Have to unplug battery cables and hook them back up every time I start the car

Yes my guess right off the top would be you have the battery isolation fault It is the code with subcodes I should know it by heart but I don't this this disconnection of the battery is common to clear the code because I guess you don't have a code scanner.? If you have a code scanner even if it's an old one if you plug it up and clear the codes twice in a row even though there's none showing or what have you you'll see the check engine light and the lights go off in the car will start and then when you turn it off again it will not restart till you clear the codes or undo the battery terminal. Generally a mediocre code scanner might pick up that fault today and give you the code it'll give you the code and may not describe it properly on an older scanner. If you're keeping the car and you're really going to run this thing and all of that you should really look into it a u t e l a p200 it'll save you a lot of nonsense very quickly very quickly you'll be happy you have it It may even save you a few bucks for unscrupulous mechanics.

 

Are there any warning lights or messages showing on the dash?

If there are, have you read the trouble codes that go with them?

 

Ah, didn't spot that info in the OP.

 

Yes your CM monitor display is acting up so it comes and goes usually when you want to when you can open the trunk you can move the little plate on the right side of the tail light carpet right underneath the tail light undo the ground there easily with a 10 mm and a short extension and move the ground wire with the hatch up until you see the door open icon light up then lock the ground down go and open the front door close the hatch note that the door open light is still on and now you will have a display now boot the car up see all the red orange lights scan the car and I guess report back the codes and you'll be golden and that's pretty much that You can get another display with your mileage and everything all done up for you with a rebate and the total cost will be like 170 bucks you'll screw it into the desktop It's pretty easy it'll avoid that for the rest of the car's life if that matters to you I don't do enough traveling so I just keep the car full and don't care if it's going to a daughter or a wife or a significant other the dash gets fixed so we don't get causes running out of fuel on the side of the road but other than that really makes no difference

 

If you're five or eighty-two / This is something you can do

 

This ain't no fix it's just to get your lights lit up so you can do what you need to do and make a determination of how you're going to proceed It's no fun having to do this every couple of days and if that's how it's going to be for a while if you're parking on your private property at night just slide a piece of cardboard where the trunk latch is set the trunk down it looks closed the red door open light is on on the dash hard to see for criminals unless they're really looking they shouldn't be at your private residence and when you come out in the morning just move the cardboard close to trunk start the car in your car stays awake essentially is what's happening here won't kill your battery unless it's dead already anyway this just buys you some time to call Texas hybrids and get the part ordered and do what you need to do

 

OMG!!
I'm having same problem what did you end up finding was wrong with prius?????? It's driving me crazy.

 

That sounds like the hybrid isolation fault You should get a capable code scanner and see if that's in fact what you have I can't remember the code but if you Google it it'll tell you .poa6 or such

 

Are there any warning lights or messages showing on the dash?

 

No warning lights ..that's what blows my mind...crazy thing I can drive it about a couple days...wake up next morning and won't start...pull the white plugs from positive connection resets and starts

 

That clears a fault . Now try n clear codes back to back with cheapo scanner or any scanner . Same result. Do this before unplugging 12V.

 

What is the voltage of the 12v battery when the car does not start? How old is your 12v battery?