Inspection and Verification

Inspection and Verification
1. Verify the customer concern.
2. Inspect for obvious signs of mechanical or electrical damage.

Visual Inspection Chart

Visual Inspection Chart:

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 vehicle communication module (VCM) LED prove out confirms power and ground from the DLC are provided to the VCM.

If the scan tool does not communicate with the VCM:
^ check the VCM connection to the vehicle.
^ check the scan tool connection to the VCM.
^ refer to Information Bus, No Power To The Scan Tool, to diagnose no communication with the scan tool.
6. If the scan tool does not communicate with the vehicle:
^ verify the ignition key is in the ON position.
^ refer to Information Bus to diagnose no response from the PCM.
7. Carry out the network test.
^ If the scan tool responds with no communication for one or more modules, refer to Information Bus.
^ If the network test passes, retrieve and record continuous memory DTCs.
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. For all other DTCs, refer to Body Control Systems. Diagnostic Trouble Code Tests and Associated Procedures
10. If no DTCs related to the concern are retrieved, GO to Symptom Chart - Four Wheel Drive System. Symptom Related Diagnostic Procedures