I have a 2011 Citadel that is having a similar issue. Mine is an AWD, but it get the Service Four Wheel Drive System message upon start up. It also says ACC / FCW Unavailable Vehicle System Error. The SERV 4WD light comes on along with the traction control off light. As a result, my cruise will not work. The vehicle drives fine and there are no leaks or abnormal sounds. I cannot shift it into 4 Low either. Seems to me its something electrical, but the one shop I took it to said it could take hours to diagnose. Just wondering if anyone else has ran into this issue?