Spray insert of a large crock pot with non-stick spray. Place pork roast inside. Pour 8 ounces of Coca-Cola and water all around pork. (It does not need to cover roast) Sprinkle evenly with garlic salt, salt and pepper. Cover with lid and cook on High heat for 6 hours, or on Low heat 8 to 9 hours.
Remove pork from crock pot and transfer to cutting board. Discard liquid from crock pot. Shred pork with two forks, and remove any fat.
In a blender or food processor, blend the remaining 8 ounces Coca-Cola, diced green chilies, enchilada sauce and brown sugar. Blend until smooth.
Place shredded pork back in crock pot. Pour enchilada sauce mixture over the shredded pork. Cover crock pot with lid and cook another 1 to 2 hours on Low heat or until heated through. Serve and enjoy!