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Inspection Procedure 10: Abnormality in brake operation.
 
 
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.
 
 
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 DTC is not detected.
 
 
 
PROBABLE CAUSES
  • Brake pedal assembly malfunction
  • Brake booster assembly malfunction
  • Master cylinder assembly malfunction
  • Brake fluid line malfunction
  • ASC-ECU malfunction
 
 
 
 
DIAGNOSIS
STEP 1. 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 ).
Is the check result normal?
Go to Step 2.
Connect the brake tubes correctly, repair the external brake lines, or replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
 
STEP 2. Brake operation check
Perform the following checks.
  • Brake pedal check (Refer to GROUP 35A - On-vehicle Service, Brake Pedal Check and Adjustment ).
  • 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 ).
Is the check result normal?
Go to Step 3.
Check the brake-related parts, and repair if necessary.
 
STEP 3. Retest the system.
Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunction ).
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).