Dreaded code P3009

DTC P3009 means that your car has a high voltage ground fault. The problem could be anywhere in the line of components that are subject to high voltage: traction battery, traction battery ECU, the battery cable leading to the inverter, the inverter, and the transaxle.

It could be that the tech did the necessary fault isolation to determine that the battery was the actual cause, and it also could be that he guessed. You may wish to inquire into exactly how the tech determined that the traction battery is the failed component.

There is very little chance that the warning light is a fluke. You'll see it again soon. It is possible that high ambient humidity worsened the ground fault problem.

The Classic can be driven indefinitely with this fault; however if your car gets into an accident and the other side of the high voltage line contacts the body then this would cause a definite safety issue.

 

Hello David and others,
I have a similar situation currently unfolding. The master warning light came on on a very hot and humid day. Took it to my Toyota dealer and the code that came back was "P3009." The car is 2002 model. I am concerned that the P3009 code may actually be something else and not the battery. The car starts and runs fine, except for the master warning light. Toyota says I need a new replacement battery, and the car is in their shop. I have asked some questions based on this thread and others, but still not really clear how diagnosis was determined and whether P3009 indicates a new HV battery, or possibly something else. Any suggestions? David, if you are still reading this thread, how is your Prius doing now a couple of years later. Did you experience any other problems? Thanks.

 

Welcome to the club and good hunting restarting this thread:

Humidity . . . something that the hydroscopic (water loving) electrolyte in the traction battery modules loves. With enough humidity, it can form a high resistance path to ground. It is the harbinger of things to come but as Patrick pointed out earlier, you can drive with the problem. It is a 'warning' that something needs attention.

Although possible, it is improbable given what we've seen in the past. Testing is pretty involved using an unusual, high-voltage test instrument called a "MEGER", a high voltage insulation tester.

Are you 'technical' enough to want to try diagnosis? We're more than willing to help you get started.

First let's find out if this is intermittent or a constant condition by clearing the code:

• disconnect the 12V ground for 30-60 seconds - this is a power reset and clears all codes
• start car and see how long the error indicator comes back
  • Follow Chapman's excellent protocol - ON but not READY to divide the problem in two.

Consider getting a Prius-aware scanner so you can read out the code and subcodes:

• XHorse miniVCI - around $35, you'll need a Windows PC, like a laptop, with Windows XP (preferred)
• ScanGauge II - around $150, you'll need to add XGAUGE definitions similar to sending a cellphone text message
• AutoEnginuity - around $500, you'll also need a Window PC, any OS, it is a shop-quality scanner
• TeschStream-Lite - I am not sure what this really cost as I've heard some pretty high prices for the Mongoose cable and some from of software 'rental' but it is pretty much what the dealer service department uses

Also, consider getting the vehicle maintenance manuals. They show up from time to time on Ebay, the paper copies. There is a two volume shop manual and a single volume schematics manual. Start with Volume 1 as this has all the codes needed to diagnose a problem and procedures. Volume II is more about the mechanics of replacing or fixing problems.

GOOD LUCK!
Bob Wilson

 

There are a bunch of potential P3009 causes, some entirely outside the battery, some inside the battery but correctable without buying a replacement battery. Before you sign up for $2-3k of new hardware, I'd strongly suggest dropping fifteen dollars at techinfo.toyota.com (if you don't have your service manual already) to look up what the procedure is to diagnose which of the roughly eleven possible causes is at fault. I'd recommend this even if you're not a DIYer and have no thought of working on it yourself - it will help you understand what you want a mechanic to be doing for you on this problem.

You'll find the P3009 diagnosis steps around pages DI-331 to DI-338 (pages from my 2001 book, 2002 could be different) - that's eight pages of decision-tree steps to work through in tracking down your problem. The first test is so easy you can certainly do it yourself if you have a way to clear the P3009 code:

With ignition ON, clear the code. Turn ignition OFF. Then turn it back ON (but not to START, do not make the car READY), wait one minute, and check whether the P3009 is back. This test will distinguish what's on one side of the system main relay (all the stuff inside the battery case) from the other side (the power cables, inverter, and transaxle). If the code comes back while the car is not READY, the fault is on the battery side. If it doesn't, it must be on the cable/inverter/transaxle side (assuming you still have the same conditions, humidity etc., that brought it on the first time).

That one test will leave you about half the decision tree still to work through either way, the cable/inverter/tranny half or the inside-the-battery-cover half. The next steps aren't as easy, they will be time-consuming and the inside-the-battery-cover steps involve exposure to high voltage and possibly potassium hydroxide. But several possible causes can be found there that would be easily corrected. Getting there requires going under the trunk trim and into the battery, with all the necessary precautions, so it's about equivalent labor-wise to battery replacement. What you could stand to save is the cost of the part.

Sadly, from what I've seen of the world, you're unlikely to find any mechanic employed in a shop who will invest that kind of effort in a diagnosis (unless working on his or her own car) when it's just as fast to swap the whole battery and the $2k won't come from his or her pocket. The shop economics just weigh in favor of selling you the part swap. This can be a real economic downside to the trend from self-reliant DIY culture to take-it-to-the-shop culture.

Let us know how it turns out! The previous poster's experience might or might not have much predictive value for yours, because we don't yet know whether the source of your P3009 is the same as his was, and that's what will matter.

