4wd won't engage

i have a 1990 jeep cherokee inline 6 with part time four wheel drive the problem is the front axle won't engage i checked the axle motor it moves freely with a little vaccum i'm getting vaccum to the switch on the transfer case but it's not comeing back thru to the axle so my question is should i buy a new vaccum switch and replace all the hose's any input would be good the ground is strarting to un thaw and i wanna go play :) have a great day and thanks in advance for the replies. oh the part time light use to come on when i pulled up the 4 wheel drive lever but nothing comes on now.

i have a 1990 jeep cherokee inline 6 with part time four wheel drive the problem is the front axle won't engage i checked the axle motor it moves freely with a little vaccum i'm getting vaccum to the switch on the transfer case but it's not comeing back thru to the axle so my question is should i buy a new vaccum switch and replace all the hose's any input would be good the ground is strarting to un thaw and i wanna go play :) have a great day and thanks in advance for the replies. oh the part time light use to come on when i pulled up the 4 wheel drive lever but nothing comes on now.

Sounds like youve narrowed it down pretty good. Its either the vacuum switch itself or the vacuum line running from the switch to the motor. Can you pull the vacuum lines off the switch and feel for vacuum with it in 4WD?
I havent been under mine to look at the switch in awhile but if I remember right, the switch has a block of four hoses going to it. Two of them will go straight to the front axle motor. If you pull that block off, can you feel vacuum at the switch where those lines connect?