4X4 Problems on 92 Ranger

[hellcat]

Kick in the 4wd system and here the dreaded automatic hubs grind. Made my mind up about going manual. In the meantime I get the 4X4 to engage everything seems to be working fine. During the day I put on a hundred miles or so using the 4X4 several times without a problem. Park the truck for a short time, start up push the button, hear the grind and then nothing. No 4X4 light no sound no engagement of the rear tires. Its like one of the systems kicked the thing into neutral. Any help or ideas will be appreciated