totally at a loss.....need some help!!!

[hoorders]

Ok.........here is the quick run down of events. My truck is a 2000 Z71 with auto-trac.

 

1. Lubing my truck a few weeks ago and while I was under it I noticed I could not turn the front drive shaft by hand to get at the u-joint.

 

2. At around the same time my 'service 4wd' had been coming on and off for a few weeks.

 

3. I pull my front diff actuator out to have a look at it.....and the plunger is in the 'out' or 'engaged' poistion. I play with my dash 4x4 switch from 2wd to 4wd and the actuator does not change position.....I can hear the transfer case switching back and forth but no change in the actuator.

 

4. I buy a new dash 4x4 switch as I know these are prone to fail and still same problem with actuator.

 

5. I buy a new actuator and still it won't disengage and engage as I switch from 2wd to 4wd.

 

 

So...........what to do?...............what signals the actuator?????

 

Does the actuator actaully have to be in the front diff for it to work or should it still respond even out of the diff with the wire harness plugged into it of course????

 

Can someone shed some light on this???...............it would certainly be really appreciated.

 

Has anyone had their actuator out of their diff and switched from 2wd to 4wd to see if it reacts??

 

Thanks everyone!!.............