01 blazer
 

If anyone can shed some light, I would appreciate it. The front axle will not engage. It has the Vac. actuator under the battery, Its working fine. the cable coming down to the case is good. The actuator at the case(three pin) screw in type. Put it on the rack today, put in 4 wheel high...click click click click...but would not engage. you could feel the heavy clicking noise in your hand. I'm just trying to figure out if the case actuator is bad or the motor is bad or both. unplugged the three pin connector, still click click click no change. Any help,I would appreciate it.

Pull on the cable yourself and lock it in if you can. If you cannot, then there is a problem internal to the axle which will require the removal of the passenger side axle extension tube.

Thanks for the input. I pulled the cable and locked it down with vise grips and no cigar. Any idea what has failed??

Check out this thread:
S-10 4WD question long

As well as THIS POST.