Troubleshooting RTOD and traction not engaging

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by digitania, Feb 11, 2020.

  1. digitania

    digitania New Member

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    I need some guidance on troubleshooting an issue with my 08 Prius.

    Last night when driving home I got the red triangle of death, the ABS and VSC lights all at once. I got home and shut off the car and tried to restart it, and it would not go READY; rather, all the warning lights came on and stayed on, and I got the red triangle of death on the MFD as well. Car will not engage in D or R.

    The car has 140k miles on it. The traction battery was professionally replaced with new about seven months ago, and consistently hits the green or top of blue on the monitor. The 12v battery replaced less than a year ago; multimeter shows 12.8V at the terminals on it. Inverter coolant pump is working and moving coolant, though from the descriptions I've read I expected it to move the coolant more swiftly than I'm seeing. I can hear and see the pump run.

    I can clear the codes by disconnecting and reconnecting the 12V battery, and the car will go READY and I can engage the drive in D or R but it will set the code again after about a minute, with the same symptoms -- as long as I don't turn the car off it will engage and drive seemingly fine, but turning it off and back on again yields the same issues I describe above.

    I do not currently own a code reader and don't have a lot of time to wait to receive one, but may be forced to or forced to take it to my local Toyota deal for a diagnostic -- which I'm willing to do, but only if it's safe to drive with this condition -- I can't afford to damage it right now. I'm willing to go buy a code reader at my local auto parts retailer but am unsure what model to buy. I gather that the auto parts store's 'free check engine light scan tool' will only do OBD-II code reading and may not pick up codes that could point to the source of the issue.

    Questions arising:

    1) Should I go ahead and drive it to the local auto parts store for the 'free' scan and see what it says? (About 1.5 miles)

    2) Should I forgo that and just drive it to the Toyota dealership for a diagnostic? (About 5 miles)

    3) From what I've read on this forum and elsewhere the 12v battery or the inverter coolant pump are the 'usual suspects' for these particular symptoms, but both appear to be functioning fine. I've had no serious issues with the car before now; I replaced the traction battery simply because the car had sat basically unused for almost two years and the traction battery would not hold a charge well (I never got an error code from it, but left overnight it would lose charge from 5-6 bars to 1-2 bars on the monitor, and I couldn't afford to have it strand me as I started driving it regularly for a new job about 700 miles/week). Other than normal maintenance issues, I've had no serious issues with the car since I started using it again about eighteen months ago... and this came on without any warning at all, on a chilly evening. Is it *possible* for the inverter coolant pump to be *weak* and not circulate coolant fast enough, and therefore create this issue? See my comment above about coolant circulating but not as vigorously as some of the posts I've read here seem to suggest it should... is the code set due to non-function of the pump (electrical) or is there a sensor that detects the flow of coolant and would trigger an alert if it doesn't flow *enough* (like a Mass Airflow Sensor)?

    4) Is there an off-the-shelf code reader that folks would suggest that is compatible with a Prius and is readily available from a brick-and-mortar retailer like AutoZone? I know about the suggested MiniVCI but I may not have time to wait on one. (Of course, I may have no other option.)

    I may be left with no choice other than to bite the bullet and get it to my local Toyota dealer for a diagnostic, but I *hate* being left with only that option if there's another course of action someone might know of. I've tried what I've been able to find on this site and with Google searches but they keep coming back to what I've mentioned above, and none of which seem to be an issue based on what I can determine with what I have on hand...

    Thanks for assistance in advance.
     
  2. dig4dirt

    dig4dirt MoonGlow

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    Sorry to hear the problems. May be something quick and easy fix or may not be.

    How long have the car been sitting undisturbed until you check the volts of the 12v batt?

    Have you any clue what type of traction batt was installed? Professional as in Toyota? Or aftermarket? Any warranty?

    Not sure auto parts store can read specific prius codes but may be worth a shot if not out of your way...maybe a phone call first?

    You could get a Bluetooth odbii and also download app such as Dr prius or hybrid assistant to read codes.


    Other folks can give you further ideas.

    I will mention that going to your local Toyo dealer is not your best first option unless you can write checks from an unlimited funds account.
     
  3. davecook89t

    davecook89t Senior Member

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    The answer for this is: we don't know. According to the Repair Manual, the "Typical Enabling Conditions" and "Typical Malfunction Thresholds" for a code P0A93 (which is the code for a malfunctioning inverter coolant pump) are "Toyota's intellectual property", so the the best guess is the code could be thrown by either an electrical or mechanical problem.

