Inspection Procedure 6: Abnormality In Brake Operation

Inspection Procedure 6: 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.
^ 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
^ Malfunction of hydraulic unit (integrated with ABS-ECU)
^ Malfunction of hydraulic circuit
^ Malfunction of brake assembly
^ Malfunction of brake booster
^ Malfunction of master cylinder assembly

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III DTC
Use scan tool to check the DTC for the ABS system.

Q: Is the check result normal?
YES: Go to Step 2.
NO: Carry out the diagnosis for the DTC.

STEP 2. Hydraulic unit (integrated with ABS-ECU) check
Check that the brake tube is correctly mounted to the hydraulic unit (integrated with ABS-ECU).

Q: Is the check result normal?
YES: Go to Step 3.
NO: Connect the brake tubes correctly, and repair or replace the external brake lines of the hydraulic unit (integrated with ABS-ECU).

STEP 3. Brake operation check
Perform the following checks.
^ Brake pedal check.
^ Brake booster check.
^ Check valve check.

Q: Can any fault be found with the brake operation?
YES: Check the brake-related parts, and repair if necessary. Then, go to Step 4.
NO: Go to Step 4.

STEP 4. Hydraulic unit check
Perform the following actuator tests.
^ Item No.01: FL wheel ABS
^ Item No.02: FR wheel ABS
^ Item No.03: RL wheel ABS
^ Item No.04: RR wheel ABS

Q: Is the check result normal?
YES: The procedure is complete.
NO: Replace the ABS-ECU.