P3020 returns

You can look at the freezeframe data (if any) that is stored - click on the snowflake icon next to the code. That should have battery block voltage values about the time it set the P3020.

You can also monitor block voltages with Techstream while someone else drives. Or you can record data while driving (and review it later).

All of which will likely confirm a faulty module. ie, drops by about 1.0-1.5V lower than others under discharge (heavy accel) and goes higher under charge (decel).

Posted via the PriusChat mobile app.

 

Corrosion at that connector is common and results from cracks in the seam sealer around the tailgate opening in the body. Look around the TG lift ram body mounts, then go up toward the rain channels under black rubber strips on the roof. Little cracks that should be cleaned and resealed.

I would expect a battery fan problem to set a P0A84 in the battery ecu. Dr Prius is handy but doesn't reliably pull codes from both the hybrid control ecu and battery ecu. (P3000 is the HC ecu saying "hey, battery ecu says it's got a problem, you should go over there and check it out.)

Still sounds like the HV battery is weak - you need to look at voltages when accelerating hard (high discharge amps).

You might want to read this thread that reviews several scantool apps and devices - some are fully capable of reading codes and data from all systems on a Gen2 Prius

https://priuschat.com/index.php?posts/3290690

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Well, you can use Dr Prius - it has the "VOLT DIFF" (voltage difference) data line. In general that should stay at or below 0.3V, if it goes higher than that for more than a few seconds (or goes crazy high - say over 1.0V) then the ecu will take notice and eventually set a code.

If you have high voltage difference then you can pay attention to individual block voltage values to see which ones are going too low (or too high).

On the android Dr Prius, you can hit the record button and it will save data while you drive as a .csv file ghat you can look at later.

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Certainly possible.

Me, I would like to see what code is in the battery ecu (and any freezeframe data).

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You use one of the scantools from the link in post #25 - specifically one of the tools capable of scanning all systems. It's up to you to decide if you need functions like reading freezeframe data and INF codes, or having bidirectional controls.

If you read the entire scantool review thread, I specifically mention Dr Prius pulling P3000 (from hybrid control ecu) but not have any codes from HV battery ecu. (I guess it's a glitch in the app?) This must be what's going on with your car.

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Suggest you get techstream, bootleg version on eBay. It's not hard to set up, and has all the functions you'll need

 

My understanding is its rarely "worth" just swapping out modules. Sometimes you can get kinda lucky, but often you don't really know what you are getting when you get replacements. And if the "new" ones are worse or better than the old ones that creates problems. You can get salvage HV bats from some junkyards. If the donor is actually low mileage and low age you might end up with a set of more or less matched modules (of course you have to verify compatibility with your old car). I've found (in LA) these salvage bats are about $1000 to $1500. It's still a lot of work, some of it fairly delicate (meaning you'll break and have to replace various things as you go) and obviously dangerous with around 200VDC. You will get a lot of different, strong opinions about all of this - "fully tested modules", etc. In the end there is no quick and easy fix which is likely to last more than a few weeks/months/days. You'll learn a lot in the process. These bats were really not designed to be "refurbed". Toyota would prefer you crush your car at 150,000 miles. And when dealing with the HV bat buy a new one from them. It can be an interesting, educational process dealing with trying to get a Prius with a bad HV bat back running. But to be sure it's not easy, or fast, although if you shop it can be cheap. Good luck amigo.

 

If you like taking the battery apart every few weeks, over and over again, with the reliability of a twenty year Hyundai, go for it.