Please Help - 08 ABS VSC Warning - Brakes Giving Out

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by jbumps wvu mntrs, Mar 4, 2011.

  1. jbumps wvu mntrs

    jbumps wvu mntrs PC Superfan

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    2010 Prius
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    III
    On my commute to work this morning my dash lit up wth warning lights for the ABS and VSC, shortly after I noticed that the brakes were pulsating.

    I was in slow traffic becuase of a wreck on the interstate and each time you touched the pedal enough to apply more than regenerative breaking, they would pulsate to the point of shaking the car (at under 7 miles an hour). The car acted as if the system was alternating between applying stopping force and not, several times per second.

    My scan gauge, much to my surprise, registered no codes, yet the dash looked like the starship enterprise. I'm going to go back out and try to get the gauge to toss a code or two my way, but without them I have no idea where to start. Does anyone have any ideas for either a cause/solution or a way to coax a code from the car?

    Thank you in advance to anyone who is able to offer help. This forum has been the greatest source of knowledge on this car and many other issues!
     
    #1 jbumps wvu mntrs, Mar 4, 2011
  2. jdenenberg

    jdenenberg EE Professor

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    My Subaru ABS went out causing the brake pedal to go to the floor when one of the ABS sensors was damaged due to a failed wheel bearing. Check the wheel rotation speed sensors. I assume that all your tires are the same size.

    JeffD
     
    #2 jdenenberg, Mar 4, 2011
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    You should not be surprised since any DTC would be logged by the skid control ECU. I do not think that generic devices like ScanGauge will be able to read them.

    Jeff offered a reasonable suggestion. If you don't notice a problem with the wheel rotation sensors or the associated wiring then I would encourage you to immediately take your car to your local Toyota dealer so that the DTC can be read and a diagnosis provided to you. Good luck.
     
    #3 Patrick Wong, Mar 4, 2011
  4. seilerts

    seilerts Battery Curmudgeon

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    Please clarify, are you discussing a 2008, or a 2010 as listed in your profile? If 2008, is it still under warranty (3/36 or extended)?

    ABS/VSC codes are different. They start with C rather than P. A ScanGauge expert could say whether or not it is possible to view those codes, otherwise you need a code reader. There is also a way to jumper the DLC terminal (where you plug in your SG) to get the computer to flash the codes, see http://priuschat.com/forums/gen-ii-...oting/60001-my-vsc-light-wont-turn-off-3.html

    Usually, ABS/VSC problems happen when 12V power to sensors runs low. This can be due to DC converter shutdown, causing the 12V battery to run low, or high resistance at a relay in the various ABS/VSC circuits. Usually, there is a DTC with the DC converter shutdown, such as P0A93 for inverter cooling pump failure. If you can rule out a 12V battery issue, then it is more likely to be a relay.
     
    #4 seilerts, Mar 4, 2011
  5. jbumps wvu mntrs

    jbumps wvu mntrs PC Superfan

    Joined:
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    Vehicle:
    2010 Prius
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    III
    Thank you to those who offered advice. It was our 08 that had trouble - we have a 2010 too. I did decide to take it up to the dealer we bought it from - only 10 miles from work. The irony of the whole situation that I didn't provide earlier needs to be explained now.

    I've owned the car since Februrary of 2008 and have over 100,000 miles on it. The only maintenance I've done is oil changes, tires, transmission fluid changes and new plugs a couple of weeks ago as part of BobWilson's recommended 100,000 mile "check-up". I put for sale signs in the car yesterday and then have this issue this morning. Prior to taking it up to the dealer from work this morning, I took the signs out of the back windows. 200ft out of the work parking lot - all warning lights disappear and the car is as good as new. I'm beginning to think that it doesn't want us to sell it.

    The dealer was able to pull two codes that they said the scangauge wouldn't be able to pick up. One was for a sudden drop in pressure and the other a lack of pressure in the accumulator. The lights came on shortly after I had to lock up the breaks to avoid being involved in an accident on the way to work. The tech did think that the car should have been able to acclimate itself quicker than the nearly 20 minutes and three start-ups/shut downs later, but nonetheless it seems to be fine.

    Thanks again for everyone's input and hopefully a few people that didn't know before, will now know that the Scan gauge doesn't have much luck picking up diagnostics related to ABS or VSC.
     
    #5 jbumps wvu mntrs, Mar 4, 2011
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