I have a 2008 XLT V6 (not flex fuel if that matters) with nearly 190k on it. The AWD stop working when the car was my parents, and according to them there was no signs, noises, lights, or any warning before it went. It wasnt gradual, just did not work one day. I havent got any codes for it, the awd light still comes on at startup, and when i put the vehicle on a lift only the front driver wheel spun and the driveshaft did not move at all. As far as i know, its either a speed sensor, control module, or transfer case issue, but I have no clue how to continue diagnosing at this point. Has anyone had similar problems, or any information on the testing of these component or how they should normally operate? Its hard to find operation and specs on them. Id just like to figure out what the issue is myself so i dont have to pay a ridiculous amount to go to a dealer and get it diagnosed, since I can likely fix it myself anyway.