Inspection and Verification

Four Wheel Drive (4WD) Systems

Inspection and Verification

1. Verify the customer concern.

2. Inspect for obvious signs of mechanical or electrical damage.







3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

4. NOTE: Make sure to use the latest scan tool software release.

If the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC).

5. NOTE: The LED prove out confirms power and ground from the are provided to the VCM.

If the scan tool does not communicate with the VCM:

- check the connection to the vehicle.

- check the scan tool connection to the VCM.

- refer to Module Communications Network Testing and Inspection, No Power To The Scan Tool, to diagnose no power to the scan tool.

6. If the scan tool does not communicate with the vehicle:
- verify the ignition is ON (RUN).
- The air bag warning indicator prove-out (other indicators may not prove ignition is ON) confirms the ignition is ON (RUN). If the ignition does not turn ON, refer to Steering Column Switches Testing and Inspection to diagnose no power in ON (RUN).

- refer to to diagnose no response from the PCM.

- verify the scan tool operation on a known good vehicle.

7. Carry out the network test.
- If the scan tool responds with no communication for one or more modules, refer to Module Communications Network Testing and Inspection.

- If the network test passes, retrieve and record Continuous Memory Diagnostic Trouble Codes (CMDTCs).

8. Clear the DTCs and carry out the self-test diagnostics for the 4X4 control module.

9. If the DTCs retrieved are related to the concern, go to the 4X4 Control Module DTC Chart Diagnostic Trouble Code Tests and Associated Procedures. For all other DTCs, refer to Multifunction Electronic Modules Diagnostic Trouble Code (DTC) Chart.

10. If no DTCs related to the concern are retrieved, GO to Symptom Chart. Four Wheel Drive (4WD) Systems