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P3024 code and a painted over check engine light

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PeterPeterPumpkinEater, Aug 4, 2019.

  1. PeterPeterPumpkinEater

    Joined:
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    Vehicle:
    2007 Prius
    Model:
    N/A
    Thanks everyone for the great info here. I’m in a bit of a pickle. I’ve had this 2007 Prius for almost 3 years; it now has 180,000 miles. I paid $3000 for it with a salvage title. When I took it to a mechanic to get the 12v battery replaced they let me know that someone had painted over the check engine light. This created a bit of a problem when I went to get the car smogged (California), but I had my 1 yr old son with me and he was having a tantrum and I guess they felt sorry for me and let me pass. Now I have another year before the next smog check and my son is better behaved and I’m not sure if I’ll get so lucky.

    On top of all that I started getting hybrid battery codes about 8 months ago. I’ve continued to drive the car, just clearing the codes as I go and it’s doing ok. I got a code reader and torque pro app, and most of the codes are P3024, worse when it’s hot outside, and rarely a P0A8 code.

    I wonder if I could get your thoughts. I have some DIY skills but I haven’t gotten into the battery yet, or tried to uncover the painted up check engine light. I feel I’ve gotten good use out of the car, but wonder how much longer I can keep driving it. I’ve thought about getting a new battery, then putting it into another Prius when it’s time for this one to be smogged again. Would that new battery be compatible with a gen 3 Prius? Is my 2007 Prius worth anything at this point? Thanks!
     
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    Vehicle:
    2007 Prius
    Model:
    Touring
    A Gen 2 battery will not physically mount or connect to a Gen 3 vehicle. The cases and electronics are totally different.

    P3024 is Block 14 becomes weak. That means Block 14 (the 2 modules closest to the ecu in the battery) has one (or two) modules failing. If this started 8 months ago, I'm impressed. The last battery I worked on that was reset over and over again for months actually had burned a hole through the side of a module by the time the owner had it replaced.

    As with most things in life, the worth of a vehicle is up to the owner. Although a salvage vehicle, if the condition is good, 180k miles is nothing to be scared of.

    Did the smog check people tell you what codes were present?
     
  3. PeterPeterPumpkinEater

    Joined:
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    Location:
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    Vehicle:
    2007 Prius
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    Thanks for your reply. There were actually no codes when I smogged it, and it passed emissions, but apparently if a light has been tampered with, they’re not supposed to pass it. The process of getting into the dash to undo the paint over is a little daunting to me.

    If I’m consistently getting that same battery code, is it a safe bet to only replace those 2 modules? And I’m trying to make sense of the ‘balancing’ thing as some people seem to be saying it’s fine just to put in the new modules and it balances itself.
     
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    2007 Prius
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    Touring
    Peter,

    Your HV battery has 28 individual modules inside. When your battery was brand new, you could think of it as having 28 "D" cell batteries inside. Just like people handle aging differently, as time passes and miles accumulate, each individual module also handles it differently. After 180k miles, instead of having 28 "D" cells, you now have 7 "D" cells, 7 "C" cells, 7 "AA" cells and 5 "AAA" cells and 2 "AAAA" batteries.

    Obviously, the D cells have the most capacity and the AAAA have the least capacity.

    The problem is that those AAAA batteries deplete much faster and their voltage drops much more quickly than the D and C cells. That voltage difference is what triggers the "xx block become weak" module fault codes.

    When we speak of balancing, the goal is to cycle the modules deeply enough to try to return the chemistry back to "D" cell condition. It's much more likely to end up with Some Ds, and some Cs.

    Not everyone has the ability or equipment to do this. In those cases, most try to perform some type of load test on each module to determine which ones are the obvious AAAA and AAA modules. If you can replace those, then the battery should at least last 6 months to a year (or even more) before the next C degrades to a AAA or AAAA.

    If not able to do a load test, then the only option is to replace the ones that are obviously bad and just roll on with your fingers crossed. I HAVE seen this done on a Gen 2 battery and it lasted over a year before I lost track of the battery.

    So the answer to your first question is: Although replacing those 2 modules (with no other testing performed) is not the ideal solution, it CAN work. You just don't know when or which module will fail next. It could be a week or it could be a year or more. Along with that, it's usually easy to identify which of the 2 modules is the troublemaker once you're able check them individually.
     
    Skibob likes this.