Archived 4x4 not working

[KIKER]

A friend of mine is driving a '14 3500 dually 4x4 as a welding truck. He just called and said he got stuck in the sand and his 4x4 wouldn't work. He had a check engine light and abs light showing on the dash. He has manual shift transfer case and I told him the computer couldn't bypass the manual shifting but remembered the front axle has an axle disconnect to improve fuel economy. Would having those MIL active defeat the 4 wheel drive? He got out and is going to make a trip to the dealer on Monday. The truck is a 6.4 Hemi and not a Cummins, but I don't think that would make any difference.