Error code p0aa6 please help!

That code is for a high voltage leak. The battery is a likely source. The leak could also be caused by the inverter, transmission, AC compressor, or damaged wiring. Every time you disconnected the 12 volt battery the codes were cleared and that allowed your car to start again.

 

I had the same problem with that code. Like strawbrad said it is a code that pops when there is a short between the high voltage system and the DC system. My mechanic told me that there was a known problem with the windings inside of the transmission eventually leaking the high voltage via short to the case of the transmission itself. He kept measuring the resistance through the connector of the transmisson and everything looked ok but he told me that he still suspected that the transmission was going bad. The main problem was that there were no sub codes which made the diagnoses difficult. He told me to keep driving the car and resetting the system until the sub codes were set. This took weeks to do and it was nerve wrecking. Finally the issue stepped up and made itself known and it was the transmisson. The problem was that when the transmission finally shorted out .... it took out the hybrid battery also. I spent $950.00 on the battery rebuild and $1100.00 on a good used transmission to resolve the problem. Now here I am 1 year later having battery problems again. At least you have a lot more miles on your 2008. My 2007 only has 157k. I swear...the Gen2's had all kinds of these problems. If I were you I'd get rid of that 2008 with all of the miles you already have on it or it is going to start costing you a shitload of money. What is crazy is that my neighbor has a 2007 just like mine with even more miles and he has not had one problem. I think that either you get a good one or one that is a borderline lemon.

 

It's *highly unlikely* the transmission was the problem. Yes it happens, but that's mostly a Gen-1 issue. Gen-2's and up, rarely. Like a handful of cases a year kind of rare.

Most likely your battery got hot and leaked, you are in L.A. that causes a HV Isolation fault. You needed to replace the battery and clear the codes. The rebuild did that and it worked. The transaxle was most likely fine when you replaced it.

A rebuilt/refurbished/re-whatevered battery is just a fancy way of saying "used". Your only option in today's world is a new battery. There are only 2 sources of new batteries with OE comparable specs. One is Toyota, the OEM.

 

We actually opened up the failed transmission right after the swap. The good used transmission was out of a 2009 gen2. Upon opening up the original trans I could see how the coils were completely fried. The guy doing the work is actually a childhood friend of my roommates. It is highly unlikely that he did anything dishonest. I have also seen many issues with the 2007 and there is a TSB that states that there was a problem with the 2007's withing a vin code range.

 

2,250,000 miles?

 

There should be a subcode of the code. Without that, all what you're doing is just trial and error. Have tech stream to check the subcode(s). That narrows the problem area down for you. Don't replaced parts yet.