I have a 96 disco,auto, 140k miles fanatically serviced by 2 prior owners ,never really taken off road.

Here is the problem: diff won't lock.

shifts fine,hi -lo lock/ un-lock( shifter is not stuck) all linkeage is there, but I get no light on dash no wheel hop etc.

No funny noise, no grinding, other wise drives fine.

What gives?

I want to get air lockers , but I need to fix this before I do.
I had some guy in a chevy blazer pull me out of the sand a couple of weeks ago.

That hurt

Please Help!