Red triangle during the idle calibration "dance". Straight after 12V replacement,

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by uart, Feb 29, 2020.

  1. uart

    uart Senior Member

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    Hi all, I've been absent from the forums for a few years. Good to see a lot of the old familiar posters still here. :)

    My current problem :

    - I just replaced my 12V battery after the old one died suddenly yesterday.

    - No problems there. I did it myself and the new one is showing good voltage levels (both when running and when off).

    - First drive after changing the battery I tuned the radio and set the clock and everything seemed totally smooth.

    - Right up until it was fully warmed up and I stopped at a set of lights with the engine idling. It started doing it's usual Gen2 calibration dance, where it normally idles for about 8 seconds before cutting the engine out. But after a few seconds the Red triangle exclamation mark and "problem" lights came on.

    - I pulled off the road and turned it off and on again, but the warning lights remained. I also checked the oil and fluids and serpentine belt, and everything looked perfect.

    - I then had to drive it about 12 km home with all the warning lights on, but surprisingly the car seemed to behave perfectly. Engine power was normal, battery charging and EV running was normal, MPG was excellent. I really couldn't detect any problems, but the big triangle and !problem! warnings remained.

    - When I got back home I pulled the little plug with the single white wire at the 12V battery terminal block (and old trick I learnt here to reset the codes without disconnecting the battery). This reset the codes, and surprisingly they have not returned (driven about 100 km since).

    - BUT, there is one remaining problem, and once again it is related to the little calibration dance that the Gen2 does after it warms up. Instead of cutting out the engine after about 8 seconds as it used to do, it now takes about 40 seconds every time!

    Just wondering if anyone else has experienced anything like this after 12 battery replacement? I'm wondering if it's just some dodgy data in the system somewhere after the 12V failure (it was down around 7 volts and my wife was trying to start it with relays dropping in and out and sounding very unhealthy), and if maybe it will just sort itself out after driving it for a few weeks?

    Unfortunately I don't have a scan gauge or similar to check for codes, but all warning lights are staying off and the car appears to be otherwise running perfectly.
     
    #1 uart, Feb 29, 2020
    Last edited: Feb 29, 2020
  2. JC91006

    JC91006 Senior Member

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    I'd suspect your hv battery is causing the issues. If you have a scanner, you probably would pick up codes relating to the hv battery.
     
    Raytheeagle likes this.
  3. uart

    uart Senior Member

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    No I don't think so. The HV battery was replaced (with a new one from a dealership) a few years ago and it has been performing flawlessly.

    It runs without any problems in EV mode, and the SOC seems to be behaving totally normally (charging and discharging as expected with no rapid fluctuations or anything). It really seems to be running perfectly apart from that one strange issue.
     
  4. JC91006

    JC91006 Senior Member

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    Have you checked the inverter coolant pump? see if it's working? Open the inverter pump reservoir and see if the fluid is moving rapidly when it's in READY mode
     
    uart likes this.
  5. uart

    uart Senior Member

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    Yeah I should have mentioned that JC. I pulled over and checked that as soon as it first popped the warning lights. Oil, coolants (both), inverter pump flow, serpentine belt and 12V battery voltage. All were perfect.

    The warning lights seem to be staying off for now. It's just that I suspect something is still not quite right as it still doesn't do the idle check and cut off the engine properly.
     
  6. JC91006

    JC91006 Senior Member

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    I would only suggest you read the code when it comes back. The basic stuff you've covered so it can only be something that the computers are picking up. From my experience when the idle is not right, it points to the batteries.
     
  7. valde3

    valde3 Senior Member

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    My guess would be a dirty throttle body. Disconnecting the 12v battery will loose the idle calibration. It will then move around to find it and is getting stuck because of dirt.
     
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  8. uart

    uart Senior Member

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    Just an update.

    After a couple of days driving (about 220 km) it seems to have come good all by itself. It looks like my Prius is just a slow learner, but at 15 y.o and 383000 km I think I can forgive it for that. :)

    Last night I had a few errands to run, and it let it cool a little between each trip to make sure that it had to redo the idle thing. Each time it got better and in the end it was cutting out the engine in about 5 to 8 seconds of idling, which is totally normal in my experience.

    Now my lead footed wife has taken it to work today, so it's sure to get a good "Italian tune up" as well.
     
    #8 uart, Mar 1, 2020
    Last edited: Mar 1, 2020
  9. valde3

    valde3 Senior Member

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    That's almost surely caused by a dirty throttle body. If you decide to clean it at some point reset it at he same time and you don't have to wait for that long for it to relearn the position again.
     
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