front axle engagement

how do you disengage my front diff on my 1995 GMC sierra , it seems to still be engaged when it is not in four wheel drive. ive tried backing up but it didnt work.

The front axle is enguaged by an accuator on the front axle. If it is stick out then the front diff will be enguaged.

I had read somewhere that the actuator system can stop
recognizing it's position and can be reset by a fuse pulling
procedure. I wish I had more info. I'll try to find where I
saw this.