Help Diagnosing Unintended/Uncommanded Acceleration Issue

oh please tideland... is that why i have a package 9?.. because they only made 6 packages?....

did you forget they re did everything at the beginning of 06? seriously?

 

No big deal.

You said that the 04 and 05 had 9 packages.

Tideland only corrected that to say that the 05 had 6 packages.

According to the 2005 eBrochure, Tideland was right:

http://www.toyotacertified.com/ebrochures/05_prius.pdf

But yes, the 04 had 9 packages according to the 2004 eBrochure:

http://www.toyotacertified.com/ebrochures/04_prius.pdf

 

Then why is it described as package #8 (see third line) in the 2006 eBrochure which I've re-excerpted below?

"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
Discharge (HID) headlamps and integrated fog
lamps, JBL® AM/FM 6-disc In-dash CD changer w/9
speakers in seven locations, aux. audio jack,
MP3/WMA playback capability and hands-free phone
capability via Bluetooth® [7] wireless technology,
Voice-activated DVD navigation system[8], Leathertrimmed
seats and steering wheel. (NW)"

Compare how the 2006 eBrochure describes the following as package #6 (see third line):

"Option Combo H $3,830.00

50-State Emissions (FE)

Package #6 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 with HomeLink® [6]
universal transceiver, Smart Key System, backup
camera [4], Vehicle Stability Control (VSC) [5], High
Intensity Discharge (HID) headlamps and integrated
fog lamps, and JBL® AM/FM 6-disc In-dash CD
changer w/9 speakers in seven locations, aux. audio
jack, MP3/WMA playback capability and hands-free
phone capability via Bluetooth® [7] wireless
technology. (HK)"

Maybe there were changes during the model year of packaging numbers?

 

Hello all:

For what it's worth, here's an experience that I had with a rental car a few months back:

First off, I don't even remember what model/make it was, as I rent cars for work almost weekly. All I remember was that it was not a Prius.

I was leaving Boston Logan airport late at night, traveling westbound on the Mass Pike. I usually drive on the highway with the cruise control activated, and such was the case on this night. At one point, I stepped lightly on the brake to slow the car and cancel the cruise control.....and the car jumped forward instead, suddenly accelerating! As I was rounding a bend at this point (leading up to a toll plaza), and the road also dipped somewhat, I thought that it was my imagination.

But then it happened again, and again. It was actually quite startling, as the car would jump forward instead of slowing down, just as if I had stepped on the accelerator, instead of stepping on the brake.

I eventually figured out that whatever switch on the brake pedal is used to deactivate the cruise control was not working until I really stomped on the brake. Only then would the cruise deactivate. A light press on the brake would slow the speed just enough to make the cruise control think that it needed to apply the accelerator. Strangely enough, this would produce a vigorous acceleration as the car tried to compensate.

Needless to say, I notified the rental agency as soon as I returned the vehicle.

Maybe the problem with the OP's Prius has something to do with a malfunction in the ECU responsible for the cruise control, or possibly with an intermittent pedal pressure or position sensor switch problem?

Just wondering out loud....

 

Very interesting to actually see two-way communication going on with this issue. The only reports we've seen is a single post, and no responses to our questions. Well, I'm out of suggestions at the moment, seeing that shifting into neutral doesn't seem to be an option. I suppose that leaves pushing the park (and hoping it shifts into neutral) or the power button to force an emergency shutdown of all systems. I hope we can try and figure out exactly what is causing the problem, and the best way to take action to safely resolve the problem IF we encounter it too.

 

The (2004-2009) Prius detects the driver's pedal activity as follows:

Accelerator: detected solely by Hall-effect (magnetic field) sensors.

Brake: pressure applied detected using hydraulic pressure sensors. Speed of application measured by potentiometer.

I'd recommend keeping sources of electromagnetic fields well away from the accelerator pedal. Put a purse containing a mobile phone, or smart key, behind your seat, not in the footwell. I don't have any proof that it causes a problem, but I wouldn't take a risk on it.

In all cases there are multiple sensors which should track the same behaviour. In the accelerator there are two Hall-effect sensors, one of which produces a higher voltage than the other (nearly constant offset). In the brake, there are two pressure sensors, one in each of the two pipes leading from the master cylinder. The stroke sensor pot has two tracks, which again are correlated. If the correlation on any sensor goes out of range or values don't change when the corresponding sensor changed, a DTC is logged and the Master Warning Light is illuminated (at least for the accelerator pedal sensors; the Brake Control section doesn't say but I would expect one of the brake-system warning lights to stay on).

Your problem sounds like a badly-adjusted brake light switch. It should be set up to close when the pedal is pressed only a fraction. The Prius manual (I realise this wasn't a Prius) says 0.5 to 2.4mm. The Cruise Control version of the brake light switch has two poles, which act opposite to each other, used to self-check the switch's operation. The Prius does also use the brake light switch to cancel cruise control, rather than the HV ECU getting a message from the Skid Control ECU - one would think that the Skid Control's 'please regen' message would cancel as well, but it does need to still work even if Skid Control has packed up.

