need help with 95 LT 4x4

i have a 95 blazer. i push the 4 wheel drive button and it light up fine. im trying to go up a hill and only the back 2 tires are spinning but the frount tires are not moving at all. i put the truck in 4 low and i def here it click in but still no movement in the frount.

im wondering what could be the problem. i get no ses light and my 4x4 lights stay lit when i push that specific button, no flashing what so ever.

i also reciently had the tranny changed and i had the shop look everything over. suv performs fine and drives great.

let me get all of your input!
thanks

Transfer case encoder motor is shot.

is this hard to replace.
if anything i will try and do it myself.
also are there any post on how to do it and where i can get the part from?

thanks for your time blazer lt

same thing happened to me. i would push the 4wd button and it would go in and i would even hear the clicking from the transfer case. but i would go to a hill and i would just spin the back tires. it ended up being the vaccumn actuator under the battery tray. take a look at that and see if you have a tear in the black rubber boot. if you do it needs to be replaced. it is $88 at the dealer, i found one on gmpartsdirect.com for 48.92. part #25031740.

Yes, check that also.

thanks for the time guys, ill check in the am and get back to ya