Toyota's Stuck Accelerator Problem: The Real Cause

Originally posted by thedarklingthrush
911 stinks, I was wondering if you could reconcile two parts of your post for me.

1.) The video which claims to recreate the sudden accelerator

2.) The snippet later claims "The effects of EMI have proven costly and impossible to duplicate since its discovery"

How did that scientist recreate something that its apparently impossible to recreate?

I think you are talking about two different things here...

[edit on 2-3-2010 by thedarklingthrush]

To me that means that they can do a direct short with equipment hooked up, but don't know what kind of signal is causing the short in the real world.

Exponent has so far been unable to induce, through electrical disturbances to the system, either unintended acceleration or behavior that might be a precursor to such an event, despite concerted efforts toward this goal," concludes the preliminary study which has been shared with lawmakers planning hearings on Toyota's safety record.

online.wsj.com...

And here's from a press conference Toyota held.

There's certainly - at the bottom of the page, you can see various antenna that are broadcasting, cellular TV, radio antennas, as well as your typical noise sources, such as power lines and electrostatic discharge. That's just from the humans themselves operating the equipment in the vehicle.

From our test standards, we develop our performance target. These are both done at a design and a test strategy. As you can see from the slide, the component level and the vehicle level from a design perspective need to meet or exceed the international standard.

pressroom.toyota.com...

Probably can't find the signal that causes the problem because it is a top secret military type of signal.

Originally posted by kinda kurious
I am grateful for this thread. My elderly Mother-In-Law has a Camry and despite having the mod done is still scared to drive it. Her car is 2 years old and has less than 5,000 miles on it. She cannot financially afford to simply dump the car at a loss, so her family is all kicking in to get her another car and absorb the loss on the value she will lose. $$$


[edit on 2-3-2010 by kinda kurious]

I sure get tired of these rich car maker suggesting it's driver error, floormats, or sticky equipment on brand new vehicles.

Give me a break.

Glad you appreciate the thread.

Not sure about the video. Interesting find though. Hmm.

Anyone know of a place to grab a hold of the schematics for the accelerator circuit? I would love to analyze it...

Not for pass-time sake, but for professional sake of course

[edit on 2-3-2010 by ownbestenemy]

Originally posted by Pilgrum
Nice post.

I'm not clear on what the design engineers have done here because all the recent model cars I've worked on have a physical mechanical cable (non-electric) connecting the accelerator pedal to the air flow control on the manifold so there's no way it can open (the air-flow control) without human input by depressing the pedal.

What manufacturer's vehicles are you working on, most new vehicles in my shop have a pedal that has sensor outputs to the ECM. I don't see many vehicles with throttle cables anymore, hell Ford diesel trucks haven't had cables for nearly a decade if not more.

The important part though is that the Powertrain/engine control module does not rely only on the accelerator pedal position sensor. These modern drive by wire vehicles have what are known as fault management strategies. They use several signals from several sensors to self check the signals it is receiving and prevent issues These strategies are there to prevent things like uncontrolled acceleration, by cross-checking the data it is receiving against redundant sensors and other inputs. For example the Ford 7.3L diesel engines use three signals to indicate accelerator pedal position and relies on other inputs from the engine as well. Simply put, if these signals don't agree or are out of spec then the engine will derate power and only run at idle.

This isn't to say that there are issues with the Toyota design, programming or fault management strategies, but it's far more complicated and far safer than most people who don't work on them would understand. I don't work on many toyotas as I'm on the heavy duty side of things and can't speak to the actual issues with them but it isn't as simple as most think. It's not like there's a wire straight from the gas pedal to the fuel injectors, there is a lot more to it. Within that system there are numerous self-checks and safety measures.

Originally posted by ownbestenemy
Anyone know of a place to grab a hold of the schematics for the accelerator circuit? I would love to analyze it...

Not for pass-time sake, but for professional sake of course

[edit on 2-3-2010 by ownbestenemy]

Page 45 of the following pdf
energycommerce.house.gov...

Originally posted by DeepBlueSeas


The important part though is that the Powertrain/engine control module does not rely only on the accelerator pedal position sensor. These modern drive by wire vehicles have what are known as fault management strategies. They use several signals from several sensors to self check the signals it is receiving and prevent issues These strategies are there to prevent things like uncontrolled acceleration, by cross-checking the data it is receiving against redundant sensors and other inputs. For example the Ford 7.3L diesel engines use three signals to indicate accelerator pedal position and relies on other inputs from the engine as well. Simply put, if these signals don't agree or are out of spec then the engine will derate power and only run at idle.

This isn't to say that there are issues with the Toyota design, programming or fault management strategies, but it's far more complicated and far safer than most people who don't work on them would understand. I don't work on many toyotas as I'm on the heavy duty side of things and can't speak to the actual issues with them but it isn't as simple as most think. It's not like there's a wire straight from the gas pedal to the fuel injectors, there is a lot more to it. Within that system there are numerous self-checks and safety measures.

Thanks for your input.

