4x4 turn knob

[An 8th Day Production]

Don't know if posting in right area or not.

I have a 2013 GMC Sierra SLE 

Noticed today that the little led light on the 4x4 knob was not on. When you turn the key to aux power on the light comes on over the 2wd position. When you start the truck a red N flashes then all lights go off. The switch does nothing if you turn it. There is no service 4x4 message. 

I havent seen any other issues like this online.

 

[Colossus]

You won't see a service 4X4 message.  there likely is a code though in the system.  It's either 2 things.  The switch is bad, and/or the transfer case is shot.