4 Wheel Drive/SUVs: 4x4 not working, ill family member, gm dealer

Question
I have a 2006 GMC Envoy. when i switch over to the 4x4 i hear a whining noise under the car but it doesn't engage.. The light blinks and then stays solid, worked before the got it stuck in the snow last year.. please any suggestions..

Answer
Robin, sorry for the delay I have had an ill family member so I wasnt able to get back to you right away .  The 4x4 system in these envoys and Trailblazers are very tempermental at times . We just had one in the shop last week and ended up having to take it in to the Gm dealer to get the system reprogramed on it, thats what I am guessing should be your first step. I think it costs about $85 or so to do it, but they will run a complete diagnostic check on your 4x4 system so that would be well worth your time thanks ADAM