2012 Prius V brain

There are a number of different computers in there. My understanding is that if you pull them all out they will fill a bushel basket. The ones I know are all single purpose, but they play well with others. I'm not sure which if any would count as the "brain". Do you have the error codes?

 

yes, the related ecu can be replaced, or it might just be corrosion at the connector pins

 

^ This. The trouble codes give you the best start on figuring out what is going on with the car.

Some people think a particular trouble code is all about some particular part, so they go look at that part, and if it looks ok, they jump right to "the brain malfunctioned".

But that's never what a trouble code means. A trouble code only tells you about some unexpected condition one of the "brains" happened to notice. The "brain" (ECU) is not able to crawl out of its box and go look for what part is at fault or what caused that unexpected condition, so a human has to do that part.

A trouble code can be looked up in the repair manual:

Toyota Service Information and Where To Find It | PriusChat

There will be a box called "DTC Detection Condition" that explains exactly what the ECU had to see to set that code. Following that, there will be troubleshooting instructions to help the human figure out what's at the bottom of why the ECU saw that.

Do the ECUs/"brains" ever malfunction? Well, it's not impossible, but they are solid state electronics with no moving parts, so it's very rare. The vast majority of "I think it's the brain malfunctioning" stories end up that the trouble code(s) meant exactly what the repair manual said.

 

How much do they cost, or how much to have installed?

 

You need to describe what problems the car is having. Have you used a scan tool to retrieve the trouble codes?

There are 12 to 14 different ECU's in your Prius. Are you just going to guess which one to replace? ECU's rarely go bad. You need to diagnose what the problem is with the car.

 

If I remember right, it's closer to a couple dozen in a gen 3. A dozen or so in a gen 2.