4 Whell Drive Issues????

I went up to the mountain yesterday and found out my 4 wheel drive doesn't work. I put it in 4 high and the light comes on i start to spin the tires and the 4wd light will flicker and blink. Do you know what would cuase this..... thanks.

Some old posts..."search this forum"...

http://www.automotiveforums.com/vbulletin/showthread.php?t=739949&highlight=four+wheel+vacuum

Thanks. I jacked up the back end and saw that when you put it in 4 wheel the driveshaft starts to spin in the front but the wheels don't turn.... any ideas

Yep..the vacuum system...