I have a 2001 AU Falcon ute, unmodified.
It has been parked for 18 months. We had a leak in the cooler, lost a lot of oil, we put some oil back in, but had no idea how to to that properly.
It would not shift out of 2nd gear, so we parked it. 1st 2nd and reverse all work, we thought it was a low oil problem.

I was able to fill the transmission properly today. Added just under 2 liters of oil.
Nothing changed.
I am i a small desert town in North Qld. Mechanics only know Caterpillar, or Landcruiser.... cant even pronounce ford!

I had a 91 Cheve that had a problem with the o2 sensor, and would not shift out of 2nd, does this transmission have similar limp mode?

Where do I look?
What can I do now?

Thank you for your help.