1. Dsmrik

    Dsmrik New Member

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    Jun 26, 2020
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    Location:
    BC, Canada
    Vehicle:
    2007 Prius
    Model:
    Base
    Good day everyone!
    My 2007 Prius has 320,000kms. The hybrid battery does fluctuate wildly, often starts very low when parked for a day or 2. But the torque app says all cells are within .1 volt.
    So one day in town, 30ish mph, a loud beep, alarm comes on constantly, the red emergency brake light, yellow brake light, ABS, and Trac ctrl light all come on. My brake pedal is hard at top of travel. When I push the pedal, it feels like no brake boost and no front brakes. My back brakes locked up when slowing down. After stopping on roadside, I shut car off, then restarted. Alarm now off, all lights off. Car drives as usual. I hook up my torque app and no codes. I didn't clear anything.
    The local shop who works on the taxis couldn't get any codes either. He thought it was the anti theft shutting down the hybrid system thinking the car was stolen. But he was puzzled when I reminded him it doesn't have keyless. It hasn't happened again in 200 to 300 kms.
    The ABS pump does run with clicking sound, and barks occasionally when parked with my foot on the brake. But hasn't changed in the 1.5 years I've owned it.
    Should I take it to the dealer? Will their computer read history and info that the taxi shops snap on or other mechanics computer cant?
    I'm afraid to let my wife drive it. Suggestions?

    Thank you all for your time.
     
  2. Moses Bruh

    Moses Bruh Member

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    Location:
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    Vehicle:
    2008 Prius
    Model:
    Four
    Assuming the local shop used Techstream and had no codes, safest way would to have Toyota thoroughly inspect Brake System while giving them all the relevant information you have about the experience you had.
    1.how is your 12v Battery condition? I had a similar brake system issue (just driving straight on the freeway, with light pressure on brakes) one time, and that changing a new 12v battery it never happened again, however i did have the same brake system issue pop up a year later taking a turn, which may have been the combination of a bad abs actuator/ low engine oil.
    2. How is your engine oil level? I have seen posts where oil level between the low and high mark can still trigger issues with the engine on turns.
    Of course safest way is still having toyota dealer/ shop that is experienced with prius check the brake system, however at a cost.
     
    #2 Moses Bruh, Jun 27, 2020
    Last edited: Jun 27, 2020
  3. Dsmrik

    Dsmrik New Member

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    2007 Prius
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    Base
    Thx Moses!
    My 12v battery reads 11.9 with no load on display check.
    I think the taxi tech had techstream on a tablet... I can check. So if he does, then a Toyota dealer won't find any history either?
    Engine oil is 1/3 to 1/2 between the marks.
    Thank you again!
     
  4. davecook89t

    davecook89t Senior Member

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    Vehicle:
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    Four Touring
    Intermittent problems are always hard for the dealer to diagnose. They would be willing to try to chase down what is causing your issues, but it will cost you. My guess would be that you have a problem with an electrical connection somewhere. If you do not see any evidence of damage to your wiring from rodents etc., my next recommendation would be to pull out each fuse and relay (especially those in the fuse-box under the hood), one at a time, and check for corrosion or other deposits on each of their prongs. On a couple of occasions, the dashboard on our Gen 2 lit up (I believe I may also have heard a long beep as you describe), and to follow up on one of the suggestions I saw in this forum, I started pulling the fuses and found one with significant deposits on it. I cleaned it up and have not had that kind of issue since (fingers crossed).
     
  5. Dsmrik

    Dsmrik New Member

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    Base
    Thx Dave and Moses. I'll check these things.
     
  6. George W

    George W Active Member

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    Location:
    San Antonio
    Vehicle:
    2008 Prius
    Model:
    Touring

    11.9V is too low for your 12V battery (cold). Maybe take your battery to local auto parts place and ask them to load-test , and to charge it up.
     
  7. Dsmrik

    Dsmrik New Member

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    Location:
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    Vehicle:
    2007 Prius
    Model:
    Base
    So I went to taxi mechanic again this morning.

