P0AA6 explanation

I don't know if that's the case or exactly what's happened or if the insulation is just broken down in the compressor from age 240,000 mi I think The car was owned by people that were in the trades so it's very possible it had its air conditioning service at one time at some place that wasn't up on electric compressors and the dielectric fluid needed or whatever the problem is with the oil. And that may have been done incorrectly which sped up the destruction of the compressor but still at $240,000 that's not horrible

 

I'd think you could get it all fixed up for less than that, with some shopping around.

 

I meant not bad for 240,000 mi. This is something we need to change the compressor for correct because the windings are something internally is damaged from running oil that is I guess conducting electricity and wreaking havoc on the system I can't just flush it all out clean it put the right oil in it and gas it back up because the damage is done correct?

 

It coded again today when my other half got in the car ready to come home from work she had to clear the codes twice with our Inova scanner and then the car of course like everybody else's boots right up no lights on the dash at all and drives perfectly all the way to the store and back to the hacienda here I'm sure it was the P0AA6 code with the same subcodes that we're dealing with here funny thing is is I've got the air conditioning unplugged so I guess I'm back to the HV battery computer it looks like there is no wiring issues anywhere everything on this car is whistle clean wire and connection wise everything looks essentially like brand new garage all these years whatever.

 

If it is still telling you P0AA6-611, then you'd be doing yourself no favors to ignore what it's telling you and go back to looking at the other end of the car.

If it's saying 611 and the compressor's unplugged, start looking at the rest of the stuff in the 611 area: the wiring to the compressor, and its connections within the inverter.

 

Now it's 612 sub I've got battery open and see nothing but clean . Showing 56 point some odd volts at the orange plug bolt with the other lead grounded holding steady what voltage am I looking for at this stage with the orange plug plugged in the relay closest to the front of the car shows 94 volts DC and the relay behind it is showing like 124 volts everything looks very clean I'll have to pull the battery outside ways and get a flashlight and look underneath to see if I see any leakage I push the very lightly damp piece of bounty across the bottom of the case with a piece of wire and drug it back out It doesn't smell or taste like there's any battery acid on the piece of bounty I hate to break the whole battery all the way down for pretty much no reason this battery looks like it was just while I know it was just built and assembled it has lines on all the cells blue and black marks I called the kid who built the battery and he said everything seems normal as far as you can tell. I'm just not sure what kind of volts I'm supposed to see on the orange plug the bolt when you're doing the test from that bolt to the case or ground.?

 

Yeah it's interesting how the code is migrated from 611 to 6:12 so from the air conditioning inverter circuit up front now to the battery in the back. The battery in the back is clean as a whistle I mean it's ridiculous I've never seen a battery so clean inside course most of them I've taken a part of Been at $250,000 mi

 

Tom, you crack me up!!

 

A Prius NiMH battery doesn't have any acid. The electrolyte is a solution of potassium hydroxide (or a mixture of potassium and sodium hydroxides), both strong bases.

 

The leaking battery in the '04 is a factory battery there's a bunch of white krusty crap on the bottom of the tray in between some of the modules that same krusty krab is there If I wet my finger touch the krusty crap stick it to my tongue it tastes like battery acid although yes you're right it's not liquid I have read about some people trying to re-wet these things and all this kind of nonsense not having any of it.

 

It tastes like battery alkali.

For most people, acids will taste sour, bases will taste bitter. When was the last time you licked some H₂SO₄ to compare the flavor to this KOH?

It's ok, I'm really not advocating licking either stuff.

 

A long time I guess but that's my go-to methodology must have worked pretty well looks like I'll make it to almost 80 so I'm not going to worry with it now. Whatever it is it dries and turns white and it came out of the battery and it helps it make its electricity does whatever it does chemically and it's leaking so we're throwing that mess out and putting in something that doesn't do any of that sort of nonsense then we're driving without lights and crazy crap going on just because it's old and leaking and wore out.

 

Is there any new update on your P0AA6 code ?

