Inspection Procedure 10

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 CAN Bus Diagnostics Chart).

- 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 steering wheel sensor, the G and yaw rate sensor and brake fluid pressure sensor (Refer to Testing and Inspection, Testing and Inspection and Testing and Inspection).

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

- 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

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)

- MB991827: M.U.T.-III USB Cable

- MB991910: M.U.T.-III Main Harness A

STEP 1. DTC check

Use scan tool to check the DTC for the ASC system. (Refer to Active Stability Control System (ASC).)

Q. Is the check result normal?

YES Go to Step 2.
NO Troubleshoot for the relevant DTC (Refer to Active Stability Control System (ASC)).
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 Active Stability Control System (ASC)).

Q. Is the check result normal?

YES Go to Step 3.
NO Connect the brake tubes correctly, repair the external brake lines, or replace the hydraulic unit (integrated with ASC-ECU) (Refer to Active Stability Control System (ASC)).
STEP 3. Brake operation check

Perform the following checks.

- Brake pedal check Brake Pedal Check and Adjustment).

- Brake booster check Testing and Inspection).

- Check valve check Testing and Inspection).

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 (Refer to Actuator Test Reference Table).

- 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?

YES The procedure is complete.
NO Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Active Stability Control System (ASC)).