Help Diagnosing Unintended/Uncommanded Acceleration Issue

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by nylion, May 2, 2009.

  1. nylion

    nylion New Member

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    My 2006 Prius (pkg 8) has on several occasions decided to accelerate on its own. This always happens when the car is stopped. Lifting my foot from the brake causes the car to accelerate as fast as it can. Up until yesterday I wasn't totally sure my senses weren't lying. I had read a couple of articles where people complained of this problem. In the earlier cases, I was stoped at a flow control light on a freeway ramp, so the rapid acceleration wasn't a problem and when I stepped on the gas, it stopped.

    Yesterday I was on a surface street and stopped at a light. When I gently lifted my foot from the brake to start the car rolling, the car revved the ICE and acted as though I had floored the accelerator (my foot was still on the brake and I hadn't released full pressure yet. When I pushed hard on the brake, the car stoped and the ICE stopped reving, repeating gently easing up on the brake made the same thing happen again.

    Needless to say, I was getting concnerned. I tried shifting to neutral (no deal) and finally turned the cruise control on and then off (it was off). This stopped the acceleration. I have made a service appointment, but the dealer claims they never heard of this problem before.

    I did some research on the Web (search Prius unintended acceleration incidents) and discovered this has happened more than a few times for others. According to my reading, Toyota has denied the problem and claimed the floor mat was pressing on the gas. In my case, the first thing I did is check my mat (heavy rubber that never moves) and it was safely tucked under the pedals.

    If there is a fix for this, I haven't seen mention of it. I did report it to the NHTSA. I will report on the dealer's response. In the meantime be aware this has been happening on 2004 - 2008 cars. Some of the reports claim it is a cruise control issue. Who knows?

    I will be most interested to see how Toyota responds.
     
  2. F8L

    F8L Protecting Habitat & AG Lands

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    What were your internet sources if I may ask?
     
  3. Tideland Prius

    Tideland Prius Moderator of the North
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    Could you videotape it for us? You could also send that tape in to NHTSA
     
  4. galaxee

    galaxee mostly benevolent

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    the heavy rubber mat that never moves tends to migrate upward on the passenger side anytime someone is in the passenger seat in my car. do you have the mat hooks on the driver's side so that the driver's mat can't migrate up?
     
  5. Bob64

    Bob64 Sapphire of the Blue Sky

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    wait a sec?
    shifting into neutral and it STILL accelerated?
     
  6. flatline16

    flatline16 New Member

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    I have heard about this, but I cant remember what caused it. I saw an article on line.
     
  7. Tideland Prius

    Tideland Prius Moderator of the North
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    Good catch. The Prius can't rev its engine in neutral.
     
  8. FL_Prius_Driver

    FL_Prius_Driver Senior Member

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    I'm not sure Toyota can do much more than just take you report. It may be very advisable to get rid of the floor mat or hard secure it to the floor like the stock mats are. If it occurs with no floor mat, you have a much stronger case. All it takes for this to happen is for a small piece to hook the pedal. You don't fine out until you take you foot off the brake long after the hooking occured. When it happens, you are a LOT more preoccupied with solving the situation than sticking you head way down to look to see what might be catching the pedal.

    I would point out that this is very common, yet the claim is usually the electronics went haywire. As long as you have an unsecured, non-stock mat on the floor, you will have a hard time making a strong case.
     
  9. jpadc

    jpadc Type before I think too often

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    3 years no posts and now this just after a recent biased, not to mention reference free, article got printed many places...

    - Smells a lot like password hacking troll here...
     
  10. firepa63

    firepa63 Former Prius Owner

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    How did the OP buy a 2006 package 8? There is no 06 package 8 to my knowledge...
     
  11. V8Cobrakid

    V8Cobrakid Green Handyman

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    04 and 05 models were split up into 9 packages...
     
  12. Boo

    Boo Boola Boola Member

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    I think there is an 06 package 8. From the 2006 Prius eBrochure:

    http://www.toyotacertified.com/ebrochures/06_prius.pdf

    "Option Combo J $6,890.00

    50-State Emissions (FE)
    Package #8 Includes: Driver and front passenger
    front seat-mounted side airbags and front and rear
    side curtain airbags [3], Anti-theft system and autodimming
    rearview mirror w/HomeLink® [6] universal
    transceiver, Smart Key System, backup camera [4],
    Vehicle Stability Control (VSC) [5], High Intensity
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    seats and steering wheel. (NW)"
     
  13. DeadPhish

    DeadPhish Senior Member

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    You are in for a tough road methinks. No one here has ever experienced anything like that and I've been involved with nearly 1000 people that have them as well as driving one for 112,000 miles myself.

