We solved the hub engagement problem by replacing the vacuum switch (not sure if you call it a switch, little plastic thingy that the lines go into) under the hood, it was full of crud. If it's something simple let me know! I suspect my problem has something to do with the ECM, if that's not working right it will manifest itself in all kinds of odd ways. Before the 4wd quit working it would shift in and out on it's own. I'm looking for a wiring diagram so we can start eliminating some things.