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Genchi Genbutsu
Genchi Genbutsu, Toyota Master Technician
Category: Toyota
Satisfied Customers: 4395
Experience:  Toyota Certified Master Diagnostic Technician, ASE Master Technician with L1 Advanced Engine
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We have a 2010 Prius that is completely dead in the water.

Customer Question

We have a 2010 Prius that is completely dead in the water. Display reads "P Brake Malfunction. Make sure you are parked in a level spot and press the power button"... we are on a basketball court. The car won't do anything. The engine won't run, we can't get it into neutral... We bought a new battery and installed it.
Nothing is working.
Submitted: 1 year ago.
Category: Toyota
Expert:  Ted Ritter replied 1 year ago.

Hello, thanks for posting

If there were no warning lights on prior to this event and the car was running normally the most likely cause is that the 12 volt auxiliary battery in the trunk is discharged or just needs to be replaced, these are small batteries that resemble regular car batteries, if it is original and was never replaced before it most likely needs to be replaced at this time, once discharged to the point where it won't accept charging from the hybrid system it usually needs to be replaced.

Customer: replied 1 year ago.
We replaced the battery and are still having the issue.
Expert:  Ted Ritter replied 1 year ago.

Thanks for the reply

The next step would be to get some diagnostic information from the computers.

Customer: replied 1 year ago.
Checked the codes and it's only showing a U0293 code.
Expert:  Ted Ritter replied 1 year ago.

"Lost communication with HV ECU' causes:

 Wire harness

There are also more "info" codes which are secondary codes and help with diagnosing,

sorry, don't have a specific answer here, you'll have to have further diagnosis done by a certified hybrid tech that can access your vehicle, only so much I can do here, not about to guess what it may be.

Expert:  Genchi Genbutsu replied 1 year ago.

New Expert here. This is a circuit code for the CAN communication system as shown here. Have you tried clearing the code and restarting the vehicle?

Was this vehicle ever in an accident?

Customer: replied 1 year ago.
It's never been in an accident, that we know of. We bought it used with 68,000 miles.
Expert:  Genchi Genbutsu replied 1 year ago.

Do you have a TechStream (Toyota Factory) Scan-tool?

How many miles are on it now?

Customer: replied 1 year ago.
We do not have that scan tool. It has 130,500 miles now.
Customer: replied 1 year ago.
I just have a basic BDII code scanner. Tried clearing the code and it didn't help.
Expert:  Genchi Genbutsu replied 1 year ago.

Are you a repair shop or the Owner of this Prius? Have you ever performed this type Hybrid repair before?

Customer: replied 1 year ago.
No, just work on my own vehicles from time to time. I was looking for help to get it started so that I could take it to the local dealership.
Expert:  Genchi Genbutsu replied 1 year ago.

I see. Unfortunately this is a very complex problem involving the CAN Communication system. There is a Hi CAN and a Lo Can side to this communication line with one side "going up" and the other side "going low". They are redundant mirrors.

Here is a nice video showing you how the CAN system works and what it would take to try and get this Prius started.

The only thing I can think of to try is to wiggle some wires at the HV ECU located with the High Voltage Battery (located behind the rear seat) and see if communication can be restored to get it started. Be warning that this is High Voltage that can seriously harm/kill you and that it may not even work.

I apologize in advance for this Prius issue but some things are beyond our control.

Customer: replied 1 year ago.
It turned out to be a relay per the Toyota dealership. Thanks for your help.
Expert:  Genchi Genbutsu replied 1 year ago.

That is awesome! I am glad that this got fixed with hopefully little cost $. Please know that I strive to give Excellent Service.