Edwin McGraw

I have a 2015 GMC Sierra 1500 with 37000 mi. getting stuck in 4wd low. been to dealer and they reprogramed computer about 1year ago. Under warranty. Now at dealer with same problem no longer under warranty. Dont think there is a fix. This time it reset itself before I got to dealer. Still left it so they can look at it. This is going to be a on going problem I think. Is there away to get this to reset. All lights on selector switch go off and service 4w indication comes on. Need advice .Thanks