AX5 just lost reverse

[Stoopid Jeep]

No weird sounds, no warning.
I backed into the driveway last night with no issues. Today I drove to the store and there is no reverse. It doesn't even feel like it tries to go in, no grinding, no nothing. It doesn't even feel like the slot where reverse was is still there.
It's like it's locked out.
Every other gear works fine, I was in 5th on the freeway just before I discovered my new reverse-delete upgrade.

Any ideas?

 

[JKP]

Will it go into R with the engine off?

 

[Stoopid Jeep]

Will it go into R with the engine off?

Nope. Not even if I let it roll back.
It's like reverse no longer exists.
There's not even so much as a little divot where reverse used to be.

 

[Stoopid Jeep]

Update:
the 5th/R shift fork has what is called a "shift interlock" its a steel ball that moves between detents in the 5th and reverse shift rails. it locks one shift rail in neutral when the other is shifted into gear, ...anyway

the passageway that the ball rides in, is drilled (machined) into the shift fork. there was gauling inside the passageway that trapped the detent ball locking out reverse.

the weird thing is, there was no rust or foreign material found in the gear box. there was no other signs of damage. the ball was still smooth and round, the oil was clean and full...

I have had 3 veteran transmission guys look at that shift fork and the only theory anybody has is; electrolysis caused from the backup lights and a bad ground.

we replaced the shift fork, the detent and all the seals. I think I'll add a big fat ground strap th the gear box too (it couldn't hurt)
I didn't post any pics because the camera doesn't really show the damage, I would almost need a borescope.

Steve at Sun Gear Transmissions, in Post Falls, ID, charged me 400 bucks (parts and labor) to go through the trans, seems like a good deal. Thanks Steve!

The jeep is back up and running, it's almost time to think about putting a top on it ...almost