Yes interlock. That's it. Shifting into low cannot be done. Definitely placing gear shifter into neutral with engine running. Tried when running 5mph or slower as well. Is it a cable possibly?

 

There is a cable connected to the 4wd shift ****. Do be careful.. The cable in mine snapped in the last snow storm. They commonly seize as soccer mom's don't usually need low range.

I suggest you gingerly try and push the lever forward. If it isn't gonna go, lay off it and look deeper. I had to remove the center console and drill out the rivets that hold the shift plate in to find out what broke. Only did it this way because i was sitting in about a foot of snow.

 

Looks like a $300 job for my Indie ZERO! : )

 

It isnt that bad. Took me 30 minutes to get that floor out. Then again I happened to have an 18v drill with the correct size bits in the cargo bay. And I was plenty angry. Adrenaline is good.. sometimes. Lol. See.. I broke the little electrical plug for the park lock solenoid... now I have to disengage it manually.