4x4 not engaging

my 94 sr5 4x4 (v-6) will not shift into four wheel drive. other than checking for the obvious (fuse) what else could be wrong. the shift lever moves alright but no 4x4 lite on dash and 4x4 does not engage.

You might need to adjust the linkage underneath the truck. Automatic or 5 speed?? Manual or electric transfer??

Automatic tranny wity electric transfer.