2009 not going into gear, several codes

That's the process I'm completing now, with assistance from TMR-JWAP. So far, I've confirmed 62.6V leakage from the positive HV battery relay post to ground. So now I'm going to uncover the battery, remove all the bus bar straps with the battery still mounted to the body, and test for voltage leakage from each of the 28 7.2V modules to ground. That will hopefully ID the individual module(s) that are leaking electrolyte and causing the loss of DV voltage isolation to ground. Then I plan to pull the battery pack out of the vehicle, inspect everything else in the process, especially that problematic orange connector plug (the one with pin #22) on the battery ECU. Will also look for corrosion in general, and on all the other connector plugs, in particular.

Will hopefully find and replace one or more faulty/leaking 7.2V modules. Then get it all back together again, up and running DTC code-free! That's the tentative plan. Will probably continue work on it today. Happy New Years day!

 

So I guess you have spare modules lying around the chargers and whatnot so you can charge and discharge these things and play around till one's content. That's great. But I need the car everyday so my answer was just to buy a known good rack of sales preferably new untouched... from the manufacturer. Now I have three racks sitting around here that I can just piddle around with whenever I get ready none of mine have any leaks they're just I guess dead The racks look perfect and everything looks great there's no puddles anywhere looks like anything spilled or burnt any metal The ECUs and all that look great All I had was battery failure codes in these . Maybe I'll get to play with them someday maybe not

 

Feel free to send them my way, if they're just collecting dust!

 

Here's a pic showing the leaking module in my HV battery that was communicating 6.72 volts to the steel battery box. Now I need to pull the HV battery and replace this module, in order to rid my Prius of the DTC P0AA6-612.

 

Prior to separating all my modules, and with the orange HV battery disconnect unplugged, I had 62.4 V leakage from the positive main relay terminal to the steel battery case.

Then I removed all the bus bar caps from the individual modules. My individual modules were reading 7.87 V on my Volt meter. Even the leaky one. But not sure that's too relevant Your car hasn't bee run recently so your HV battery could just have lost some voltage over time.

I detected only one module leaking voltage to the battery case. My #9 module (from the HV ECU) read6.72 V to the steel battery case. I could see no electrolyte leakage seepage anywhere. But it must have been leaking voltage from the female steel threaded ferrule used to bolt it down the base plate.

I wouldn't think a 0.4 V reading would mean much of anything. Because I had 0.1 to 0.3 V readings on a number of modules. Could be a difference in my Volt / Ohm meter calibration, compared to yours? You sure you had your Volt meter on DC voltage. I was scratching my head for a short bit before I realized my Volt meter was set on AC voltage... Once I set it to DC voltage, no more confusion!

I'm no expert on this subject, other than the 24 hours I spent researching my DTCs, and finally pulling apart my HV battery. The only one I've ever been into. Maybe others will more experience will sound in and give you some further assistance.

 

Good work finding your fault. Yeah, now the fun part begins.

The most reliable (and $$$) would be to replace all the battery modules with a new set from Toyota (or aftermarket from someone like NewPriusBatteries.com). This should provide 10+ year reliabilty. I believe that the folks who made the Dr Prius app have marketed a new Li-Ion pack as well. No one sells individual new modules.

Generally not many here will recommend a rebuilt or refurbished pack as quality varies alot. Usually isn't that much cheaper than new. Since the modules are used to begin with, you might get 2-3 years at best. Understand the warranty terms because you will likely need to use it.

You can try to "just" replace bad modules as needed. Problem is that the battery capacity likely isn't the same between the modules you have and the ones you get. As the batteries age they degrade, and not always at the same rate. So what install might have the same voltage as the rest when you install it. Those voltages can go higher or lower than the others during use (when the pack is charged and discharged)- if those voltages get too far apart (too much differential) then the ecu will throw "replace battery pack" P0A80 and - or "block number xx reads weak" P30xx codes. Based on the posts I see here, you have about a 10% chance this could work.

Next would be to replace the bad modules and then perform discharge and charge cycles with either a "grid charger" (does the entire pack at once- but you can't evaluate individual modules), or by getting (multiple) hobby RC chargers to cycle each module separately (takes much longer but you can find most weak modules). Search the forums here to find out more about both options.

Either way of cycling requires more knowledge, tooling, and time than just replacing the pack. If done right it has a much better chance of being a "good" repair, but still might be 1-3 years more. Done wrong and the car might not start or throw codes the next day, week, month.

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I'm currently working on an original battery from a 2008 I purchased that had a ABS code. Totally virgin battery. I bought it back in January 2021 while in Myrtle Beach, but never really got a chance to do anything with it until now. I drove it from MB to Columbia when I purchased it and had no problems other than the brakes were a bit grabby at very low speeds. Fast forward to about a month ago, I drove it a bit and it coded with a P0AA6. Reset via 12v battery disconnect and drives fine again. Codes out again whenever. Rinse and repeat.

Decided to play with it last weekend. Here's info I got.

With the disconnect installed, I had 112v between the (+) relay terminal and the case, 37 volts between the (-) terminal and the case.
With the disconnect removed, the (+) terminal reads 5.5 volts and the (-) terminal reads 13.1 volts.

Removed the battery from the car and put it on the work bench. Very similar readings when I did it again on the bench.

Removed the cover and the electronics section. Had difficulty getting the wire harness unplugged from the ECU. It had some pretty significant corrosion on the usual ECU pins, but it was still letting the car be driven. Also had 3 very obvious areas on the case that at first glance looked like electrolyte leakage corrosion areas.

I removed the sensor harness and all bus bars. I measured every module terminal, and guess what I found? None of them had any voltage to the case. Zero, NADA, nothing of any significance. Every single terminal would show 0.1 or less and immediately drift to zero in a second or two. I've never had that happen previously, so it's something new to me. Best guess? The corrosion in the plug socket at the ECU.

I never even unbolted the modules from the case and have been cycling them all week. Been letting it rest after yesterday's last cycle and plan to assemble it tomorrow. We'll see if the voltage readings change with a new harness and different ECU.

 

Which one had the 0.4 volt reading? When you measure at a relay, the measurement will be the total summed voltage of all modules between the relay and where the leak is. Once you remove the busbars and start doing individual module measurements, all the good modules between the relay and the leak will read 0. The bad module will have a reading less than 8 volts, because that's about the maximum voltage you can have for one module.