 

Please do a common sense check and get up close with a bright light and look a the mechanisms, springs, switches, electrical connections, and everything else that can be looked at closely. All it would take would be something that does not let the accelerator return to it's default position.

If its not the mat, then it maybe something doing the same thing as a caught mat would do.

 

Hi NYLion,

Your probably right. But just in case, take the driver's mat out and put it in the trunk for a month, and see what happens.

 

I second that. You may know it's not the mat, but when you go to the dealer or Toyota and they ask for specifics, having no mat really accelerates getting to the next level of questions.

 

While I did (and still do) question the veracity of this post, that in no way constitutes a personal attack. I referred to the post as one possibly from a “troll” which is not a personally derogatory statement about a person (like calling them stupid is), but a characterization of the poster as “one who posts a deliberately provocative message to a newsgroup or message board with the intention of causing maximum disruption and argument” (Urban Dictionary: troll). I was wondering if the person who posted this really was nylion (a long standing member) and if the purpose of the post might be primarily an attempt to add an unsupported negative accusation about the Prius to yet another website as further “evidence” of the supposed widespread nature of the “problem” rather than an attempt to seek help with a actual problem.

If, as you say, the person posting as user “nylion” was merely trying to figure out why their car is acting that way, then why use the inflammatory phrase: “My Prius tried to kill me,” as the title? Not only are such words, in my view, clearly intended to present the issue in an extremely unfavorable light (not to mention an anthropomorphic fallacy), but the words are also a commonly used catch phrase at other web sites. If you do a Google search on the phrase you will see that the exact phrase has been used in several other places including the recent article I mentioned and that the phrase has its origins in places like livejournal.com and consumeraffairs.com.

Much like the "known" low speed brake failure problem, this complaint about unintended acceleration (using that exact phrase as well as “Prius tried to kill me”) suggests the OP might (maybe, possibly, etc.) be associated with the cunsumeraffairs.com website (#1 Google search result for “Prius unintended acceleration”) the group who’s own connection to injury law firms is completely documented by them on their site https://www.consumeraffairs.com/php/a_report.php. So yes, the use of such catch phrases in the title and other unsupported accusatory claims like “Toyota has denied the problem” make me suspicious about the post. My statements regarding such suspicions do not constitute a personal attack. I simply stated, and do so again, that I am suspicious about the motives of the OP and veracity of the post. I did not refer to any PriusChat members as “lesser lights” as did the OP. That seems like a personal attack.

If you are including me in your apology, please don’t as I don’t apologize for being suspicious about the post. There was certainly nothing “venomous” about my words. If this post had come from a new registrant, many here would have been even more suspicious of the post. Given the nature of the board and the fact that unused user accounts are allowed to languish here indefinitely, I think my hack suspicion is quite reasonable. Indeed of the over 48,000 registered accounts here at PriusChat, almost half (approx. 24,000) have been members for more than 2 years but most all of them (approx 20,000) have not even logged in for the last two years. Of the 24,000 who have just signed up in the last two years, over 14,000 of those have never posted to the board. I would imagine, if I were so inclined, that I could find many an older user id here where the password is either identical to the user name (or only a slight variant there of) and could easily hack into one of them at any time. I’m not so inclined and I have a fixed IP as I’m always happy to have all I do and write online traced back to me. There are certainly ways you and the other moderators could check more carefully that the post from user id nylion, was from the original registrant and that the account is not a hack of one of the many dead user ids (as shown by the counts above) beyond the simple previous post check that we both did. You did not indicate if you checked any deeper. I believe that leaving so many old and unused registrations active on the site is an open invitation for just such hacking, and I also suspect (here I go again) the reason for leaving them accessible is equally transparent.

To nylion: If you are who you say, and you are really having the problem you describe with your Prius after having ruled out floor mats or other gas peddle obstructions, I strongly recommend you stop driving the car immediately. I too am genuinely concerned about your safety, that of your passengers, and others on the road. Driving a car you believe to be unsafe does strike me as negligent (funny that does sound like a phrase a lawyer would use) as well. You should have it towed to the dealer immediately and have every ECU replaced at your own expense if necessary. If this has happened three or more times, then it will likely happen again, perhaps at an even less opportune time. Others here, being the more trusting sort of folk than I, have offered some excellent suggestions to help you narrow down the many possible Toyota liable causes.

 

Everyone is concentrating on the pedal, mats, ECU, but if I had this problem, I would look at the throttle body. On the NHW11, a common problem with "no start" can be caused by a gummed up throttle body; it seems plausible to me that a sticky throttle body could cause an "unintended acceleration" scenario.