P0A4B Code, Transaxle/Generator

While driving from LA to Iowa city, my prius 2005 broke down right before driving up the rocky mountains. Luckily it broke down at a gas station, but it was still a very traumatic experience as my sister and I was stranded in Colorado and had to pay up to $2,000 fees in hotel, car rental, flight and for my car to be transported to Iowa city. We both had to rush for employment reasons.

It only has $87,000 miles on it and I've used the dealership for all my maintenance services for 9 years without fail, on time each time. No negligence on my part.

The dealership diagnosed the problem and reported that the R axle got bounded and had damaged the sleeve of the transmission, a repair costing ($2,000-3,000 for a USED transmission). When speaking to other friends, they said that is a rare problem and that I could have had a defected car that could have costed my sister and my life.

However, when I attempted to make calls to Toyota Corporation (2x/day), they were ignoring me. Karma the representative for my case, said she would get back to me in 2 business days (thurs) after the diagnosis was complete, however I did not hear back until Monday. I was never able to reach her or a supervisor until monday. Because of the delay, I've spent extra $30-40 per day on my car rental (this I communicated to Toyota). When she finally did call (once I became angry), I found out she did not even call the dealership for the actual diagnosis. I spoke to the supervisor Steve who also unapologetic and re-reiterated the fact they could only give me a discount of $1,000 if I buy a new toyota.

You can imagine my shock that after telling them I spent $2,000 to salvage my car, they offer an incentive for me to buy a new one, an option that I'm sure is profitable for them.

Later I did some research that stated that my transmission COULD be a part of the hybrid synergy system, which has a warranty for 2005 prius under 100,000 miles. I'm not 100% sure.

Because toyota corporation have been avoiding my calls, I am considering complaining to BBB.

 

Well, I have read all the above regarding P0A4B which is the OBD error I received. My 2008 has 285,000 miles so quite a few. I understand it could be that the transaxle/generator needs to be replaced or if I am lucky there is a wiring issue. I first got the error 2 weeks ago and barely made it the 8 miles I had to drive to get home. I then read the error and cleared it. After clearing it I started the engine and the red triangle and all the other error lights were gone. I ran great for the next 10 days, during which I did the Signal Check where I discovered the 12 volt battery had low voltage. And it was 4+ years old so I got a new one from a Toyota dealership for $200. (I realize a low voltage 12 volt battery can, on occasion, cause weird errors to be thrown. Well, a day or two after replacing the 12 volt battery I got the red triangle again and the same P0A4B error was present, and clearing the error does not help as I will get the red triangle right back again and with the same error. The reason I am posting this is because I explained this all to the owner of a local hybrid shop and he tells me he has worked on over a thousand Priuses and says the 2nd gen Priuses are nearly bullet proof and he has only replace the transaxle/generator 2 or 3 times. He thinks it is either a wiring issue or the inverter has gone bad. But it seems to me if the inverter went bad it wouldn't throw the P0A4B error, would it? And that is my question for this group. - My concern with the owner of the shop is I think I would get a different error if it was the inverter that has gone bad and he charges $260 just for the diagnostics and that he doesn't apply that $260 towards the labor if he does replace something. Any thoughts? (I am worried about paying him $260 only to have him do his diagnostics and then tell me that it is the transaxle/generator after all.)

 

There are three possibilities with respect to P0A4B. A wiring problem, the transaxle failed, or the hybrid vehicle ECU failed. The Toyota repair manual explains how to verify the wiring. Resistance checks are used to determine if the transaxle generator has a problem. If the first two areas are OK then it is recommended to replace the HV ECU.

 

That was very helpful information, Patrick.
I'm going to bring it into a shop and ask them to verify the wiring and do the resistant checks you refer to to determine if the transaxle / generator has the issue. And I'm going to hope it's just the HV ECU that needs to be replaced or they can easily resolve the wiring issue if that's what it is. In other words, I hope I don't have to replace the transaxle / generator! :>)