go to Step 11.
Adjust the parking brake lever stroke (Refer to GROUP 36 - On-vehicle Service/Parking Brake Lever Stroke Check and Adjustment ). Then go to Step 14.

STEP 11. Parking brake switch check
Refer to GROUP 36 - On-vehicle Service/Parking Brake Switch Check .

Q. Is the check result normal?
Go to Step 12.
Replace the parking brake switch (Refer to GROUP 36 - Parking Brake Lever ). Then go to Step 14.

STEP 12. Check of short to power supply, short to earth, and open circuit in BRK line between combination meter connector and parking brake switch connector

Q. Is the check result normal?
Go to Step 13.
Repair the connector(s) or wiring harness.

STEP 13. Retest the system.

Q. Does the brake warning lamp turn ON and OFF normally according to the parking brake lever operation?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
Replace the combination meter assembly (Refer to GROUP 54A - Combination Meter ). Then go to Step 14.

STEP 14. Retest the system.

Q. Does the brake warning lamp turn ON and OFF normally according to the parking brake lever operation?
This diagnosis is complete.
Return to Step 1.