    We had a P0A93 on our Gen 2 last year, that I was able to read with a ~ $15 code reader with the ELM 327 chip and the Torque app on my phone. Although the Mini VCI with Techstream is the preferred solution for reading codes, that usually requires a little more time and effort to implement. The ELM 327 readers are available online for little money, but the auto stores don't seem to carry them, probably because there is not enough profit in it for them. If you are really insecure about driving your car even for a few miles, your best bet might be to have such a device shipped to you overnight. With Dr. Prius or Torque Pro you would probably be able to detect all the important hybrid codes, so you would have an idea which part of the system is giving you a problem. Apparently some of the sub-codes (which would help you narrow down the problem even further) are now available through Dr. Prius and perhaps others.

    Without any other information, the inverter pump is probably the best candidate as the source of the problem, as you have speculated. A short drive to the dealer without a functioning inverter pump would not hurt the car, as I can attest, but you should probably not be staking the well-being of your car on some advice from a stranger on the internet.;)

    That certainly wouldn't hurt to hopefully save the drive to the dealer.
     
  4. digitania

    digitania New Member

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    I checked the 12v battery about 12 hours after the initial issue (which happened very late last night, too late to work on it). This also after several attempts to reset computer, doors open, etc.

    The battery was replaced less than a year ago with an Optima yellow top and I've had zero issues with it. The only time I've had to do anything with it since replacing it was a few months ago when my HUD and SAT radio both quit -- the known capacitor issue with the HUD, and apparently the SAT radio has the same issue because it started working again after disconnect/reconnect of the 12v battery.

    It was done by Greentec Automotive in the Dallas-Fort Worth area, a hybrid specialist. New rather than rebuilt with a four-year warranty.

    Already done. They said their readers could not read anything other than OBD-II codes. I spoke at length to the manager at my local AutoZone, where I do most of my parts business. He said he knew their 'free' readers would not pick up anything other than OBD-II standard codes and might miss a hybrid-specific one. Called other providers nearby; same story.

    I checked the 12v battery about 12 hours after the initial issue (which happened very late last night, too late to work on it). This also after several attempts to reset computer, doors open, etc.

    The battery was replaced less than a year ago with an Optima yellow top and I've had zero issues with it. The only time I've had to do anything with it since replacing it was a few months ago when my HUD and SAT radio both quit -- the known capacitor issue with the HUD, and apparently the SAT radio has the same issue because it started working again after disconnect/reconnect of the 12v battery.

    A fact with which I am painfully familiar. It will be my action of last resort, but may be dictated by circumstances.

    Thanks.
     
  5. digitania

    digitania New Member

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    Thanks for your input. I appreciate your candor.

    My understanding about the state of the coolant in the tank under normal conditions is that it should be moving 'vigorously'. This is more like 'gently'. One can see it move, but it is not obvious.

    I did pull the headlight to access the pump and actually removed it. I checked both the power connector to the pump and the pump itself. It *did* seem to me that the pump was not as loud as I've heard it be in the past, which makes me wonder about how the error condition is set.

    I have not had an issue to this point that warranted my buying a scanner. I think I'm going to have to do so now. I don't mind spending <$100 on something like that; it would be useful. I just don't want to spend $200 on a part that ends up not addressing the issue... and have to take it to Toyota anyway.

    If I can manage to afford the time, then maybe I can order the Mini VCI device off eBay with the software, and order the pump online as well (Toyota dealer here quoted me a $195 price for it. I am leery of a non-Toyota-branded part for something like this). I just don't know if I can. Will have to see.

    Again, thanks for input. Will keep everyone posted.
     
  6. TMR-JWAP

    TMR-JWAP Senior Member

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    @digitania

    You have a P0AA6 HV isolation fault. It's THE ONLY fault that gives those symptoms of allowing you to drive the car normally until you turn it off. Once you turn the car off, it will not go ready again until you clear the code, which is what you're doing when you disconnect the 12v battery.

    Most often, this is caused by the HV battery having an electrolyte leak in one of the modules, which provides a path for high voltage to pass to the car chassis.

    There are 6 possible subcodes to provide further isolation information. In the big scheme of things, it could be anywhere from the battery to the transaxle, even possibly the AC compressor. Anything at all that is causing a loss of isolation between the HV system and the car body. There are videos online of how to determine where the problem is, based on when the RTOD triggers as you go through the startup routine. I've never used the video way, so I can't attest to the accuracy.....

    You may want to get the codes/subcodes and/or call the place that replaced your HV battery. Maybe they offer diagnostic services. You'd like to think they would know more about the Prius than a random guy at AutoZone. Dealer would be best, but also most expensive.

    And...a P0A93 will never prevent you from restarting the car after it has cooled down.

