Inspection Procedure 1: The Communication Between M.U.T.-III and AS&G-ECU Not Possible


OPERATION



  • The battery voltage is supplied to the diagnosis connector (terminal No. 16) from the ETACS-ECU (C-417 ETACS-ECU connector terminal No. 8).
  • The diagnosis connector (terminal No. 4 and terminal No. 5) is earthed to the vehicle body.

COMMENT ON TROUBLE SYMPTOM



  • When the communication between M.U.T.-III and the AS&G-ECU is impossible, the CAN bus line, power supply circuit of the diagnosis connector, and/or earthing circuit could possibly be defective. The communication cannot be achieved either if the wrong vehicle type is selected on M.U.T.-III.

PROBABLE CAUSES



  • Open/short circuit or harness damage in the diagnosis connector circuit or loose connector contact
  • Failed CAN communication
  • Failed M.U.T.-III
  • Failed ETACS-ECU
  • Failed AS&G-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the Vehicle Communication Interface (V.C.I.) operations.

  • Connect the M.U.T.-III to the diagnosis connector.
  • Turn ON the power of the Vehicle Communication Interface (V.C.I.).
OK: The indicator lamp of the Vehicle Communication Interface (V.C.I.) illuminates in green.

Q. Is the check result normal?
Go to Step 11.
Go to Step 2.

STEP 2. Check battery.

  • Check battery (Refer to GROUP 54A - Battery - On-vehicle Service - Battery Test ).

Q. Is the check result normal?
Go to Step 3.
Replace the battery.

STEP 3. Connector check: C-227 diagnosis connector

Q. Is the check result normal?
Go to Step 4.
Repair or replace the connector.

STEP 4. Perform voltage measurement at C-227 diagnosis connector.

  • Voltage between terminal No. 16 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 7.
Go to Step 5.

STEP 5. Connector check: C-417 ETACS-ECU connector

Q. Is the check result normal?
Go to Step 6.
Repair or replace the connector.

STEP 6. Check harness between C-417 (terminal No. 8) ETACS-ECU connector and C-227 (terminal No. 16) diagnosis connector.

  • Check power supply line for open/short circuit.

Q. Is the check result normal?
Check ETACS-ECU power supply circuit (Refer to GROUP 54A - ETACS - Symptom Procedures - Malfunction of ETACS-ECU Power Supply Circuit ).
Repair the damaged harness wire.

STEP 7. Perform resistance measurement at C-227 diagnosis connector.

  • Resistance between terminal No. 4 and earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?
Go to Step 8.
NO <L.H. drive vehicles> :
NO <R.H. drive vehicles> :

STEP 8. Perform resistance measurement at C-227 diagnosis connector.

  • Resistance between terminal No. 5 and earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?
Go to Step 9.
NO <L.H. drive vehicles> :
NO <R.H. drive vehicles> :

STEP 9. Connector check: C-417 ETACS-ECU connector

Q. Is the check result normal?
Go to Step 10.
Repair or replace the connector.

STEP 10. Check harness between C-417 (terminal No. 8) ETACS-ECU connector and C-227 (terminal No. 16) diagnosis connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Refer to the M.U.T.-III reference manual.
Repair the damaged harness wire.

STEP 11. M.U.T.-III CAN bus diagnosis

  • Use M.U.T.-III to perform CAN bus line diagnosis.

Q. Is the check result normal?
Check AS&G-ECU Power Supply, Ignition Switch-IG1 System (Refer to ).
Repair CAN bus line (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnostics Table ).