Diagnostic Test

Ignition on, engine not running.

With the scan tool, read DTCs in the Transmission Control Module.

Are there any DTCs present? 

Yes 

1. Refer to the appropriate symptom list and perform the applicable diagnostic procedure. Refer to appropriate Transmission ELECTRICAL DIAGNOSTICS article.
2. Perform TRANSFER CASE VERIFICATION TEST .

No 

1. Replace the Final Drive Control Module in accordance with the Service Information.
2. Perform TRANSFER CASE VERIFICATION TEST .