Hope this helps,
-Chap

Heh, I see Bob slipped a reply in while I was writing this. You could combine the test I described with the one he suggested: if the code comes back with the car ON but not READY, we know to look on the battery side of things. If it doesn't, then either it's on the rest-of-the-car side of things, or it's just intermittent and not coming back right now. That's where Bob's test with the car started would settle the question if the code comes back then.

 

Thanks guys! The info provided is really helpful to my understanding of things. I am surely not tech savvy enough to do the diagnosis myself, but this info helps me with information I can take to the dealer in the form of questions. My greatest concern is shelling out $3000 plus for the new battery, and a short time later getting the lights/warnings again and having it be a different diagnosis (transaxle, etc). I have alteady raised my concerns and questions thus far, but not much info in return as to how thier "diagnosis" was made. All answers are given to me in very general language with no specifics. It's possible they just saw the "P3009" code and made the detrmination I needed a battery. It has not been explained to me any further steps that were taken other than 3009 appeared twice- though I am not sure the steps you outlined above were utilized. But you have given me info I can use to ask further questions tomorrow. Thank you for being so responsive so quickly. One other quick question. If the 12v battery was "low" and it was a humid day, do you think this could cause a "misread" of the P3009 code? In other words, with a new 12v and cooler weather could the problem (assuming there is one) correct itself? It may be a silly question, but I just have this nagging feeling about it. Last time I was at Toyota I wanted to replace the 12v feeling it was "low" b/c if lights were left on a short while (5 to 10 minutes) the 12v wore down and car wouldnt start. It took a jump immediately and was fine thereafter. But this happened twice in the course of a month. When I inquired about it, the 12v battery was tested and I was told by Toyota it was fine and no need to replace it, even though I really felt it might need it. It is the original 12v battery and is over 11 years old! Fast forward a couple of months and I am driving on a warm humid day and the warning triangle lights go on, followed by the P3009 code, which brings us to my current dilemma. There may be absolutely no connection. Just asking your thoughts. Thanks again for all your help!

 

There are plenty of reports on here about the various computers in the vehicle showing spurious codes or other strange behavior if the voltage on the 12v system has fallen especially low. Generally the cure is to (a) get the battery recharged to a strong 12+ volts, then (b) disconnect it for a minute or two then reconnect it, so the computers all get a clean reboot on correct voltage. That could have happened to you once. But if you've done that, and the voltage hasn't been going below 10 or 11 volts since, and you're still seeing a code return and it's consistently the same code, I'm guessing that's not your explanation. Also, if humidity seems to bring on the code ... to me that increases the likelihood there's a genuine HV leakage path somewhere. (Have you ever walked past utility poles in soggy weather and heard faint sizzling sounds from up atop the pole? Same deal.)

For your peace of mind, you might want to measure the voltage of the 12v battery some morning when the car has been sitting a while and before you start it. If you don't have a voltmeter at hand, there is one built in to the multifunction display, which you can get to with some 'easter-egg' screen taps described elsewhere in this forum. (There's also one built into a ScanGauge if you have that, or probably any other OBD-II scanner - it doesn't rely on computer communication, it just measures the 12v pin at the connector where you plug it in.)

Check the voltage with the key turned ON (but not as far as START, car not READY). You could then add a few things like headlights, wipers, heater fan, etc., and see how much it drops at each step. Then let us know what you see.

-Chap

 

I agree, If your 12V is weak and/or old, replace it. A weak 12V can cause all kinds of trouble with the Prius computers, and leave you stranded on a cold morning.

More P3009 tips to determine the problem area are here; Easiest way to confirm P3009 error source | PriusChat

 

exactly same symptoms exactly same code exactly what happened to me :-(

 

thanks to your post I just bought a 2 day subscription to the manual for my 2002 prius this exact problem code P3009. I am glad I did. Before I go into more detail I have to tell you I did test the car just like you recommend in this post and error code P3009 only comes when the engine is ON (running) and I immediately put into Drive gear. If I leave in P (after resetting) the error code does not come up. I am assuming thats because my problem is with (the power cables, inverter or transaxle)?

Now I'm trying to figure out how I can safely and cheaply pin point, which one of these is my actual problem and if it's even worth DYI-ing... This prius is an extra car we have and I've always wanted to sell it but now with this ERROR code Im not sure how much I can get for it.

 

Hmm, I wonder if the next step would be to isolate the motor windings from the inverter, and test them with a megger.

-Chap

 

That screen tap thing only works on gen II s. Am I missing something here?

 

I've never owned a Gen 2. I've owned a Gen 1 and a Gen 3 and used the screen tap thing on both.

I've also used it on Gen 2s that I didn't personally own.

 

In a Gen1, which screen do you need to be in to get it to work? Display screen?

 

IDK, but it's in the service manual that I have a copy of. Shoot me an email and I'll send it to you.

 

This week, in my gen1 186k, after some heavy rain and water now in the spare tire well, I got the P3009. Having put a dehumidifier in the car and running it overnight, the code stopped happening.

I am somewhat confident that the hv battery is ok as I had pulled it last Oct '23. Local shop said the battery was toast with 6 bad modules. Recommended junking the car or do a battery for 2k. Had a line snapped error.

Replaced corroded bus bars, hv cables, and computer for about $300. All modules tested ok, though 2 are on the low Side.

Have gotten 5k more miles since then.

Bill

 

You might just leave one of the drain plugs out in the spare tire well if water is a recurring problem. It also fills the passenger-side cubbyhole in the trunk, but no drain hole. Maybe drill a hole in that to drain.