Installing OEM Nav into 2014 Prius 2

It would be worth your $15 to sign up at techinfo.toyota.com. Sign in, go to the TIS tab, enter your model and year, then click the RM tab (repair manual) below. It will complain your "search" returned more than 500 things, but it doesn't matter, because no matter which one you click, the repair manual will open with its table-of-contents tree at the left. Then look for "Audio/Visual/Telematics", then "NAVIGATION / MULTI INFO DISPLAY", and within that you'll see two different choices for "NAVIGATION SYSTEM", namely "for Navigation Receiver Type" and "for Radio and Display type".

If you expand either one of those, the top thing you can open is "PARTS LOCATION" which will just show you some diagrams of the car with where the major nav-related parts are located. In each of those diagrams you can also see a drawing of the nav unit itself, enough to tell which type your uncle has been looking at. If the car didn't come with nav then some of the other things you'll see in the parts location diagram are probably also not there, like the navigation antenna assembly, so you can see the extras you'll need on your shopping list, and the places in the car where you'll be installing them.

Finally, in the same row of tabs with RM is also EWD (electrical wiring diagram) ... if you dive into this project, that's where you'll be to see what wiring harnesses and connectors are involved and how to hook it all up.

So it shouldn't be impossible, but the parts cost will probably be higher than the $400 for the unit itself, and you will be putting in some time on the project. This is the point where people often decide the maps on their phones work pretty well.

-Chap