1997 4WD problems

I have a 1997 Jimmy that the 4 WD stopped working. It is an automatic push button activation. The indicator lights indicates that it shifts to 4 WD but there is no power to the front axel. When the rear wheels spin in the snow I can hear a grinding sound under the vehicle. Almost like something is not fully engaging in the transfer case. I have replaced the vacuum switch on the transfer case. I have also checked and tested the vacuum actuator under the battery, this seems to be working properly. Could the encoder motor cause this problem or should I be looking somewhere else?

97 4wd problems, most problems are caused by the transfer case vac switch failing this lets fluid into the entire vacuum system and then the fun begins.You should have a np233 transfer case (solid case) so I would look at vacuum first.Autozone has a alldatadiy program that is (30$year)Outstanding!! most fault codes will display from 4wd switch on dash,must have.good look my brother this car is worse than a sharp stick in the eye