Another head scratcher

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by David Mc, Aug 14, 2025 at 7:43 PM.

  1. David Mc

    David Mc Junior Member

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    I have the Triangle.

    The problem is the car system says both 12v (12.1) and hybrid (14) are ok.
    However the screen shows the batter not charging while driving then eventually kicking into limp mode.
    After getting home and shutting off and checking hybrid it still reads 13.9 to 14.1 restarting car allows me to drive again for a short distance and the screen shows it charging till it kick off again. Usually 4 miles or less.

    Is this the inverter failing or something else as I'm stumped.
     
    #1 David Mc, Aug 14, 2025 at 7:43 PM
  2. Brian1954

    Brian1954 Senior Member

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    Read the trouble codes using a capable scanner.
     
    #2 Brian1954, Aug 14, 2025 at 8:13 PM
    Last edited: Aug 14, 2025 at 8:22 PM
  3. ChapmanF

    ChapmanF Senior Member

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    ^ This.

    Because there are a couple hundred reasons that triangle can be on, it's generally premature to start asking "do I agree with what the car is saying?" before knowing which of 200 things the car is saying.
     
    #3 ChapmanF, Aug 14, 2025 at 8:18 PM
  4. bisco

    bisco cookie crumbler

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    where does the car tell you the hybrid battery is okay?
     
    #4 bisco, Aug 14, 2025 at 8:32 PM
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  5. Tombukt2

    Tombukt2 Senior Member

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    The 14 has nothing to do with the hybrid battery buddy
     
    #5 Tombukt2, Aug 14, 2025 at 8:55 PM
  6. bisco

    bisco cookie crumbler

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    what does it have to do with?
     
    #6 bisco, Aug 14, 2025 at 9:02 PM
  7. Tombukt2

    Tombukt2 Senior Member

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    It tells ya the DC to DC converter is producing the voltage to maintain 12V systems . Tells me nothing about the 200Volt DC HV system at all me no think . I mean because it's charging the 12V is not much
     
    #7 Tombukt2, Aug 14, 2025 at 9:08 PM
  8. David Mc

    David Mc Junior Member

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    When you do the car test the MFD gives you the numbers for both the 12v and the hybrid which is where I got my numbers from.

    The only scanner I have is a Harbor Freight OB2 iirc.
     
    #8 David Mc, Aug 15, 2025 at 12:39 AM
  9. T1 Terry

    T1 Terry Active Member

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    12v on a 12v lead acid battery, means all the capacity is gone and the battery is down to 50% SOC ..... 12v battery is in the process of passing over to the other side .....
    The 14v is probably the voltage at the 14v battery with the system on, meaning the DC to DC is applying 14v to the DC circuit.

    T1 Terry
     
    #9 T1 Terry, Aug 15, 2025 at 3:31 AM
  10. dolj

    dolj Senior Member

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    It does no such thing. I'm not sure where that idea has come from, but it is wrong.

    Probably came from AI. LOL.
    ^^^ This. ...
    ^^^ and this.
     
    #10 dolj, Aug 15, 2025 at 5:14 AM
  11. mr_guy_mann

    mr_guy_mann Senior Member

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    You need a more capable scantool to check the 15-16 systems on a Gen2 Prius. Here is a thread that reviews several options. The synopsis is post 37 (Autel AP200 is a good choice for general diagnostics).

    https://priuschat.com/index.php?posts/3246758

    Posted via the PriusChat mobile app.
     
    #11 mr_guy_mann, Aug 15, 2025 at 8:05 AM
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  12. ChapmanF

    ChapmanF Senior Member

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    Well, gen 2's MFD does have a "vehicle signal check" screen that will show you the 12-volt system voltage. It doesn't show traction battery voltage. (Its normal screens include the simplified traction battery bargraph, of course.)

    I've always found the MFD voltage display to be a good fraction of a volt lower than what I see on a meter at the battery, so if I saw something like 12 there it really wouldn't concern me at all.
     
    #12 ChapmanF, Aug 15, 2025 at 11:01 AM
  13. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Dash reported voltage of the 12 volt battery is not exactly a battery assessment. One of the electronic testers that assesses CCA and gives a verdict is the usual go-to. They have names like "Digital Battery Tester" and "Automotive Battery Analyzer". I've got an older model "Solar BA5", works.
     
    #13 Mendel Leisk, Aug 15, 2025 at 12:04 PM
  14. bisco

    bisco cookie crumbler

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    could be the inverter pump i spose, or maybe a battery module or two
     
    #14 bisco, Aug 15, 2025 at 1:36 PM
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