    And....Gen 2 was the only Gen that prevents going ready after this code. The other Gens will still let you go ready. MANY people will just continue driving and merely reset the code as needed or disconnect/reconnect the battery as needed.
     
    #6 TMR-JWAP, Feb 11, 2020
    Last edited: Feb 11, 2020
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  7. digitania

    digitania New Member

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    Thanks for your input... however, in this case, I can't restart the car hot *or* cold. Only after I clear the code. I let it sit for 8 hours overnight in the cold, cleared the code, and it started right up - then set the code again. Shut the car off immediately, then back on -- no go. It was not hot at all.

    I'm going to call the place that serviced my battery tomorrow. They came recommended to me, and seemed very knowledgeable about all things Prius, so I'll see what they have to say. It will be difficult for me to get the car back to them since it's 250 miles away -- there is not a hybrid specialist near me that was recommended -- but if it's safe to drive with the codes set, I'll do it. However, if I have to reset the battery every time, that will get old very quickly.

    As I mentioned, the RTOD triggers within about 60-90 seconds after clearing the code and restarting the car, even if I just leave it in READY and not engage the drivetrain. I will look for the videos you suggest for diagnostics. Thank you.
     
  8. davecook89t

    davecook89t Senior Member

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    I'm sorry to have thrown the P0A93 into the mix. It would not prevent your car from starting as the P0AA6 will do. That is a more complicated problem, for which you will need the sub-codes. Probably the cheap ELM 327 reader will not provide them. It looks like you will need to get the Mini VCI, if you don't want to pay the dealer, but your first option should be trying to get Greeentec's help, since they need to prove to you that it is not the battery that has the ground fault.

    I'm glad @TMR-JWAP felt the need to set you on the right path after I had misled you.:eek:
     
  9. dolj

    dolj Senior Member

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    It doesn't matter if the car is hot or cold, so yes, it will only start when you clear the code.

    You will need to pull one of the battery connections every time you want to start the car and I agree that would get old very quickly.
     
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  10. George W

    George W Active Member

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    As previously mentioned, the code readers are very little money ($12). Here is one I use which hasn't let me down. Additionally, with smart apps like Torque Pro, you can reset your hybrid codes on the fly. With Dr. Prius you can reset your battery code on the fly.

     
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  11. edthefox5

    edthefox5 Senior Member

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    What’s a professionally rebuilt battery?

    Any and all “rebuilt battery’s” are suspect. Rebuilt means they just replaced the failed module with another 12 year old module that has just not failed yet.
    And anyone who does that will not do a excellent job on the repair which is replacing all the rotten interconnect and charging and discharging all the existing battery’s and load testing them all properly to see if there are any more ready to fail.That takes days and days. It’s quite a racket on Craig’s list. We call it whack a mole repair

    Only battery you can install and count on is a brand new factory battery they have brand new cells. $$$$$$

    New factory individual repair cells are not available. Best repair option is a seller here on this site sells Brand new aftermarket cylindrical cells that fit in the original case. $1600 u install.

    You most likely have a ground fault nag on your hybrid battery.
     
  12. digitania

    digitania New Member

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    No, not rebuilt. All new cells, with warranty.

    Thanks to all who have offered input. I have ordered a Mini VCI so that I can diagnose it further. I will be traveling over the next couple of weeks so I can leave the car parked, and hopefully it will arrive before I return so that I can delve into it further.
     
  13. edthefox5

    edthefox5 Senior Member

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    Cool so it’s a brand new battery installed by a Toyota dealer.
     
  14. digitania

    digitania New Member

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    If that's what the posts above tell you, then you're welcome to think that. I explained it clearly.
     
  15. George W

    George W Active Member

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    Techstream will require an obsolete laptop running XP or Win7.
     
  16. TMR-JWAP

    TMR-JWAP Senior Member

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    There are versions available that run on 64 bit computers. I have two laptops, one 64 bit and one 32, each with their own version. I actually prefer the one on the 64 bit computer, as it seems to run the full health check significantly faster.
     
  17. digitania

    digitania New Member

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    Obsolete with respect to hardware or software only? I'm an IT guy by profession and have most versions of Windows released in the past 20 years available to me. The hardware might be a little trickier, but I do have a few older laptops at my disposal -- 'older' being a relative thing... :) Thanks for the heads-up, though.

    The Mini-VCI actually arrived today, so if I have time to mess with it before I leave, I will...

    Thanks.
     
  18. digitania

    digitania New Member

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    Good to know. As I mentioned, I literally just received the Mini-VCI, so I'll put my hands on a laptop with Win7 to start with and see what success I have. I've seen references to installation guides for TechStream, so I'll use those as guides if needed; however, if you have any specific recommendations I'll certainly take them.

    Thanks.
     
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