Working on my new project. It's a 2000 blazer with the 4 button 4wd switch.
On the lift with 4hi engaged the front wheels will turn. But when you slightly push the brake pedal the front wheels will stop. Along with the front driveshaft. The rear wheels are still turning as i don't have the pedal completely down.

So why does the front shaft stop while the rear is spinning?
4wd light is illuminated and not flashing.
I checked the 4wd actuator under battery and replace some vac hoses. That's functioning properly.