Inspection Procedure 1: Scan tool MB991958 cannot Communicate with the Electronic Control AWD System: Diagnosis
- STEP 1. Scan tool MB991958 CAN bus diagnostics
Use scan tool MB991958 to diagnose the CAN bus lines.
Q: Is the check result normal?
YES : Go to Step 2.
NO : Repair the CAN bus line (Refer to DIAGNOSIS <CAN> ). On completion, Go to Step 2.
- STEP 2. Check the following connector:
Check the connectors below for improper engagement, terminal damage or terminal drawn in the connector case.
- C-228 AWD-ECU connector
- C-408, C-412, C-415 ETACS-ECU connector
Q: Are the connectors and terminals in good condition?
YES : Go to Step 3.
NO : Repair the connector(s) or terminal(s). Then Go to Step 8.
- STEP 3. Voltage measurement at the AWD-ECU connector
- Disconnect the C-228 AWD-ECU connector.
- Turn the ignition switch to the "ON" position.
- Measure the voltage between the C-228 wiring harness side connector terminals No. 3, No. 4 (Ignition switch "ON") and the body ground.
OK: System voltage
Q: Is the check result normal?
YES : Go to Step 5.
NO : Go to Step 4.
- STEP 4. Wiring harness check
Check the wiring harness between the C-228 AWD-ECU connector (terminal No. 4) and the C-412 ETACS-ECU connector (terminal No. 2) for damage or other problem.
Q: Is the wiring harness in good condition?
YES : Go to Step 7.
NO : Repair the wiring harness. Then Go to Step 8.
- STEP 5. Resistance measurement at the AWD-ECU connector
- Disconnect the C-228 AWD-ECU connector.
- Measure the resistance between the C-228 wiring harness side connector terminals No. 10 and the body ground.
OK: Continuity exists (2 ohm or less)
Q: Is the check result normal?
YES : Go to Step 7.
NO : Go to Step 6.
- STEP 6. Wiring harness check
Check the wiring harness between the C-228 AWD-ECU connector (terminal No. 10) and the body ground for damage or other problem.
Q: Is the wiring harness in good condition?
YES : Go to Step 7.
NO : Repair the wiring harness. Then Go to Step 8.
- STEP 7. Retest the system.
Q: Does the malfunction occur again?
YES : Replace AWD-ECU (Refer to RESISTANCE MEASUREMENT BETWEEN ELECTRONIC CONTROL COUPLING SOLENOID CONNECTOR TERMINALS ). Then Go to Step 8.
NO : The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
- STEP 8. Retest the system.
Q: Does the malfunction occur again?
YES : Diagnose again from Step 1.
NO : The procedure is complete.