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Traction Batt shows 8 bars, bad mileage, no help from Toyota

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by szabi, Nov 3, 2010.

  1. szabi

    szabi I also have a 2007 Prius

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    The problem presents on a 2007 Prius with 27K mi on the clock. We have another one, a 2008 with 32K miles.

    At highway speeds, 55 to 70 mph, on flat highway (Interstate 5), the traction battery display shows completely green, 8 bars, 100% of the time, and the ICE runs and races too hard. Under the same conditions, the fuel mileage is poor, 39 mpg (indicated) continuously. No headwind, no crosswind, air temp = 70F. Tires 42psi front 40psi rear. There has been no sign of traction battery overheating, that is, the battery cooling fan has never come on. The brakes are not dragging.

    At low speeds, 25-35 mph, mileage and power response are normal, compared with the 2008 Prius.

    I suspect that these are symptoms of traction battery failure.

    The 12V battery shows normal measured with a DMM, 12.4 volts with no load and the system OFF, 14.4 volts while charging. I disconnected the 12V battery for 1 hour, no changes.

    My Toyota dealer (Chuck Patterson in Chico CA) says, in short, no DTCs, no problem. They will not do any warranty work unless there are problems that throw a DTC.


    Help, please.
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I agree that it appears that your 2007 has a problem, but I would be more inclined to think that the hybrid vehicle ECU or the traction battery ECU are at fault - for charging the traction battery more than it needs to be.

    It is understandable that your dealer's service dept is not going to take any action if there are no warning lights and no DTC. That is a normal service dept response. They don't want to spend their tech's time chasing a problem with no obvious cause and little likelihood that they'll be reimbursed by Toyota for that effort. (If you offer to pay for that diagnostic time, maybe they'll be more receptive towards looking into the issue.)

    I suppose that you'll have to keep driving the 2007 until more obvious signs of a problem appear. I suggest that you try to log a greater proportion of miles on that vehicle, since it seems to be lightly used compared to your other Prius. Good luck.
     
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  3. Bob64

    Bob64 Sapphire of the Blue Sky

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    Do you have a scangauge? If so, try programming in the amps xgauge (to monitor current flow in/out of the battery) and the RPM of the engine...

    Perhaps that can give you some insight as to whats going on...
     
  4. adric22

    adric22 Ev and Hybrid Enthusiast

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    Read this article I wrote on hybrid repairs, and maybe it'll help you better understand what goes on in a dealership service dept:

    Ridiculously Expensive Hybrid Repairs! | evtalk
     
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  5. krg03

    krg03 Not expert, just experienced

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    I had almost this same problem. My ECU was not charging the traction battery properly at higher speeds. Unfortunately the dealership didn't believe the scanguage so it wasn't a help. While it gave me peace of mind to the problem, I had to pay for the diagnostic (which they only tested at lower speeds so I had to argue further) and wait/argue with toyota for rebursement on a warranty issue that was clearly documented by the dealership and work done under warranty. It took hounding the district service manager to get my diagnostic money back.
     
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  6. szabi

    szabi I also have a 2007 Prius

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    How was the problem finally resolved? Thanks for your help.
     
  7. krg03

    krg03 Not expert, just experienced

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    I paid for the diagnostics. They found the ECU "marginal" so they replaced it. That fixed the problem perfectly. I have another 07 so it was easy to compare ideas/problems of how its suppose to work. It was only then they started really looking into it as a problem.
    They of course tested it and at first found nothing. Until they ran the car at higher speeds (at my request....again), they then found it "somewhat" faulty. They said I would have to contact toyota to get a refund for my diagnostic fee. I did which a month later never saw anything. I contacted the district manager which looked at the records, claimed he disciplined the service manager (right) and the same dealership issued a refund check. Got some free car wash and oil change coupons. All in all a very big hassle but it got fixed for free. I have all the time in the world of course.
    Yours still could be the traction battery as Patrick Wong said and the dealership is kind of like the idot lights. Could be something else too. Unless something is really wrong and really broken it's hard to get them to do anything without an error code.
    It will take them time and your constant annoying voice to get them to actually trouble-shoot by replacing something just for grins.
     
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  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Actually, I am inclined to think the OP's problem is an ECU. Can you please refer to your repair invoice and provide the part number and description of the ECU that was replaced? Thanks.
     
  9. szabi

    szabi I also have a 2007 Prius

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  10. jdenenberg

    jdenenberg EE Professor

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  11. szabi

    szabi I also have a 2007 Prius

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  12. vertex

    vertex Active Member

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    Go back to the dealer. Get the service manager into the car, and take him on the highway to see the problem first hand. If he won't, call the district manager and complain. The fact that you have 2 Prii, should give your story more credability. The problem is the ECU thinks the battery is over charged, and tries to discharge it by running the ICE, killing your mileage.
     
  13. szabi

    szabi I also have a 2007 Prius

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    UPDATE:

    The problem now appears to be fixed. I rebooted the ECUs, that is, disconnected the 12V battery for 1 hr. When the system came up again, the original problem remained, however, after 1 day and 10 miles, I found normal or better-than-normal fuel mileage and a normal battery charge, 6 bars.

    Either the reboot cured it, or faith healing or ?? Thanks for advice from all. If the problem recurs, I will re-post.
     
  14. caffeinekid

    caffeinekid Duct Tape Extraordinaire

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    That is a great writeup. :cool:

    Speaking as a technician in another industry entirely, suffice it to say that it is NOT just automobiles either. In fact, if automobiles are anything like what I work on, the idiot lights and various trouble codes are almost NEVER precise.....which can get damned expensive for a customer...or not, depending on whether you go with a manufacturer franchise or an independent. And technicians in general are either poorly paid for the most part, or not paid at a level commensurate with the cost of the required education.


    As for the OP's vehicle, I think mentioning the reset-reboot procedure as a sticky-type standard troubleshooting step would be helpful....unless its already been done and I just missed it. :(