1999 4x4 T-10 Blazer 4x4/tranny shift problem

I own a 1999 Blazer in which all the push button 4x4 lights light up and the service 4x4 light comes on. When this happens it loses power and wont shift. If you unplug the push buttons, it should default to 4hi. (and not act up) I did this and mine didn't default to 4hi and acted the same. This is surely a sign of a faulty tccm. Although I am not certain. Could anyone shed some light on this problem?.

Jordan.