Inspection Procedure 1: M.U.T.-III communication with ABS/ASC system is impossible.

  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
  • If the power is supplied with the earth circuit of CAN communication device open circuited, an electric potential abnormality may occur to the CAN bus lines.


When M.U.T.-III cannot communicate with the ABS/ASC system, the CAN bus lines, ASC-ECU power supply circuit system, earth, or ASC-ECU may be faulty.


  • Damaged wiring harness and connectors
  • ASC-ECU malfunction
  • Wrong routing of M.U.T.-III harness
  • Abnormality in battery or alternator
  • Abnormality in power supply voltage to ASC-ECU
  • ECU malfunction of other system

M.U.T.-III CAN bus diagnosis

Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

Check the power supply circuit, and repair if necessary (Refer to ).
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).