P0AA6_526_613_intermittent

Hey guys,

I know this has been brought up multiple times in other threads but just wanted some opinions on my findings from the guys that have been diagnosing these vehicle for years. I just purchased an 07 Prius with 160k about a month ago and got the red triangle light a few days ago. Just for background, I have a fair amount of automotive knowledge and work on hybrids and electrics for a different brand, who will not be named .

I got a techstream and pulled the DTCs and got P0AA6 with info codes 526 and 613. I know this points at the Transaxle, AC or the component side of the inverter assembly. I monitored the short wave voltage while driving the vehicle and while stopped but pulsing the ICE engine on and off and was not able to duplicate the DTCs again. However when I am not in a boost condition (high and low voltages roughly matching) I do see the short wave voltage being to drop intermittently. Sometimes it will drop to around 4.5v and sit there for a while (5 minutes +) or drop down to around 3.5 to 4.0 and sit there for roughly 5 minutes or so. Then sometimes I will see it drop to 1.5v for maybe 15-30 seconds and then go back up to 4.99v, this usually only happen if stopped and i have turned the ICE engine on and then it turns back off immediately. I have a fluke isolation meter and have check the isolation resistance of all the components and they are all testing good currently (550M ohm at 527Vdc).

Some other things that I have noticed while inspecting for this concern and during previous drives prior to the DTC is that I pulled off the inverter cover pretty quickly after turning off the vehicle and pulling the safety plug when the short valve voltage was a little low (4.0-4.5V) and got a decent wiff of hot/burned electrical. Obvious there's a lot of electric conversion and energy going on in there so this might be normal. I have also noticed that since purchasing that when the engine turns on, and especially off, while driving that it seems to be more violent then it should be. Again, this is my first Prius so I'm basing this off of other hybrids and just general automotive experience, but sometime when the engine turns on/off when the vehicle is parked the whole car will rock back and for and it will sound like it was stumbling while turning off.

I think this is unrelated but there is also a rolling misfire at idle that is present on all cylinders. I have replaced the spark plugs and coils, all fluids and filters when I bough it and it has remained unchanged. Thinking maybe fuel injectors but I haven't really dived into that one yet since the red Triangle light came on. Also the battery was "rebuilt" about 3 months ago for the previous owner by a local shop. Not 100% on what rebuilt means in this case but figured I'd mention it even though the info code point at the front of the vehicle.

Last thing of note is that I got this for my significant other since she just got a new job that require more driving and the light came on at the end of her drive home as she pulled into her parking spot. The drive is roughly 45 miles and 1 hour.

Based on my limited Prius knowledge I am leaning towards a Transaxle since they seem more common to fail than inverters, happened after prolonged driving (maybe a heat issue) and I have seen lots of forums and article describing basically my exact symptoms and having it be a fault Transaxle but I just wanted to reach out to you guys here and see if there is anything else you would recommend checking or if just one of those start with A and if it doesn't fix it then do B things.

 

Thank You!

I haven’t performed that test exactly and since I can’t get the DTC to set again I’m not sure it would work. However, I was watching the shortwave voltage and putting the vehicle in different scenarios to achieve essential the same thing. At one point it was at 3.5v fairly steady with the vehicle stopped, in park and no RPM on MG1. That is why I am a little suspicious of it being an inverter.