2008 Prius with new 12 V battery won't shift; lots of warning lights

You had me at beer.

 

Ah, Mazama -- a real Oregon brew


And, Homer, since he DID ORIGINATE in nearby Springfield OREGON

 

Off an article I'm reading from Lucious Garage:

"With Gen 2 Prius, the car will not allow the car to restart once the code sets. Toyota engineers decided HV faults were highly dangerous and the car was unsafe to drive. On the Gen 3 Prius, the trouble code is the same (P0AA6) but the car will still ready and drive. Thus we can interpret that Toyota admits this condition is not that unsafe after all.

Taxi drivers are tenacious as hell, and those commissioned to Gen 2 Prius often resort to disconnecting the 12v battery (or pulling the necessary fuses) to erase the P0AA6 and continue driving. I’ve seen them drive for months without repair (one went so far as to install a quick disconnect handle for the 12v in the trunk). Eventually the car developed another problem (more on this later) which necessitated a transmission replacement."

This sounds like it'll be okay to continue to drive it. Though if it happens again you'll need to clear the code before it can be driven again.

Something I found about Lexus, Toyotas luxury brand states that your P0AA6 code basically means your high voltage battery is grounding to the car chassis. In this particular article there was water found under neath the HV battery and it had to be drained, a new plug was put in, and a OEM Lexus "tarp" was installed. Yours may be a different situation but the site does have some easily understandable information and also shows what the INF (information) codes mean as there could be many reasons why you're throwing that particular code. I saw a previous user point out your battery was manufactured in 2016, perhaps when it was installed it was accidentally grounded to the cars body somewhere?

I'm by no means a mechanic, especially a hybrid mechanic but I'm kinda just thinking aloud.

As for her driving it, if it's fine under lots of load and stress then she might be fine for now. But from what I've read and understand this code will come back eventually and I would just make sure she's prepared and ready for the possibility of this happening again. Throw in some emergency snacks in case she has to wait for a tow truck or one of you two to get off work


Sources cited:
Art's Automotive

Gen 2 Prius (2004-2009) Transmission Failure, P0AA6, P0A92, P0A7A - Luscious Garage | Hybrid Specialists

(And a good one to read on)

Warning Lights, Triangle ! and VSC. Transmission Problems? | PriusChat

 

Currently the OP's car is not throwing any codes. I find it interesting that a supposed ground isolation fault has self-healed.

Couple of points in your summation. The P0AA6 does not mean that the battery case is grounded to the car chassis, as it is supposed to be grounded to the chassis. The car will throw other fault codes if it is not grounded properly and will likely not go READY. The key word is isolation. The HV DC on the battery side needs to be isolated from the rest of the 12 V systems. When you have the P0AA6 you have HV DC leaking to the chassis. Now, if the leak is in the HV battery, that might only be 14.4-16.8 V DC if it is a single module is leaking, but it could be so much more, so while it might be sometimes non-hazardous, I don't think it is something to be just lived with.

As for the OP just driving it, it will be perfectly fine as long as it continues to have no codes.

 

OP's car did throw codes but they were cleared at the dealership. The codes can come back again.

The high voltage battery pack isn't supposed to be grounded to the chassis, only the 12v battery pack.

"All hybrid and electric vehicles isolate the high voltage from the chassis ground. This is done to make the car safer. If the high voltage system was grounded through the chassis, contact with the car’s body and a high voltage component might result in a shock. The voltage used in hybrid and electric vehicles ranges from 144V to ~500V. Voltage above 60V DC or 36V AC can be very dangerous for we humans, so hybrids pack more than enough wallop to do us harm. High voltage insulation from chassis ground is one of the many safety measures incorporated to hybrid and electric vehicles"


iPhone ?

 

I thought my language was quite clear and said more or less that.

Again, you need to actually go back and read and understand what I wrote. The case of the HV battery is indeed bolted directly to the body of the car, so is grounded as it needs to be. Internally the HV DC is isolated from the case. It is when the DC isolation is compromised that there is a problem.

Your quote does nothing to make your case. It says exactly what I am saying.

 

Well yeah the case is bolted to the chassis but there's no electrical grounding. At least there's not supposed to be.


iPhone ?

