Inspection Procedure 1: Communication with Engine-ECU Is Not Possible

OPERATION

The M.U.T.-III receives data from the engine-ECU via the CAN bus line.

PROBABLE CAUSES

Damaged connector (Engine-ECU connector, diagnosis connector)
Damaged harness (Open or short circuit in the engine-ECU power supply circuit, open circuit between diagnosis connector and J/B connector, and open circuit between diagnosis connector and earth)
Failed CAN bus line
Failed M.U.T.-III
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the V.C.I. indicator lamp illuminates.

Connect the M.U.T.-III to the diagnosis connector.

Q. Is the V.C.I. indicator lamp illuminates in a green colour?

CAN bus diagnosis (Refer to GROUP 54C - Troubleshooting - Can Bus Diagnosis Table

).

Go to Step 2 .

STEP 2. Connector check: C-22 diagnosis connector

Q. Is the check result normal?

Go to Step 3 .

Repair or replace.

STEP 3. Perform voltage measurement for open circuit at C-22 diagnosis connector.

Voltage between terminal No. 16 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 4 .

Repair harness between C-22 (terminal No. 16) diagnosis connector and C-208 (terminal No. 13) J/B connector.

STEP 4. Check for open circuit between diagnosis connector C-22 and earth.

Disconnect connector.
Check open circuit between terminal No. 4 and earth also between terminal No. 5 and earth.

Q. Is the check result normal?

Refer to M.U.T.-III User’ s Manual - Troubleshooting Procedures.

Repair harness between diagnosis connector and body earth.