STEP 1. Check the vehicle communication interface-lite (V.C.I.-Lite) MB992744 operations.
STEP 2. Check the 12V starter battery.
STEP 3. Measure the power supply voltage at data link connector harness side connector.
STEP 4. Check of short to ground and open circuit in MUT line between ETACS-ECU connector and data link connector.
STEP 5. Check of short to ground and open circuit in +B1 line between 12V starter battery and ETACS-ECU connector.
Is the harness wire in good condition?
Check fuse in the ETACS-ECU, and replace as required. If the fuse is in good condition, replace the ETACS-ECU. Then confirm that the malfunction symptom is eliminated. Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
STEP 6. Check the continuity at data link connector harness side connector.
STEP 7. Check the continuity at ETACS-ECU connectors.
(1) Disconnect the connectors and measure at the ETACS-ECU side.
(2) Check for the continuity between terminal +B1 and terminal MUT. Does continuity exist?
Go to Step 8. Check fuse in the ETACS-ECU, and replace as required. If the fuse is in good condition, replace the ETACS-ECU. Then confirm that the malfunction symptom is eliminated.
STEP 8. Check of harness damage in +B1 line between 12V starter battery and ETACS-ECU connector.
STEP 9. Check of harness damage in MUT line between ETACS-ECU and data link connector.
Is the harness wire in good condition?
Refer to the M.U.T.-III SE User's Manual. Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
STEP 10. Using scan tool (M.U.T.-IIISE), diagnose CAN bus line.
(1) Turn on the power supply mode of the electric motor switch.
(2) Diagnose CAN bus line.
(3) Turn off the power supply mode of the electric motor switch.
Is the CAN bus line normal?
Refer to Inspection Procedure - Power Supply System and OSS-ECU (IG1) System . Repair the CAN bus line. Refer to GROUP 54C, Diagnosis - CAN Bus Diagnostics Table . Then confirm that the malfunction symptom is eliminated.