 

If you have a ground and you bolt a metal container to it, the metal container is grounded. And, yes it is supposed to be, otherwise Toyota would have installed insulators between the case and the chassis.

 

The high voltage battery is in a metal case but doesn't mean the battery is grounded to the cars chassis. The HV battery is entirely isolated from the 12v battery which is grounded to the cars chassis. There is no electrical flow coming from the HV battery to the cars chassis. But there is an electrical flow coming from the 12v battery to the cars chassis.

 

This is exactly right, there is supposed to be no electrical flow coming from the HV battery to the cars chassis. So, when there is, there is a problem.

I think we will leave it there. If you are going to continue to argue against things I never said and refuse to comprehend what I am saying, we are going to get nowhere. Perhaps you just like to ague for the sake of arguing.

 

Your original post seemed to come at mine like I was stating her case was her cause which I did not state. I said somewhere along the system the electrical current was grounding. Perhaps someone should've read my first post before writing their own


iPhone ?

 

DTC P0AA6 means that the high voltage system has a ground fault. That is a BIG deal.

It will come back. I have experienced it with packs I rebuilt myself (nut split in half and contacted case) and Dorman remanufactured packs(I didn't open it, but it seemed like a POS pack). Your 12V system will experience those oscillations and it has high potential to screw up your electronic systems. There is very strong reasoning why Toyota won't allow the ready light to come on with this code.

You need to get your HV battery and system properly diagnosed.

 

Max Finch is exactly correct.

The high voltage leak if from cracked battery's is somewhat nebulous as the leaking electrolyte does not make a good connection so after clearing the code it may take a while for the system to detect another hi volt iso fault so you can keep driving till it detects hi volt leakage. I would imagine even a small voltage leak of >500 mV will trigger that code. Instantaneous detection of voltage also. Its a Hybrid safety issue so that voltage leak is highly monitored.

And Overworked is exactly correct too it is kinda a big deal mostly because we have seen a few battery fires with people clearing that code and continuing to drive. Not to beat a dead horse if it was me I would want to know whats going on with the battery. Is it the battery? Or is it the transmission that has a compromised winding? Or is it the Inverter? WE have seen a few torn up high voltage leads under the car also when it goes from the battery to the Inverter.. Its under a case of sorts underneath the car. Few people have chewed them up. has the OP ran anything over recently under the car?

It would be well worth a few bucks if I was the owner TO HIRE A BATTERY GUY to pull the battery out and take the cover off and look at the battery interconnect and are any battery's cracked and leaking. Take alot of pictures. Clear pictures. If the battery looks minty fresh and has matching cells with correct date code then you know its not the battery and is something else and can drive without fear. Except the car leaving you on the side of the road.It would be step one in my troubleshooting. I know its supposed to have a new battery. Show me.

Again I am in NO WAY INFERRING THE FEMALE OWNER SHOULD DO THIS HERSELF.
Hire her brothers battery guy. Its just the course of action I would take if this scenario was me. Or continue to drive waiting for the code to launch again and then scratch your head....but pay attention to burning smells.

 

Yes, wires, or cables. Leads (rhymes with seeds) is another term for them.

 

Didn't get to read all the details of this long thread, but from what I gathered, you have a bad transaxle. But the dealer did give you a brand new HV battery by a mistaken diagnosis, so that's a plus!!!

There was an extended warranty for older model prius from 2004-2007 with a bad transaxle P0AA6-512 & 613. If you have both those info codes, it would be the exact same problem. Maybe Toyota would be able to get you a warranty based on that info? The Technical service bulletin was issued in 2006 so it may have been extended to cover later models? Maybe or maybe not, you would have to ask Toyota. But this would only apply if you have both info codes 512 & 613 in your diagnostics. Below is a copy

http://www.justanswer.com/uploads/skyvisions/2008-05-31_080956_07_prius.pdf

If you cannot get Toyota to do a "goodwill" warranty on this repair, then just go buy a used transaxle for under $500 and have someone install it. I don't think it would cost more than $1000 labor to do it. Get back on the road with a brand new hv battery, compliments of Toyota's misdiagnosis. Think of the $1500 is what you spent to repair the HV battery, just like your brother. But your HV battery is good for another 10 years.

 

This is getting out of hand. It's time to slam a used transaxle in it and move on.

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