Does any one have information on this and how it works it the transmission mine was unplug I plugged it in but still have no idea if it’s working or now any help would be appreciated 

Ugh, I'm dealing with this same issue myself, but I haven't finished diagnosing the problem due to other projects.

Start here, these threads have been helpful so far:

• https://www.ultimatesubaru.org/forum/topic/157979-4wd-diff-lock-not-engaging/
• https://www.ultimatesubaru.org/forum/topic/169810-getting-to-know-my-xt6-1st-suuub/

You can unbolt the 2 bolts that hold the cable to the passengers side of the transmission.  Then you can just push/pry the lever with any suitable tool forward and backward. 

That at least makes it useable for testing if needed. 

Gloyale (i think this is before he changed his user name) has some great info, probably in one of those links about how it works. 

It's probably vaccum related (clogged, leak) or the diaphrahm/cable is frozen/stuck. 

Or electrical - button, wiring,etc.  

See I don’t have the original instrument cluster so no light comes on at all I’ve been trying to find a original one but no luck some dumb rump roast before though the digital one would be cool without knowing how shitty and unreliable they are 

There’s two different gearboxes that use the same vacuum actuation system - the single range part time 4wd gearbox and the All Wheel Drive (full time 4wd) gearbox in both single and dual range configurations. PT4wd, the engagement lever on the side of the gearbox pivots from a high point with the lever pointing down  the FT4wd/AWD locking lever pivots from a low point on the side of the gearbox and the lever points upwards.

Do whichever of the following first, it doesn’t really matter.

You will need to find out if you have power at the solenoids and that it switches with changing the switch for the diff lock/4wd engagement.

If that checks out you need to look at vacuum, both the source of the vacuum and the hoses to the diaphragm - and ensure the diaphragm itself doesn’t have a leak. 

The locking/engaging mechanism isn’t known for issues. You can manually check the engagement by raising a wheel off the ground and doing as idosubaru said with the removal of the cable off the side of the gearbox while rotating the tailshaft to get the engagement/locking mechanism to line up to do its thing. 

I hope that makes sense! 

Cheers 

Bennie