hello and welcome to just answer.To reprogram the 4x4 module requires a TECH2 scanner and access to SPS on gm dealerworld.Here is the reprogram procedure.
Transfer Case Shift Control Module Reprogramming Set-up for Module Programming/Reprogramming
Important: Ensure that the vehicle battery is fully charged and that a battery charger is no longer connected. If performing this procedure for module replacement, install new module before proceeding. Before reprogramming close the doors and wait two minutes to allow other modules to stop communicating via the class 2 data line. Failure to due so could result in a failed reprogramming procedure.
When replacing an electronic control unit (ECU) the Scan Tool Pass-Through Connection procedure may be required to be performed in order to initiate communication with the ECU.
Programming Using Scan Tool Pass-Through Connection
Remote Programming Feature