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Unintended acelleration + hill assist acelleration

Discussion in 'Gen 3 Prius Technical Discussion' started by tomconter, Jul 24, 2010.

  1. tomconter

    tomconter New Member

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    I just got our 2010 Prius back from the dealer after a 2-week safety review. Here are the incident reports in my wife's words:

    June 29, 2010     : After stopping at the library which is located in a shopping center, I drove slowly through the parking lot and approached a T intersection which did not have a stop sign. With the car at a complete stop at that T intersection, another vehicle crossed in front of our Prius. As I released the brake, and without depressing the accelerator, the car surged ahead and struck the other vehicle in the side.

    July 9, 2010:     I was at a full stop at the stoplight at Rockrimmon & Delmonico at 7:15 this morning. I was the third car in the line at the light (which is a LONG light), and I have adopted the habit of leaving a lot of space between me and the car in front of me.

    I had my foot on the brake because it was a long stop. There was suddenly a beep and the orange “skidding†light came on the left edge of the dash panel [The hill assist light]. The car was not moving AT ALL – it was at a dead stop at the light. I didn’t know what to do to get that light off and figured I would get across the intersection after the light changed and stop at the gas station to see why the light had come one. The traffic light changed to green. I eased my foot off the brake – and the car leapt forward. I had not yet put my foot onto the gas pedal. When I DID put my foot on the gas, the car continued forward and the orange light went out. I continued driving and there were no other incidents.


    Toyota hired an independent safety analysis engineer who reviewed the car for 4 hours and declared it safe to drive. He also gave me a flash drive with info about the EDR, an Event Data Recorder. He did not find a relevant read-out from it. I also found this info about the EDR in Toyota's explanation of the device:


    What is an EDR? An Event Data Recorder records some types of crash events in the vehicles computers for later research or analysis. An event is a change in vehicle speed that is more than typical or everyday use. For example, stopping hard with the brakes
    would not cause a recording, but hitting a curb hard may.
    What causes the EDR to record? The EDR starts to record when the vehicle experiences a rapid change in speed (like acceleration or deceleration) that exceeds a specified threshold higher than normal use.

    Well no wonder they didn't find anything wrong.     Both events probably recorded like it was normal acceleration. I intend to sent this thread to the engineer and see if he responds. If he does I will post his answer.
     
    #1 tomconter, Jul 24, 2010
    1 person likes this.
  2. bisco

    bisco cookie crumbler

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    that's a bummer. maybe they should drive it for a few weeks?:confused:
     
    #2 bisco, Jul 24, 2010
  3. adamace1

    adamace1 Senior Member

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    On your first report, I'm sorry if that really happened to your wife. I just hope she isn't lieing to cover up her hitting the gas and thus hitting the other car. I'm not saying she did or that i know what happened. But most of the time the person lies to get out of the blame and Toyota is easy to blame with all the news lately.

    The second one i recomend reading the owners manual before drive the car. There is alot of usefull stuff in there. When you stop if you push down harder on the pedal the hill assist will come on. It will show the light and beep. Wha this does is keeps the brakes on long enuff for you to move your foot fron the brake pedal to the gas pedal with out the car rolling. Say your on a large hill, hill assist will keep your car from rolling backward into the car behind you during the time your foot goes from the brake to the gas pedal.

    If i let of my brake my car will move foward on it's own, just like any other car.


    I will give you a chance that this really happend. And want to make sure you know what to do in a bad situation.

    1. First you two need to know that you can put the prius in neutral at any time.
    HOLD THE SHIFTER IN THE N SPOT UNTILL IT SHIFTS INTO NEUTRAL may take 1-3 seconds.

    2. Make sure you know you can power down the car by pressing and holding the power button. You can do this at any time, but you will loose the power brakes and power steering, making the car harder to steer and stop, but can save your life in a runaway situation.

    3. Also on the 2010 prius the brake pedal will overide the gas pedal. tested this on my car i was going 50mph and i i pushed down halfway on the gas pedal, then hit the brakes, the car shut down the ICE ans slowed down even though i was still pushing down on the gas.


    My question for you? You say the car surged foward, Did the ICE start when this happened? Or was it the electric motors?
     
    #3 adamace1, Jul 24, 2010
  4. ksstathead

    ksstathead Active Member

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    The Leaping Prius!

    Wish you had a scangauge to read rpm during some leaps. The MGs have pretty good torque from a stop, but the ICE is normally off unless you give substantial throttle input.

    So if the ICE is suddenly going WOT and adding thrust, that would be a problem with the car. But the MGs alone only cause gentle acceleration when the brake is released, simulating a car with an automatic transmission. The scangauge would also (with x-gauges) report the amps being drawn and the rpm of the MGs and the ICE.

    Sounds to me like hill assist worked as designed. Can she reproduce the excessive acceleration?
     
    #4 ksstathead, Jul 24, 2010
  5. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    That is perfectly normal on a Prius. The car is designed to "creep forward" if the shift is in drive and neither the brake or accelerator is depressed. The brake must be pushed down to keep from creeping ahead.

    What does the driver's manual call the "hill assist light"? Look on pages 186 and 187 of the owners manual to find the correct name. Again the "leapt forward" is the "creep forward" designed into all Prius's. It's there to keep people from getting out to the car with the system on (but perfectly quiet) by moving once pressure is taken off the brake.
     
    #5 FL_Prius_Driver, Jul 24, 2010
  6. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Can you provide a Google map identification of the where this happened? I noticed the exit from Village Center is also on a somewhat steep, down grade.

    Was she driving South on Delmonico? The reason I ask is the Google Street view shows a sharp dip in the sidewalk.

    Regardless, this suggests we might try steep downgrades and see if it 'gravity' might provide the 'sudden acceleration' after the hill climb turns off.

    Bob Wilson
     
    #6 bwilson4web, Jul 24, 2010
  7. KK6PD

    KK6PD _ . _ . / _ _ . _

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    is that similar to.....

    Acceleration    :D:eek:
     
    #7 KK6PD, Jul 24, 2010
    2 people like this.
  8. bisco

    bisco cookie crumbler

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    hello? hello?:eek:hwell:
     
    #8 bisco, Jul 24, 2010
  9. adamace1

    adamace1 Senior Member

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    I think we may have another user error. :(
     
    #9 adamace1, Jul 24, 2010
  10. TheSpoils

    TheSpoils Member

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    The words surged, jumped, sped, took off should just be removed from comments referring to the Prius. It is just not possible.
    The other day my shopping cart took off and rammed into the side of another cart. Oh! I'm sorry my shopping cart surged and hit you. SOUNDS CRAZY.
     
    #10 TheSpoils, Jul 24, 2010
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