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Inspection Procedure 3: The brake warning light does not go out (ABS warning light is OFF) although the parking brake is released.
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC 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
  • The combination meter illuminates the brake warning light when the parking brake is applied.
  • 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 light.
 
 
 
PROBABLE CAUSES
  • The brake pad thickness is at the limit value or less.
  • The brake fluid amount is at the "LOWER" level or lower.
  • Combination meter malfunction (related to parking brake signal)
  • ETACS-ECU malfunction (related to brake fluid level switch signal)
  • ASC-ECU malfunction
  • Electric parking brake ECU malfunction
 
 
 
 
DIAGNOSIS
STEP 1. Brake fluid level check
Check that the brake fluid is filled up to the "MIN" level or higher.
Is the check result normal?
Go to Step 4.
Go to Step 2.
 
STEP 2. Brake pad check
Refer to GROUP 35A - On-vehicle Service/Brake Pad Check .
Is the check result normal?
Fill the brake fluid up to the "MAX" level. Then go to Step 3.
Replace the brake pad (Refer to GROUP 35A - On-vehicle Service/Brake Pad Replacement ).
 
STEP 3. Brake fluid leak check
  • Master cylinder assembly and brake tubes (Refer to GROUP 35A - Master Cylinder Assembly and Brake Booster ).
  • Hydraulic unit assembly and brake tubes (Refer to ).
  • Front brake caliper, brake tubes and brake hoses (Refer to GROUP 35A - Front disc brake assembly ).
  • Rear brake caliper, brake tubes and brake hoses (Refer to GROUP 35A - Rear disc brake assembly ).
Is the check result normal?
Fill the brake fluid up to the "MAX" level. Then go to Step 4.
Repair or replace it.
 
STEP 4. Using scan tool (M.U.T.-IIISE) data list
Check the ETACS-ECU data list (Refer to GROUP 54A - ETACS, Troubleshooting, Data list reference table ).
  • Item No.102: Brake fluid switch
Is the check result normal?
Go to Step 8.
Go to Step 5.
 
STEP 5. Brake fluid level switch check
Refer to GROUP 35A - On-vehicle Service/Brake Fluid Level Switch Check .
Is the check result normal?
Go to Step 6.
Replace the reservoir assembly (Refer to GROUP 35A - Master Cylinder disassembly and reassembly).
 
STEP 6. 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 (ground terminal) and the body ground.
OK: The resistance should be 2 ohms or less
Is the check result normal?
Go to Step 7.
The open circuit may be present in the ground circuit. Repair the wiring harness between the brake fluid level switch connector and the body ground.
 
STEP 7. Check of open circuit in BFSW line between ETACS-ECU connector and brake fluid level switch connector
Is the check result normal?
Replace the ETACS-ECU (Refer to GROUP 54A - ETACS-ECU ).
Repair the connector(s) or wiring harness.
 
STEP 8. Using scan tool (M.U.T.-IIISE) data list
Check the electric parking brake ECU data list (Refer to GROUP 36 - Troubleshooting, Data list reference table ).
  • Item No.49: EPB active indicator
Is the check result normal?
Go to Step 9.
Replace the electric parking brake ECU (Refer to GROUP 36 - Electric Parking Brake ECU )
 
STEP 9. Using scan tool (M.U.T.-IIISE) special function
Perform the combination meter special function (Refer to GROUP 54A - Combination Meter/Special function table ).
  • Item No.9: Indicator (AUTO)
Is the check result normal?
Go to Step 10.
Replace the combination meter assembly(Refer to GROUP 54A - Combination Meter ).
 
STEP 10. Retest the system.
Does the brake warning light turn ON and OFF normally according to the parking brake operation?
Intermittent malfunction (Refer to GROUP 00 - How to Use Trouble shooting/How to Cope with Intermittent Malfunction).
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).