Inspection Procedure 11: ASC Does Not Operate or Faulty ASC Operate

Inspection Procedure 11: ASC does not Operate or Faulty ASC Operate.

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.
^ 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.

COMMENTS ON TROUBLE SYMPTOM
In case of this trouble symptom, the skid control/TCL system operation may be disabled. DTC may be set by the skid control/TCL system using scan tool.

PROBABLE CAUSES
^ Low battery output
^ Wiring harness or connector failure of CAN bus line
^ ASC-ECU malfunction
^ Engine coding data problem

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.

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

STEP 2. Engine ECU coding data check
Using scan tool, check if any abnormality is present to the coding data below which are stored in the ECM.
A.S.C.
OK: Available

Q: Is the check result normal?
YES: Go to Step 3.
NO: Replace the engine ECU. 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).

Q: Is the check result normal?
YES: Replace the hydraulic unit (integrated with ASC-ECU). 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 skid control/TCL operate normally?
YES: The procedure is complete.
NO: Check the brake system related components other than the skid control/TCL system.