Inspection Procedure 10

Inspection Procedure 10: Skid control/TCL does not operate.

CAUTION:

- If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines Initial Inspection and Diagnostic Overview ).
- Whenever the ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit (integrated with ASC-ECU) is replaced, always perform the calibration of steering wheel sensor, G and yaw rate sensor, brake fluid pressure sensor, cut valve, and inlet valve (Refer to G and Yaw Rate Sensor Calibration , Testing and Inspection , Master Cylinder Brake Fluid Pressure Sensor Calibration , and Testing and Inspection ).

TECHNICAL DESCRIPTION (COMMENT)

In case of this trouble symptom, the operation of skid control/TCL system may be disabled. In this case, a diagnostic trouble code may be set by the skid control/TCL system using the scan tool.

PROBABLE CAUSES

- Low battery output
- Wiring harness or connector failure of CAN bus line
- ASC-ECU malfunction
- Different ETACS-ECU, abnormal variant coding information
- Abnormal engine coding data

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 DTC.

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

Q. Is the check result normal?

YES Go to Step 2.
NO Carry out the diagnosis for the DTC (Refer to Active Stability Control System (ASC)).
STEP 2. Engine control module coding data check

Using the scan tool, check if there is any abnormality to the following coding data stored in the engine control module Programming and Relearning).

A.S.C.

OK: Present


Q. Is the check result normal?

YES Go to Step 3.
NO Replace the engine control module Removal and Replacement). Then go to Step 4.
STEP 3. Hydraulic unit (integrated with ASC-ECU) check

Check that the brake tube is correctly mounted to the hydraulic unit (integrated with ASC-ECU) (Refer to Electronic Time and Alarm Control System (ETACS)).

Q. Is the check result normal?

YES Replace the hydraulic unit (integrated with ASC-ECU) (Refer to Testing and Inspection). Then go to Step 4.
NO Connect the brake tubes correctly, and repair or replace the external brake lines of the hydraulic unit (integrated with ASC-ECU).
STEP 4. Operation check

Q. Does the skid control/TCL operate normally?

YES The procedure is complete.
NO Check the brake related components other than the skid control/TCL.