Just bought a used 2015 Cherokee Limited 3.6L FWD w/ 120k miles (I know, what was I thinking) about a month ago. I'm running into an issue with the power steering where it will shut off mid drive with no rhyme or reason. I've been looking on different site as to the cause and how to fix, but no specifics. I know to test the battery and altinator since its a hybrid steering sytem, but I can not seem to find where the power steering resivour is. I need help in diagnosing this issue so I can promply fix it.

P.S. I ran over a screw and had to put the spare tire on that doesn't have a pressure guage in it about 2 weeks ago. during that time the tire warning light was always on, my initial though was that because these cars just have to have a brain now a days, that the tire sensor was linked to the issue of the power steering in some way. Replaced the tire today and the system still says that it doesnt have air, so I also have to figure out how to reset that. Any help would be greatly appreciated. Thank you.