Inspection Procedure 12: ASC System Does Not Operate or Faulty ASC Operate.

INSPECTION PROCEDURE 12: ASC system does not operate or faulty ASC 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 (Refer to Trouble code diagnosis Diagnosis).
^ 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, ASC system operation may be disabled. Diagnostic trouble code may be set by the TCL/ASC system using 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

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 Diagnostic Trouble Code Descriptions.)
Q: Is the check result normal?
YES: Go to Step 2.
NO: Carry out the diagnosis for the DTC. (Refer to Diagnostic Trouble Code Descriptions.)

STEP 2. Engine control module coding data check
Using scan tool, check if any abnormality is present to the coding data below which are stored in the engine control module.
A.S.C.
OK: Available
Q: Is the check result normal?
YES: Go to Step 4.
NO: Go to Step 3.

STEP 3. Engine ECU coding data check
Perform the variant coding to the Engine ECU.
Q: Is the check result normal?
YES: Go to Step 5.
NO: Replace the engine control module. Then go to Step 5.

STEP 4. 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 Traction Control/Active Skid Control System (TCL/ASC).)
Q: Is the check result normal?
YES: Replace the hydraulic unit (integrated with ASC-ECU). Then go to Step 5.
NO: Connect the brake tubes correctly, and repair or replace the external brake lines of the hydraulic unit (integrated with ASC-ECU).

STEP 5. 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.