Inspection and Verification

Inspection and Verification
1. Verify the customer concern.
2. Visually 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 (Module Communications Network), No Power To The Scan Tool, to diagnose no communication with the scan tool.

6. NOTE: Before carrying out the self-test, make sure that:
^ verify the ignition key is in the ON position.
^ refer to Information Bus (Module Communications Network) to diagnose no response from the powertrain control module (PCM).

If the scan tool does not communicate with the vehicle:
^ verify the ignition key is in the ON position.
^ refer to Information Bus (Module Communications Network) to diagnose no response from the powertrain control module (PCM).
7. Carry out the network test.
^ If the scan tool responds with no communication for one or more modules, refer to Information Bus (Multiplex Communications Network).
^ If the network test passes, retrieve and record continuous memory diagnostic trouble codes (DTCs).
8. Clear the DTCs and carry out the self-test diagnostics for the 4WD control module.

9. NOTE: Before carrying out the on-demand self test, make sure that:
^ the ignition is in RUN.
^ all doors are closed.
^ the brake pedal is not pressed.
^ the transmission is not in NEUTRAL.

If the DTCs retrieved are related to the concern, go to the Four Wheel Drive (4WD) Control Diagnostic Trouble Code (DTC) Chart. For all other DTCs, refer to Body Control Systems (Multifunction Electronic Control Module). Late Build
10. If no DTCs related to the concern are retrieved, GO to Symptom Chart. Late Build