Transfer Case or Differential Problem

Question:When i put transfer case into gear light lights up and the rod is shifting the transfer case but tires not spinning only rears. How can i check its the transfer case not front diff. I have 2003 dodge ram 2500 3/4 ton np271d transfer case with hemi motorAnswer: Jack the truck up engage 4wd and see if the front drive shaft spins … if the drive shaft spins and the front wheels don’t it is the diff accuator or the diff. if the front shaft doesn’t spin then it’s the transfer case