Inspection Procedure 1: Scan Tool Communication With ABS/ASC System Is Impossible

Inspection Procedure 1: Scan tool Communication with ABS/ASC system is Impossible.

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.
^ If the power is supplied with the ground circuit of CAN communication device open circuited, an electric potential abnormality may occur to the CAN bus lines.
^ 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
When scan tool cannot communicate with the ABS/ASC system, the CAN bus lines, ASC-ECU power supply circuit system, ground, or ASC-ECU may be faulty.

PROBABLE CAUSES
^ Damaged wiring harness and connectors
^ ASC-ECU malfunction
^ Wrong routing of scan tool harness
^ Abnormality in battery or alternator
^ Abnormality in power supply voltage to ASC-ECU
^ ECU malfunction of other system

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

Scan tool CAN bus diagnosis
Use scan tool to diagnose the CAN bus lines.

Q: Is the check result normal?
YES: Check the power supply circuit, and repair if necessary.
NO: Repair the CAN bus lines.