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.
TROUBLESHOOTING HINTS
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
STEP 1. Scan tool (M.U.T.-III) DTC
(1)
caution
To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(2) Check the DTC for the ASC system.
Is the DTC set?
Troubleshoot for the relevant DTC (Refer to ).
Go to Step 2.
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 ).
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 ).
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
Is the check result normal?
This diagnosis is complete.
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).