4x4 help

i have a 85 4x4 front in would not lock in but i found a vacum bad fixed it i think.but the indicator inside cab by the shifter doesnt light up at all in 4 wheel or 2 wheel drive check my fuse anyone know what would cause that?

Your in luck.

I found a site with a really good diagnosis page on the subject.

Here's a link http://www.4x4posi-lok.com/PDFs/TSG_chevyK.pdf