99 4wd not engaging

i have a 99 chevy silverado ext cab 4wd....i belive something is wrong with the transfer case but dont know what....when i engage it into auto 4wd it works fine but when i put it into 4high or 4 low it stays into 2wd... you can hear the transfer case switching gears for both. but all that will spin is the rear wheels? as far as i know the front end is engaging cause when i put it in 4wd on the fly it pulls hard to the right. so i assume it is somehere in the transfer case it self.. if you could help me i woudl appreciate it.  (it is the electric push button style)

Welcome to the forum!!! Someone here should be able to answer your question, hang in there.

hi ,  i wouldnt asume anything yet ,   that button that engages the transfer case is prone to going bad ,   if you havent replaced it before you most likely will ,  have it checked out at the button ,  normaly when they do go bad they will default to 4 wheel drive only ,  but its electrical so anything could happen . 

Mine would not switch out of 2WD and it was a switch at the transfer case.  Not sure exactly what it was since it was warrantied but my bet is it is electrical not mechanical.

thanks i crawled under it... i had a buddy switch from 4h to 2h and you can hear a motor whine.. but i almost sounds like it is binding up... looks almost like a worm gear motor so imma try with that first and see what happens..