Gen 2 05 P0AA6

The P0AA6 HV Isolation fault has nothing to do with individual module voltages, and it's exact location in the battery cannot be determined using them. Most of these instances are caused by electrolyte seepage from the module making contact with the metal battery case. Corrosion only on the busbars will not cause a P0AA6.
I've seen seepage from 3 common locations on a module:

1. from one of the module terminals. You'll see blueish residue on the module case below the terminal. (could be dry or wet)
2. sometimes it is due to a small crack on the bottom of the module
3. there is a steel insert pressed into the bottom of the module for the mounting screw. Sometimes an internal crack in the housing will allow electrolyte to make contact with this steel insert, which in turn, is contacting the metal case.
4. very often, you can see a brownish stain on the metal case at the bottom of the modules where seepage has corroded the metal. I had one battery that actually had a drip on the bottom from a crack.

Other than the P0AA6, your battery looks to be in pretty good condition. You can disassemble and clean the modules to remove the seepage residue. Then take a voltage reading between the metal insert on the bottom of each module and each of its terminals to see if there is a steady DC voltage reading. There will often be a small reading that quickly dissipates to near zero. Any module with a steady voltage reading during this test should be replaced. I've even experimented with modules that have this problem and was able to eliminate the P0AA6 by cutting 2 pieces of 3M electrical tape to match the width of the module and placing them over the metal insert. Reassembled the battery but did not use a mounting screw on that one module. The "grounded" module was effectively isolated from the metal case. That experiment is still ongoing, as the battery is still in service in one of my Gen 2s.

Prior to disassembly, you can make an overall check by removing the safety disconnect (in case you haven't already done that, safety first) and connecting one meter lead to the metal case and then touching the other lead to each main relay (on the battery side under the white plastic covers). On a good battery, these reading should be effectively 0 volts. If one or more of the modules is "grounded", you'll see a steady voltage reading. Typically in the double digits.

Can you post photos of each side of the modules so we can see the entire case surface?

 

So this is an original battery on this 05 generation 2.. personally I would say it's getting into the range of time and mileage to be doing something about the battery You want to do the repair whack-a-mole thing. Then that's what you'll continue with. I chose not to do that and bought a battery apparently at a good time to do that I spent about $1,400 cash and carry from a Toyota dealer brand new not rebuilt I needed the car more than I needed to play or work or whatever we're going to call it I don't play whack-a-mole at the fair I'm not going to play it in my vehicle I might play it on my lawn mower or something but not in something that I need pretty much daily or I don't eat.

 

Tom, you jerry rig every thing else on your cars and do so many jobs half by procedure and half by how you feel that day. Why so "OEM" on an HV battery? I figured you'd have just dropped in some 6v lantern batteries and called it a day.....

A P0AA6 is completely different from a P0A80.

 

Whatever route you go, be sure to tighten the bus bar nuts to 48 INCH-pounds with a torque wrench.

Posted via the PriusChat mobile app.

 

Yes if you're dumping the car dudu management problems that are beyond your control like check engine lights and cats and you live in places where that can't be rectified with paperwork then of course you have no choice so then no matter oh well made up battery can go 3 to 4 years you'll be out of the car by then for sure

 

It appears that your meter thought so. Its opinion is worth more than mine.

 

You could eliminate the "grounded to the case" by placing a small square piece of electrical tape on the bottom of the module to cover the metal insert. Do not install the mounting screw for that module. The tape will provide insulation between the insert and the case, effectively removing the "ground" condition, just like if you were to use electrical tape to wrap an exposed bare wire.

The wires on the bottom of the battery are for the three temperature sensors (thermistors). typically, these break right at the thermistor if stretched very tight and are not repairable. Happens quite often when the battery is being disassembled and it's forgotten that these are attached to the modules. If one of them is broken off, perhaps that is the source of the P3000? I seem to remember those sensors each having their own code or subcode, but I'd have to look that up again to verify. Another member located a suitable replacement thermistor on Amazon for a few dollars that could be spliced into the wires. The entire OEM wire harness can also be purchased on ebay.