Prius cut out mid drive, no ready light, car will not start at all, no error codes.

It'd be interesting to know what your HV battery voltage is sitting at rest not working anything not starting the car MG1 I think just locks up and becomes your starter when the car needs to start since we don't have a starter mounted to the block of the engine and a 12 volt wire going to it to spin the engine around to start it the motor generator does that because in this type of vehicle the reciprocating mass of the engine when in drive going forward is always turning there's no neutral per se not like you would have on a normal car so every time the engine wants to start it's done with the shaft of that motor generator would have you the gearing off of it etc and then the battery ECU monitors the battery voltage for the HV battery and if there's not enough of that it can't lock up MG1 or allow it to spin to start the engine so you would be needing to check the HV battery make sure it's isolated from the rest of the car that is a code HV battery isolation fault which you say you don't have I don't know if you have a capable scanner that would show you that code if you were plugged into the car because I don't know the scanner you have there's a big hullabaloo over scanners that will work with most Prius If you don't have one you may not see everything that is a thing.

 

With key just in the “On” position, can you not pull codes?