Inspection Procedure 9: 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.
  • When the hydraulic unit (integrated with ASC-ECU) is replaced, always carry out the calibration of the G and yaw rate sensor and the steering wheel sensor (Refer to and ).

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



DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis.
Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ). Then go to Step 6.

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, and repair or replace the external brake lines of the hydraulic unit (integrated with ASC-ECU). Then go to Step 6.

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 Operation 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 6.
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?
Go to Step 5.
Replace the hydraulic unit assembly (integrated with ASC-ECU) (Refer to ). Then go to Step 6.

STEP 5. Retest the system.

Q. Does the brake operate normally?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction).
Replace the hydraulic unit assembly (integrated with ASC-ECU) (Refer to ). Then go to Step 6.

STEP 6. Retest the system.

Q. Does the brake operate normally?
This diagnosis is complete.
Return to Step 1.