GM-GMC: 4wd, allison transmissions, case problem

Question
I have a 2500 duramax dissel 6.6 The 4wd just quit
working,disconnected battery to reset computer,no
change,removed actuator seems to be working when button is
pushed.dont know what else to do.Thankyou for any help you
can give.

Answer
If the front actuator is working, perhaps the transfer case is not shifting into 4wd.  There is an encoder motor on the side of the transfer case which is responsible for shifting from 2wd to 4wd.  I have seen quite a few transfer cases malfunction, especially on trucks with allison transmissions, which is what I imagine your truck has.  Unfortunately it is almost all electronically controlled system.  There are very few things you can do yourself without a scanner to check the encoder motor function etc.  It sounds like your switch is working and front actuator is working.  From what you have described to me it seems you have a transfer case problem and will need to have it diagnosed by your local dealer.  I really hate saying that to people, but with that type of system you have already done what you can.
Hope this helps