Red triangle comes/goes, traction battery ok, drives ok

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ironandsteel, Jan 30, 2025 at 6:52 PM.

  1. ironandsteel

    ironandsteel Junior Member

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    black2005_1_30_2025.jpg I could use some debugging help.

    2005 Prius, 283k. Professionally rebuilt battery installed about a year ago. Recently it started doing this: It drives fine, but every minute or so it will throw the red triangle, and then the triangle goes away. It stays on for 2 - 30 seconds.
    I have not run Techstream yet (I have misplaced my minivci cable), but Dr Prius and FIXD do not report any codes. The car drives fine. The brake indicator remains on, even though the parking brake is off. Could this be related?

    Dr. Prius battery monitor shows it looking pretty good with a Voltage Diff of 0.17v or so, which is pretty reasonable.

    I have 3 2nd gen Prii and have rebuilt batteries over the years and have a lot of experience with these cars. I've never seen the red triangle come and go like this.
     
  2. saneesh8

    saneesh8 Junior Member

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    May be something else. Can you scan and check?

    Possibly it is the ABS..

    Good to know the car lasts this long. Mine is at 150k.
     
  3. ChapmanF

    ChapmanF Senior Member

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    What's the oil level on the dipstick?
     
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  4. ironandsteel

    ironandsteel Junior Member

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    I have a 2007 with 381k!
     
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  5. PriusCamper

    PriusCamper Senior Member

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    Can you look at the voltage difference between battery blocks during high amp loads like hard acceleration or hard braking? You might have a much higher voltage difference.

    But I tend to agree with people pointing towards braking system because they can store codes via blink codes rather than OBD2.
     
  6. JC91006

    JC91006 Senior Member

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    professionally rebuilt battery doesn't have much meaning, it's a used battery that can fail

    I suggest you get a better scanner. You either have a battery failure or possibly a brake actuator failure.
     
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  7. ironandsteel

    ironandsteel Junior Member

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    I can run techstream, if I can put my hands on my minivci cable that is somewhere in all my stuff in my barn.
     
  8. ChapmanF

    ChapmanF Senior Member

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    There's not really a "rather than" involved. The brake system stores OBD-II trouble codes to be retrieved with a scan tool; it's just that there are also blink codes that correspond to those trouble codes, so if you do not have a scan tool handy, you can have it blink out the codes. The repair manual shows the OBD-II trouble codes and the blink codes together, like "C1345/66". If you have that code, a working scan tool will show you C1345, or you can get the blink codes and the ((!)) light will blink six times, pause, and six more times.

    Blink (a/k/a Flash) Codes – How to. | PriusChat

    There are some other ECUs that also can do blink codes, like the tire monitor and the airbags.

    But if you have any codes that you could get as blink codes, you should also be able to see them as OBD-II codes as long as you've got a working, Prius-aware scan tool.

    The only time I know of that the red triangle comes on without a hybrid-system DTC being set is when it is telling you about low oil pressure. For that case, there should also be a small drippy-oil-can icon superimposed up near the top over whatever's showing on the MFD, but it might not be something that jumps out at you if you're not watching for it.

    [​IMG]

    Low oil pressure alerts are often seen briefly, like when you turn a corner and the little puddle of oil that's left in the engine sloshes away from the pump intake for a moment, but then sloshes back after you're around the corner, and the light goes out again.
     
    #8 ChapmanF, Jan 30, 2025 at 9:29 PM
    Last edited: Jan 30, 2025 at 9:37 PM
  9. PriusCamper

    PriusCamper Senior Member

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    Well, in my 'how long will original brake pads last experiment' that ended last Spring at 295K miles when metal on metal turned to the remains of the brake pad falling out while parallel parking on a steep slope, there was a red triangle and there were zero error codes via OBD2 reader with Car Scanner (ELM) app, as well other apps. It was only through the blink code method that I was able to read the codes and clear them after pads and rotors were replaced.

    So when you say that the brake system error codes can be retrieved via OBD2, please identify what app and what error codes you have retrieved via an OBD2 app?
     
  10. mr_guy_mann

    mr_guy_mann Senior Member

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    Well, I started this thread about scantool apps and devices for smartphones almost three years ago. The summary is at post 37. The more capable apps can scan all systems for all codes (including INF sub codes)- and have additional functions as well - such as ABS brake bleeding.
    https://priuschat.com/index.php?posts/3246758

    Posted via the PriusChat mobile app.
     
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  11. Brian1954

    Brian1954 Senior Member

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    I use Techstream and Autel AP200. Both of these scan tools can communicate with all the ECUs in a Prius. The Car Scanner ELM app can NOT communicate with all the ECUs in a Prius and thus can not read all the trouble codes that are waiting to be read.
    Anytime a warning light is visible on the dash, there are trouble codes that have been triggered, and a Prius capable scan tool should be used to read all the codes, not just some of the codes.

    The Car Scanner ELM app, the Dr Prius app, and many other scan tool apps and dedicated scan tools can not communicate with all the systems in a Prius. Anytime that you are diagnosing a problem with a Prius, it is very important to read all the trouble codes, so a capable scan tool is imperative to get a complete understanding of all the problems that the Prius has.
     
    #11 Brian1954, Jan 31, 2025 at 12:33 AM
    Last edited: Jan 31, 2025 at 12:56 AM
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  12. LKasdorf

    LKasdorf Junior Member

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    Well, I feel like an idiot. The engine was basically out of oil- nothing on the dipstick. Once I put in oil, no more red triangle! My son neglected to keep it topped up. This car apparently has carboned up rings and burns a lot of oil- I sure would like to resolve that!

    I still have the other brake related codes. I need to find my minivci cable or buy another, or buy a dedicated scanner and figure this out.

    I wonder if it is safe to drive it with those error lights on (minus the red triangle)? The brakes feel perfect.
     
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  13. MAX2

    MAX2 Member

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    Are you talking about the same car from the first message?
     
  14. LKasdorf

    LKasdorf Junior Member

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    Yes- the same car. I made that original post yesterday. I wonder if driving with those brake related err lights is a bad idea.
     
  15. ChapmanF

    ChapmanF Senior Member

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  16. MAX2

    MAX2 Member

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    Yes. Driving with a faulty brake system is wrong. You will be a source of increased danger to yourself and other road users. Find out the cause of the malfunction, fix the problem and then you can drive.
     
  17. Brian1954

    Brian1954 Senior Member

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    So, you have two different PriusChat user names, and you are using both of them in the same thread? That makes things very difficult to follow.
     
  18. LKasdorf

    LKasdorf Junior Member

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    Sorry! I didn't realize I had two accounts here. I will remedy that!
     
  19. PriusCamper

    PriusCamper Senior Member

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    This is very common as a Prius gets older and needs oil added between oil changes. My understanding is it only happens when you're more than 2 quarts low, which can be hard on an engine that doesn't require much more than 4 quarts...