 

Yes the guy that built the battery for me came back with another one changed it it past the test with the voltmeter and the battery is isolated The one he removed that he built 6 weeks prior was no longer isolated He said he could feel it when he picked it up. I don't know exactly where the isolation took place there was no leakage onto the painted beautiful battery tray so I'm guessing one of the screws broke the plastic on one of the modules and was grounding to the frame that way I'll have to ask him next time I talk to him but by then he'll have been through 20 more batteries or so so I'm sure it's hard to remember one from another but those bottom screws are a common spot for these things to fail seems to me the rack squeezed together and then the slots on the ends of the rack itself bolt down to the case there's really no need to have those screws in the individual modules even in an accident long as they're covered by that top cover they're still bolted to the tray but just the tubular frame and plastic ends are bolted The modules and factor squeezed and not individually bolted to the tray bottom.

 

When I have had an Isolation fault (P0AA6) I check the battery case to the orange plug. Be carefull because I have seen 90V DC and that will knock you back. The 2 termanals in the plug represent one end of the battery or the other. For small leak you may need the megohmmeter. You will need to taake the cover off and test the two ends of the battery to determin which end is giving ou the fault. Usually there is no fault on one end. once you determin which end then you need to test each cel. To do this you will need to remove the bus bars on the easy side, then check for voltage from each module termanal to the case. This is where you need the megohmmeter since 7.2 volts does not push thru a leak and show up on your meter. I hd one case where all but 5 of the cells had shorts. I think it is because of torqueing the bottom bolt too tight and cracking the plastic around it causing a fluid leak.
Replacing that cel is the repair. On the 1st gen I even put duct tape on the case where the bolts go and didn't reinstall the bolts, because they were so prone to leaking and the terminal glue would also conduct electric.

 

Another point is the leaking rain in the seam where the rubber seal is in the roof. If the fault is intermitant or more when it rains it may be the seal on the roof. Yu need to lift the rubber seal wher it meeets the hatch back. There you will see that the factory sealing gun could not seal a small spot by the clip for the rubber. There is 1.5 inches before the clip and 2 inches after the clip that are not sealed. This leaks right above the battery and it is not good to have water and 300 volts dc mixing. Even if this is not an issue it should be sealed with silicon or gorila glue after cleaning the area. All 2nd gen Prius have this problem causing rust in the trunk and conector problems for the cooling fan on the right side. The connector corrodes causing a fan fault code.

 

Thanks everyone for contributing to this post.
I'm working through a P0AA6 right now.
Here's what I found working on this today.

1. White crusty stuff under several modules
2. Bluish remnants on metal brace (and vent) on passenger side of vehicle
3. Blue leakage from side of one module

I attached pictures.
If I clean this up is it a good bet that will solve the P0AA6 problem?

The code first appeared after the first rain of the season, the code happened the next time I started the car. Not sure if that is coincidence or a contributing factor could be the Gen 2 issue with the hatchback sealing as was mentioned in this post previously.

Another fix I heard discussed here was blocking the contact between the bottom of the modules and the case potentially with electrical tape. I agree that the bottom of the case bolts that drive into the modules tend to become problematic, especially after multiple DIY module swaps and the pack not always going precisely back together the same way.

This is my 9th or 10th time removing the pack and replacing modules, so at this point, I'm feeling like retiring the bottom bolts. I believe they are doing more harm than good, unless there's any strong reason to keep them? TYIA

 

I've also added readouts from Hybrid Assistant.
10 minute test while parked with AC on to potentially draw out underperforming modules.
Looks like block 3 and block 12 are ready to be swapped out in my assessment.

Appreciate your suggestions and feedback!

 

What are the INF codes (sub-codes) that you have with the P0AA6 code?

 

Hi Brian, thank you for jumping in. I wasn't able to get sub-codes. Tried multiple apps.. I have a Carista and Hyperlink readers but couldn't get sub-code information. What do you recommend in terms of how to get sub-codes?

Because I struck out trying with all the apps and OBD2s I opted for trying to diagnose the problem visually and went ahead and removed the HV pack and am working on it currently.