[davester3500]

Test and see. Could be anywhere between the sensor in the transfer case to the actuator.

Perhaps start with making sure the transfer case is shifting into 4wd?

 

[davester3500]

So, you've removed the actuator from the front axle, plugged it in, and shifted between 2wd and 4wd, and it's not extending, either with the new actuator or the original one?