Inspection Procedure 1: Communication with Engine-ECU is Not Possible
OPERATION
- Battery voltage is applied to the diagnosis connector terminal.
- The diagnosis connector terminal is earthed to the vehicle body.
COMMENTS ON TROUBLE SYMPTOM
- When the communication between M.U.T.-III and the engine-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
- Defective diagnosis connector
- Open/short circuit or harness damage in diagnosis connector circuit or loose connector contact
- Defective CAN communication
- Defective M.U.T.-III
- Failed engine-ECU
|
|
STEP 1. Check the Vehicle Communication Interface (V.C.I.) operations
|
|
|
- Connect the M.U.T.-III to the diagnosis connector.
- When the power of Vehicle Communication Interface (V.C.I.) is turned to ON, the indicator lamp of the Vehicle Communication Interface (V.C.I.) illuminates in green.
|
|
|
OK: The indicator lamp of the Vehicle Communication Interface (V.C.I.) illuminates in green.
|
|
|
Q.
Is the check result normal?
|
|
|
 Go to Step 10.
|
|
|
|
|
|
 Go to Step 2.
|
|
|
|
|
|
- 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. Voltage measurement at diagnosis connector (MUT line).
|
|
|
(1)Check the voltage between the diagnosis connector (MUT line) and body earth.
OK: System voltage
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 6.
|
|
|
|
|
|
Go to Step 4.
|
|
|
|
|
|
STEP 4. Continuity check on ETACS-ECU connectors
|
|
|
(1)Disconnect the connector, and measure at the ETACS-ECU side.
|
|
|
(2)Continuity check between terminal +B1 and MUT
OK: Continuity
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 5.
|
|
|
|
|
|
Check fuse in the ETACS-ECU, and replace if necessary. If the fuse is normal, replace the ETACS-ECU.
|
|
|
|
|
|
STEP 5. Check of open circuit and short to earth in +B1 line between battery and ETACS-ECU connector.
|
|
|
Q.
Is the check result normal?
|
|
|
Repair MUT line between ETACS-ECU connector and diagnosis connector.
|
|
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
|
|
STEP 6. Resistance measurement at diagnosis connector (body earth lines)
|
|
|
(1)Measure the resistance between the diagnosis connector (body earth lines) and body earth.
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 7.
|
|
|
|
|
|
Repair body earth lines between diagnosis connector and body earth.
|
|
|
|
|
|
STEP 7. Continuity check on ETACS-ECU connectors
|
|
|
(1)Disconnect the connector, and measure at the ETACS-ECU side.
|
|
|
(2)Continuity check between terminal +B1 and MUT
OK: Continuity
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 8.
|
|
|
|
|
|
Check fuse in the ETACS-ECU, and replace if necessary. If the fuse is normal, replace the ETACS-ECU.
|
|
|
|
|
|
STEP 8. Check of damage in +B1 line between battery and ETACS-ECU connector.
|
|
|
Q.
Is the check result normal?
|
|
|
Go to Step 9.
|
|
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
|
|
STEP 9. Check of damage in MUT line between ETACS-ECU connector and diagnosis connector connector.
|
|
|
Q.
Is the check result normal?
|
|
|
Refer to the M.U.T.-III reference manual.
|
|
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
|
|
STEP 10. M.U.T.-III CAN bus diagnosis
|
|
|
- Use M.U.T.-III, perform CAN bus line diagnosis.
|
|
|
Q.
Is the check result normal?
|
|
|
Check engine-ECU power supply system (Refer to ).
|
|
|
|
|
|
Perform troubleshooting for CAN (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnostics Table ).
|
|
|
|