2014 Silverado Z71 service 4wd message
 

I have a 2014 reg cab Z71 with intermitting service 4wd message
it has 65000 miles on it. I took it to the dealer and they are dumb founded and want to start throwing parts at it hoping they can fix it.
its not my daily driver so I'm not gonna do that.
the 4wd drive modes work perfect when the message isn't on so I think its something simple
any of you had experience with this before?