    He opened up the fuse box underhood, it looked clean and dry and he checked many fuses and relays with his tester.
    He checked some fuses under the dash as well and he found no concerns.
    I also got him to check the 12v battery with his tester: 12.2v no load (short drive from home to shop), 10.8v with load. He says those numbers aren't perfect but shouldn't require replacing the 12v battery or cause the problem.
    He says the alarm/no brake event is a "false theft alarm" shutting down the hybrid system, to prevent theft.
    Finally, his computer/software is "SnapOn" brand, $21,000 price tag he says, (not Techstream).

    What say you? Is Snap on ineffective with Prii? should I find a shop with Techstream? Or hit the Toyota stealership? Or is the 12v battery definitely due for replacement based on your experience with those test results?

    Thanks again for your patient assistance!
     
  8. George W

    George W Active Member

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    Location:
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    12.2V is still low for a cold measurement. A healthy charge from auto parts place wouldn't hurt.
     
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  9. davecook89t

    davecook89t Senior Member

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    Vehicle:
    2017 Prius
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    Four Touring
    I'm not sure about Snap On's ability to read Prius codes, I would guess it is not able to, given that none are being reported for your car. (It is hard to believe that a shop that services taxis in BC, where 95% of the fleet are Prii, does not use Techstream.) It is also my belief that Torque Pro cannot query the Skid Control ECU, which would be needed to get codes from the braking system. If you plan to keep a Prius for any length of time, and especially if you would like to save money and DIY for many repairs, I would recommend that you avail yourself of a mini VCI cable and Techstream (available through many vendors on Amazon). Since that may take awhile, in the meantime you would be best served by pulling blink codes from the Skid Control ECU using the method described here and reporting them back to us.
     
  10. dolj

    dolj Senior Member

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    Not really, there are other scanners just as capable as long as the right amount of money is spent on it. A shop that services multi-brands will find the investment in a multi-brand tool better value when compared to buying several brand-specific scanners or computer/software combos, so I doubt their tool, is not capable, given as you said, "95% of the fleet are Prii."
     
  11. Dsmrik

    Dsmrik New Member

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    Location:
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    Vehicle:
    2007 Prius
    Model:
    Base
    Sorry for the delay in updating.
    On July 6, I took my car to a hybrid specialist that uses Techstream. Got a loaner car of a Prius V, nice bonus to try out.
    Anyhow, their results are:


    Technician unable to confirm compliant. ABS has a C1242 Low voltage code which is fairly common on weak 12v batteries. Typically that code would not set driving done the road but it might just be a glitch as its very common to see that code and have no brake compliants. 12V battery was tested and is operating fine. Brake fluid level was checked and vehicle went on several road tests. Technician is wondering was the ABS light went on when it was hard to stop or did the dash so no signs of fault. Typically these issues are associated with ABS codes. ABS and related components are all currently operating as designed.
    Recommendation: Monitor concern and report back if fault occurs again


    Any last Words? The alarm/no brake boost hasn't repeated. The engine pings often under load up hills. So I'll just drive it until a major component fails.

    Thanks everyone!
     
  12. Moses Bruh

    Moses Bruh Member

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    If you ever have the problem again, check and note your engine oil level, and if your in a safe situation, note everything that happened on a paper or phone before you forget some details.
     
  13. Dsmrik

    Dsmrik New Member

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    Location:
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    Vehicle:
    2007 Prius
    Model:
    Base
    Noted for the future. Phone pic and video of sound, if there's a next time.
     
  14. Mendel Leisk

    Mendel Leisk Denizen of the LZ

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    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I'm a little sceptical of your latest test place. The 12.2 volt measurement you got before is very low. As mentioned up the page, get an electronic load-test done. Places like Canadian Tire have them (at least one in North Van when I was getting a battery for our son). They also have a Motomaster compatible AGM battery. Phone ahead, verify stock and that they can do load-test, clear up this variable. If for example the Cold Cranking Amps is below spec, coupled with the significantly low voltage reading, it's time.

    FWIW, a good condition AGM battery for the Prius should be reading 12.7~12.8 volts and CCA well above spec (which is something like 325).

    If you want to DIY test, something like Solar BA9 is a good entry level tester.

    That's a LOT of kms btw, getting to where if it's not one thing it's another territory?
     
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