    The reaction that you received from the Toyota service dep't ( I'm giving you the benefit of the doubt that you are NOT a troll ) is likely what you will face all over the place. The only reports of such occurances are always 3rd party reports. No one actually knows any Prius owner who's had this experience. None are on film and the condition can never be replicated. BTW...the frequent reports of such occurances in a variety of vehicles from a variety of makers are almost always debunked and they never advance beyond the accusatory stage.

    Thus it appears very likely that these reports are at worst fabricated ( not to say yours is :D ) or at the least misunderstood.

    Your headline leads one to believe that you're looking for attention..the bad kind of attention.
     
  14. Tideland Prius

    Tideland Prius Moderator of the North
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    '05 had 6 packages
     
  15. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Historically, intermittent problems are the most difficult to diagnose but it sounds like your particular vehicle is repeating the failure symptom.

    Over what period of time and how frequently have these "flow control light" incidents occurred?

    What part of the country are you in?

    In the past, you wrote," ... when I stepped on the gas, it stopped." Did you try that this time too?

    We have seen random, isolated reports that seem to be unable to reproduce. Somehow, you've "got the touch."

    When you were stopped, was the engine still running? A warmed up Prius will stop the engine when the vehicle is stopped. So did the engine sit there idling or did it suddenly begin running?

    The reason I ask is there is a technique called "forced charging" where the brake is held with the accelerator is pressed. This keeps the engine running but as soon as the accelerator is let off, the engine stops.

    Regardless, let's look at the common elements:
    • shifting to neutral - handled by the hybrid vehicle ECU
    • accelerator signal - handled by the hybrid vehicle ECU
    • cruise control - handled by the hybrid vehicle ECU
    One interesting experiment someone with an NHW20 might try is to hold maximum accelerator and verify that you can shift into "N".

    Is that a Toyota floor mat? Any possibility of a photo of the mat?

    My NHW11 floor mats have carpet on one side over a rubber base. I have seen no reports of unexpected acceleration in the NHW11.

    I believe Toyota came out with a TIS that addressed the floor mat problem. Since I don't have an NHW20, I'm not sure of the number.
    I'm confused did Toyota ignore the problem by claiming the floor mat was pressing on the gas? This sounds like Toyota responded by identification of a problem with floor mats.

    If you can reproduce this problem, it will be easy to diagnose it. But once you take it to the dealer, will you ever trust what they've done has fixed the problem?

    You may be in a position to resolve the problem not only to your satisfaction but also share what is learned with this group and Toyota. Alternatively, you can let the local Toyota dealer try to find something wrong. Regardless, you have interesting choices.

    GOOD LUCK!
    Bob Wilson
     
  16. donee

    donee New Member

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    Hi NYLion,

    The heavy rubber matt that Toyota sold should not reach up far enough so that its under the pedals. It stops about 1 inch short of the pedal. This indicates that you have the mat installed wrong.

    So, it does not touch the pedal now, but after you have operated pedal, it will rotate down lower, and catch on the front lip of the mat. When you hit the brakes, that over-rides the gas pedal postion, and when you lift the brakes, the gas pedal position becomes the command to the car. And off it goes.

    The driver's matt has holes in it, and was supplyed with little J-hooks. You need to plug those hooks into the holes in the floor of the car, and the other end into the holes in the matt. And DO not drive the car with the matts if this is not done.
     
  17. richard schumacher

    richard schumacher shortbus driver

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    BZZT! Wrong answer. No mat should ever be anywhere near the gas pedal. Get it out of there. Replace it with a real Toyota mat that engages with the floor hooks near the seat mounting.
     
  18. hampdenwireless

    hampdenwireless Active Member

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    I don't think we should attack writers personally for writing potentially negative things about the Prius.

    While it probably is the floor mats, I don't think the OP is trying to 'attack' the Prius, they are trying to figure out why their car is acting the way it is.
     
  19. firepa63

    firepa63 Former Prius Owner

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    Nope ... that's a package 6. My brother-in-law has one.
     
  20. chogan2

    chogan2 Senior Member

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    The recent unintended acceleration Prius story (published in several free newspapers) was circulated at my church. I got motivated to download and summarize all of the National Highway Transportation Safety Administration safety complaints that deal with vehicle speed control, for the years 2004-2009 pooled (the gen II Prius years).

    I did not have a count of vehicles sold, so these are just the raw data. In terms of injuries reported, the Prius was 18th or so. This did not strike me as being hugely disproportionate to the Prius' share of cars sold over this period.

    No doubt you can have isolated incidents, but I don't think there's any likely common fault that the OP can appeal to, for an explanation of unintended acceleration. FWIW, the NHTSA did not open any inquiry on a possible manufacturing defect on the Prius for this.


