Inspection Procedure 1: Communication with the M.U.T. is not possible <4M4>












COMMENTS ON TROUBLE SYMPTOM


Failure may occur on power supply circuit of A/T-ECU and diagnosis connector, and earth circuit.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III communication check
(1)Connect the M.U.T.-III to the diagnosis connector.
(2)Turn the ignition switch to the ON position.

Q. Is the communication with the other systems possible?
Go to Step 8.
Go to Step 2.

STEP 2. Connector check: D-127 diagnosis connector.
Check for the contact with terminals.

Q. Is the check result normal?
Go to Step 3.
Repair the defective connector.

STEP 3. Measure the resistance at diagnosis connector D-127.
Measure the resistance between terminal No.4, 5 and earth at the wiring harness side.

Q. Is the check result normal?
Go to Step 5.
Go to Step 4.

STEP 4. Check the harness between diagnosis connector D-127 terminal No.4, 5 and earth.
Check the earth line for open circuit.

Q. Is the check result normal?
Go to Step 6.
Repair the wiring harness.

STEP 5. Measure the voltage at diagnosis connector D-127.
Measure the voltage between diagnosis connector D-127 terminal No.16 and earth.
OK: System voltage

Q. Is the check result normal?
Replace the M.U.T.-III.
Go to Step 6.

STEP 6. Connector check: D-404, D-405 J/B connector.
Check for the contact with terminals.

Q. Is the check result normal?
Go to Step 7.
Repair the defective connector.

STEP 7. Check the harness between diagnosis connector D-127 terminal No.16 and J/B connector D-404 terminal No.1.
Check the power supply line for short or open circuit.

Q. Is the check result normal?
Go to Step 8.
Repair the wiring harness.

STEP 8. M.U.T.-III CAN bus diagnosis
Using M.U.T.-III, perform CAN bus line diagnosis.

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Repair the CAN busline (Refer to GROUP 54D - Troubleshooting ).