The side doors on my g20 van are the 1/3 and 2/3 type. The 1/3 door can be opened and it stay open. The 2/3 door opens and closes on itself.

Why?

Probably locating mechanism is not working properly anymore. Hope some knowledgeable would chime in.

This is the door latch that keeps it from opening all the way. I would say the curl on the end just before the tab Im pointing at has broke...

^^^This

Either it's broken (the door opens all the way up and doesn't stop at 90*), or it's gap is too wide and is not holding the door anymore (opens and stops at 90*, but won't stay open.

I had to get a new one a few years ago for my van, but it was harder than I expected to get a good used one, and a NOS one was almost $70.

BTW
They're called 40/60 doors. (40%/60%)

It does not look broken. It will stop the door from opening all the way, but it does not stop it from closing by itself.

OK there is a spring on the other end, it keeps that latch up so it hooks the loop around the post, keeping the door from closing. Your spring is wore or gone.

Here in West Texas you gotta be aware of the wind.
Pretty damn dangerous. The detents in the doors on the Mexican Dodge, are useless.

The little 40 door is the only one that will stay open on the latch. I use a walking stick or my cane on the doors.

Hafta be quick though! I've had the wind slam a door, and snap 'em clean in half.

Yeah, it's a drag having to replace a stick. But. Always glad when it's not my leg.

You broke the cane again ?

Need another made ?