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INSPECTION PROCEDURE 1: Communication Between Scan Tool (M.U.T.-IIISE) and AWC-ECU Cannot be Established
 
 
 
 
COMMENTS ON TROUBLE SYMPTOM
If scan tool (M.U.T.-IIISE) cannot communicate with the electronically controlled AWC system, the CAN bus lines may have a problem. If the electronically controller AWC system is not in operation (in case of no AWC operation), the AWC-ECU power supply circuit system or AWC-ECU may have a problem.
 
 
PROBABLE CAUSES
  • Damaged wiring harness and connectors
  • AWC-ECU malfunction
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB992006: Extra fine probe
STEP 1. Scan tool (M.U.T.-IIISE) CAN bus diagnostics
Use scan tool (M.U.T.-IIISE) to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Diagnosis, Can Bus Diagnostics Table ).
 
STEP 2. Voltage measurement at the AWC-ECU connector
(1) Disconnect the AWC-ECU connector.
(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the AWC-ECU wiring harness side connector terminals AWDF, IG16 (Ignition switch "ON") and the body ground.
OK: System voltage
Is the check result normal?
Go to Step 3.
Repair the connector(s) or terminal(s) or wiring harness.
 
STEP 3. Resistance measurement at the AWC-ECU connector
(1) Disconnect the AWC-ECU connector.
(2) Measure the resistance between the AWC-ECU wiring harness side connector terminal GND1 and the body ground.
OK: Continuity exists (2 Ω or less)
Is the check result normal?
Go to Step 4.
Repair the connector(s) or terminal(s) or wiring harness.
 
STEP 4. Retest the system.
Does the malfunction occur again?
Replace AWC-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).