Inspection Procedure 10: Abnormality in brake operation


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.

COMMENTS ON TROUBLE SYMPTOM
Although the cause of the trouble cannot be clearly resolved since it depends on the running status and road surface condition, the malfunction of the hydraulic circuit may occur if any diagnosis code is not detected.

PROBABLE CAUSES

  • Hydraulic unit (Integrated with ASC-ECU) malfunction
  • Malfunction of hydraulic circuit
  • Malfunction of brake assembly
  • Malfunction of brake booster
  • Malfunction of master cylinder assembly

DIAGNOSIS PROCEDURE

STEP 1. Diagnosis code check
Use M.U.T.-III to check the diagnosis code for the ASC system. (Refer to .)

Q. Is the check result normal?
Go to Step 2
Troubleshoot for the relevant diagnosis code (Refer to ).

STEP 2. Hydraulic unit (Integrated with ASC-ECU) check
Check that the brake tube is installed to the hydraulic unit (integrated with ASC-ECU) correctly (Refer to ).

Q. Is the check result normal?
Go to Step 3
Connect the brake tubes correctly, repair the external brake lines, or replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).

STEP 3. Brake operation check
Perform the following checks.

  • Brake pedal check (Refer to GROUP 35A - On-vehicle Service/Brake Pedal Check ).
  • Brake booster check (Refer to GROUP 35A - On-vehicle Service/Brake Booster Operating Check ).
  • Check valve check (Refer to GROUP 35A - On-vehicle Service/Check Valve Operation Check ).

Q. Can any fault be found with the brake operation?
Check the brake-related parts, and repair if necessary. Then, go to Step 4.
Go to Step 4

STEP 4. Hydraulic unit check
Perform the following actuator tests (Refer to ).

  • Item No.01: FL wheel ABS drive
  • Item No.02: FR wheel ABS drive
  • Item No.03: RL wheel ABS drive
  • Item No.04: RR wheel ABS drive
  • Item No.05: FL wheel TCL drive
  • Item No.06: FR wheel TCL drive
  • Item No.07: RL wheel TCL drive
  • Item No.08: RR wheel TCL drive

Q. Is the check result normal?
This diagnosis is complete.
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).