Inspection Procedure 13

Inspection Procedure 13: ABS/skid control/TCL operates too frequently.

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 Line Diagnostics Flow).

- 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 diagnostic trouble code is not detected.

- If wheels and tires other than the ones with genuine specified size are mounted, the ABS/skid control/TCL may be activated prematurely.

- If a non-genuine braking device or non-genuine impact reduction device is mounted, the ABS/skid control/TCL may be activated prematurely.

PROBABLE CAUSES

- Mounting of wheels and tires other than with genuine specified size

- Tire pressure abnormality

- Tire wear and deterioration

- Mounting of non-genuine braking device or impact reduction device

- Wheel alignment abnormality

- Malfunction of brake related parts

- Malfunction of the wheel speed sensor

- Malfunction of the G and yaw rate sensor

- Steering wheel sensor malfunction

- Malfunction of hydraulic unit (integrated with ASC-ECU)

- Malfunction of hydraulic circuit

- External radio wave noise interference

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. Check the wheels and the tires.

Carry out the following check.

- Size check of wheels and tires

- Tire wear and deterioration statuses

- Check the tire pressure.
NOTE:
For the tire pressure, refer to the tire pressure label attached to the lower section of driver's side door striker.

Q. Is the check result normal?

YES Go to Step 2.
NO Correct the wheels and tires in good condition. Then go to Step 9.
STEP 2. Diagnostic trouble code check

Use scan tool MB991958 to check the diagnostic trouble code for the ASC system (Refer to Active Stability Control System (ASC)).

Q. Is the check result normal?

YES Go to Step 3.
NO Carry out the diagnosis for the diagnostic trouble code. (Refer to Active Stability Control System (ASC).) Then go to Step 9.
STEP 3. Check of brake system related components other than hydraulic unit (integrated with ABS-ECU)

At the same time with the following checks, also check that no parts other than the genuine parts are mounted.

- Brake pad check Brake Pad Check).

- Brake disc runout check Brake Disc Check).

- Brake drag force check Brake Drag Force Check).

Q. Is the check result normal?

YES Go to Step 4.
NO Repair or replace the part(s) having damage or other problems. Then go to Step 9.
STEP 4. Wheel alignment check

At the same time with the following checks, also check that no parts other than the genuine parts are mounted.

- Front wheel alignment check Front Suspension).

- Rear wheel alignment check Rear Suspension).

Q. Is the check result normal?

YES Go to Step 5.
NO Repair or replace the part(s) having damage or other problems. Then go to Step 9.
STEP 5. Wheel speed sensor check

Check that no non-genuine electronic device or no wiring harness of other than genuine electronic device is mounted near the wheel speed sensor (at wheel speed detection section and wiring harness section) (Refer to Active Stability Control System (ASC)).

Q. Is the check result normal?

YES Go to Step 6.
NO Remove the non-genuine electronic device or the wiring harness of non-genuine electronic device. Then go to Step 9.
STEP 6. M.U.T.-III data list

Check the following data list (Refer to Data List Reference Table).

- Item 01: FL wheel speed sensor

- Item 02: FR wheel speed sensor

- Item 03: RL wheel speed sensor

- Item 04: RR wheel speed sensor

- Item 08: Lateral G-sensor

- Item 11: Steering angle sensor

- Item 12: Yaw rate sensor

Q. Is the check result normal?

YES Go to Step 7.
NO (Abnormality with items 01 to 04) : Check the installation status of corresponding wheel speed sensor (Refer to Active Stability Control System (ASC)).
NO (Abnormality with items 08, 12) : Check the installation status of G and yaw rate sensor (Refer to Service and Repair).
NO (Abnormality with item 11) : Check the installation status of steering wheel sensor (Refer to Service and Repair).
STEP 7. Hydraulic unit check

Carry out the following actuator tests, and check if they work normally (Refer to Actuator Test Reference Table).

- Item No. 01: FL wheel ABS

- Item No.02: FR wheel ABS

- Item No.03: RL wheel ABS

- Item No.04: RR wheel ABS

- Item No.05: FL wheel TCL

- Item No.06: FR wheel TCL

- Item No.07: RL wheel TCL

- Item No.08: RR wheel TCL

Q. Is the check result normal?

YES Go to Step 8.
NO Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Active Stability Control System (ASC)).
Then go to Step 9.
STEP 8. ABS/skid control/TCL operation check

Q. Is the check result normal?

YES Intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Active Stability Control System (ASC)).
Then go to Step 9.
STEP 9. ABS/skid control/TCL operation check

Q. Is the check result normal?

YES The procedure is complete.
NO Return to Step 1.