Inspection and Verification

WARNING: This page is about a different variant/trim than selected.

Visually inspect for obvious signs of mechanical or electrical damage.

VISUAL INSPECTION CHART

Mechanical	Electrical
Halfshafts Integrated Wheel End (IWE) Driveshaft and U-joints Vacuum leaks Fluid leaks Matching tire sizes Transfer case	Battery Junction Box (BJB) fuses: 27 (20A) 29 (20A) Smart Junction Box (SJB) fuse 35 (10A) Transfer Case Control Module (TCCM) Mode Select Switch (MSS) IWE solenoid Wiring harness Connector(s) Circuitry

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

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).

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 MODULE COMMUNICATIONS NETWORK , No Power To The Scan Tool, to diagnose no power to the scan tool.
If the scan tool does not communicate with the vehicle:
- verify the ignition is in the ON position.
- refer to MODULE COMMUNICATIONS NETWORK to diagnose no response from the PCM.
Carry out the network test.
- If the scan tool responds with no communication for one or more modules, refer to MODULE COMMUNICATIONS NETWORK .
- If the network test passes, retrieve and record Continuous Memory Diagnostic Trouble Codes (CMDTCs).
Clear the DTCs and carry out the self-test diagnostics for the TCCM.
NOTE: Before carrying out the on-demand self test, make sure that:
- the ignition is in RUN.
- 2-Wheel Drive (2WD) mode is selected.
  If the DTCs retrieved are related to the concern, go to the Transfer Case Control Module (TCCM) DTC Chart . For all other DTCs, refer to MULTIFUNCTION ELECTRONIC MODULES .
If no DTCs related to the concern are retrieved, GO to SYMPTOM CHART - FOUR WHEEL DRIVE (4WD) or GO to SYMPTOM CHART - NVH .