Itg is the transfer case control module 100% sure just replaced someones module.. you can pick one up for $20 and up from a junk yard it is located in the truck , on passenger side kick panel 3 bolts unplug then plug in new one.. rebolt on new one, replace kick panel and floor sill panel... done , then it will work.. Less than 10 minutes of work, if they say it takes longer they are lying.. You dont really need the OBD 2 to figure out a common problem.. If you ever had heater core problems or replacement the water ruined the module or it is corroded. Happy Motoring!!
Source: Exoerience and common sense!!