    NHTSA Vehicle Safety Complaint Database
    Model Years 2004 - 2009
    Count of complaints and injuries related to vehicle speed control
    By make and model
    Top 100 vehicles by number of reported injuries
    Rank Make Model Complaints Injuries
    1TOYOTA CAMRY 247 41
    2LEXUS ES350 52 22
    3JEEP GRAND CHEROKEE 80 21
    4FORD ESCAPE 68 15
    5HONDA ACCORD 51 13
    6TOYOTA TACOMA 127 13
    7FORD F 150 64 11
    8MERCURY GRAND MARQUIS 43 9
    9FORD MUSTANG 69 8
    10HONDA CIVIC 44 8
    11JEEP LIBERTY 26 8
    12LEXUS ES 330 28 8
    13SUZUKI GSX R1000 11 8
    14TOYOTA COROLLA 34 7
    15FORD EXPLORER 65 6
    16HONDA CR V 9 6
    17LINCOLN TOWN CAR 40 6
    18TOYOTA PRIUS 42 6
    19TOYOTA SIENNA 52 6
    20CADILLAC CTS 11 5
    21ACURA MDX 4 4
    22BMW 328I 1 4
    23CHEVROLET MALIBU 11 4
    24FORD F150 39 4
    25CHEVROLET COBALT 18 3
    26DODGE DURANGO 44 3
    27FORD MUSTANG GT 12 3
    28JEEP COMMANDER 12 3
    29JEEP LIBERTY 4X4 11 3
    30LEXUS ES 12 3
    31LEXUS ES330 13 3
    32MAZDA TRIBUTE 33 3
    33MERCEDES BENZ CLS500 1 3
    34NISSAN ALTIMA 18 3
    35NISSAN MAXIMA 10 3
    36SUBARU FORESTER 19 3
    37TOYOTA MATRIX 6 3
    38TOYOTA SCION TC 3 3
    39BMW 325I 6 2
    40BMW X3 5 2
    41CHEVROLET COLORADO 22 2
    42CHRYSLER PACIFICA 22 2
    43CHRYSLER PT CRUISER 8 2
    44DODGE INTREPID 1 2
    45FORD F 450 SD 1 2
    46FORD FIVE HUNDRED 11 2
    47FORD FOCUS 27 2
    48FORD RANGER 17 2
    49GMC CANYON 6 2
    50HONDA PILOT 11 2
    51HYUNDAI ACCENT 2 2
    52HYUNDAI ELANTRA 11 2
    53HYUNDAI XG 350 7 2
    54INFINITI G35 SEDAN 9 2
    55LEXUS GS300 2 2
    56LEXUS LS 2 2
    57LEXUS RX350 2 2
    58LEXUS RX400H 7 2
    59MERCEDES BENZ ML350 3 2
    60MINI COOPER S 4 2
    61TOYOTA CAMRY SOLARA 17 2
    62TOYOTA HIGHLANDER HYBRID 1 2
    63YAMAHA YZFR6 3 2
    64ACURA TL 5 1
    65AUDI A4 10 1
    66BMW R 1200 RT 1 1
    67BUICK LUCERNE 10 1
    68BUICK RENDEZVOUS 6 1
    69CADILLAC SRX 11 1
    70CADILLAC STS 3 1
    71CHEVROLET AVEO 11 1
    72CHEVROLET SILVERADO 20 1
    73CHEVROLET TRAILBLAZER 32 1
    74CHRYSLER 300M 1 1
    75CHRYSLER SEBRING 19 1
    76DODGE 3500 1 1
    77DODGE NEON 6 1
    78DODGE RAM 1500 10 1
    79DODGE RAM 2500 8 1
    80FORD CROWN VICTORIA 10 1
    81FORD EDGE 1 1
    82FORD F250 SUPERDUTY 4 1
    83FORD FREESTAR 8 1
    84FORD FUSION 7 1
    85GMC ENVOY 10 1
    86HARLEY DAVIDSON FLHTCU 3 1
    87HONDA CIVIC HYBRID 2 1
    88HONDA RIDGELINE 3 1
    89HONDA S2000 1 1
    90HYOSUNG AQUILA 2 1
    91HYUNDAI SANTA FE 49 1
    92INDEPENDENCE FREEDOM EXPRESS 2 1
    93INFINITI M35 3 1
    94KENWORTH T800 1 1
    95KIA SEDONA 20 1
    96KIA SORENTO 5 1
    97KIA SPORTAGE 1 1
    98KYMCO AGILITY 1 1
    99LEXUS IS250 5 1
    100LEXUS LS430 2 1
     
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