All it takes is a signal on the wire that controls the butterfly motor, or injector flow valve. All the other inputs are in the logic chain, and are managed by a brain box. It doesn't matter what the other input signals are, if the final signal is calling for acceleration.

All the safety inputs come down to one wire, that controls throttle position.

I've worked on AC fly by wire systems in the military. There are redundant systems, but it all comes down to what the actuator is told to do.

I have seen Electrical interference first hand.
I had a VW that would shut down every-time a local sheriffs car would transmit within about 100 feet.
I ended up replacing the ignition brain to fix the problem.

The funny part was i sold to old unit to a cop that needed one for his car.

reply to post by pedroroach


Because they save money on components, wear and tear, fuel economy, and usually provide better safety.

People didn't have problems with steam trains, either, but we moved on from them once better technology presented itself. Luddism isn't helping anyone.

reply to post by 911stinks

Thanks for that but the breakout box is test equipment, not the schematics. Still yields information though

I doubt though one could find the schematics for Toyota's accelerator assembly as they probably are considered proprietary.

Originally posted by ownbestenemy
reply to post by 911stinks

 

Thanks for that but the breakout box is test equipment, not the schematics. Still yields information though

I doubt though one could find the schematics for Toyota's accelerator assembly as they probably are considered proprietary.

Yes, I apologize for that. What was interesting to me are the inputs. +5v, M+, M-, VTA1 and VTA2.

Must be a stepper motor.

I agree that accelerator assy is proprietary, but if I were having problems, I would post schematics publicly so that all could make their own judgement.

No doubt this problem could be caused by an electrical fault but I highly doubt it has anything to do with EMI. EMI can interfere with sensor outputs but filters are used extensively to fix this. Secondly, for a transistor to switch there needs to be .7 V over certain terminals. I can't imagine that typical EMI can induce such a voltage within a microcontroller and if this were possible all digital electronics WOULDN'T WORK!

To the person looking for a conspiracy in the switching from analog to digital TV/radio signals. Digital signals are able to be received and interpreted so much clearer than analog it's not funny.

the dumbass was talkin on the phone for like 4 mins to 911 before crashing...poor guy didnt even have time to put it in neutral and turn the key off

reply to post by metalholic


I am unsure if that was a silly attempt to make yourself look smart or just callous and cold.

While in hind-sight we all have ideas and thoughts about what we would do if we were in that situation, we fail to understand all the other factors that are happening.

1. Expectations are shattered, i.e. your car is not decelerating when it should

2. Adrenaline begins to start pumping through your body

3. Fight/Flight response begins to kick in and since there isn't much retreating from a speeding automobile, you begin to fight.

4. As you begin to fight, many new factors are thrown in: Fear, panic, desperation.

All of these are just words and cannot compare to what that person was actually experiencing in that moment. So I implore you to think for a second before you attempt that brain-typing connection you seem to take so halfheartedly.

reply to post by ownbestenemy


anyone who knows anything about a car and or driving if your breaks aint workin put it in neutral that will stop the drive train between the transmission and motor hence no more acceleration turn the key off and that cuts everything out unless his motor has to run for his brakes and or emergency brake to work he doesnt need his motor on any longer especially if his car is malfunctioning!

There is nothing wrong with Toyota, it is always excellent in performance. The US wants to bring down Japan because General Motor gone kaput!!

we all know about it it is pure evil conspiracy

reply to post by metalholic


Objectively yes, you may be correct. Subjectively you cannot say what you will or will not do during that situation. Also, it was not you, so you are suggesting if everyone were to have your wisdom and knowledge then they would have known what to do.

Its like telling a person that just lost a child that you know how they feel without yourself actually experiencing the situation yourself.

In theory vs. application, theory always looks better, but the very fact that it is not applied to a real world situation one can never know how the cards will fall so to speak.

reply to post by ownbestenemy


4 mins talking on the phone tells me everything! i used to work 7 days a week 12 hrs a day on 3rd shift about 30 mins from home i know all about panic situations! i've woke up driven down the interstate within seconds of running underneath the trailer of a semi or ass ending someone with the only choice of standing on the brake and turning into the fast lane without looking and almost crashing into concrete barrier so i think i know exactly what iw ould do in that situation with 4 mins to talk to 911...i've been in plenty of wrecks where i didnt wreck...i think i know what i'm talkin about!

so dont question or state that in a wreck i cant speculate on what I would do...the real thing here is he dont know how to drive or save his own ass in a wreck and neither did the authorities as they didnt even tell him to put it in neutral and turn the key off...with mins before crashing had he went to neutral he'd still be alive!

reply to post by metalholic


And I drive a total of 20 mins a day. Your situation is unique to many others. The pompous view that you have taken has shown nothing other than you have a superiority complex and instead of engaging the OP you attacked the person who panicked and failed to make sound choices all because they didn't have your state of mind.

Maybe a better analogy is needed.

Someone engaged daily in combat has a better chance at facing down a bank robber as opposed to the bank teller. Your experiences make you and your abilities. They do not make that other person and you have no idea what that person was feeling, thinking or doing during that 4 mins.

reply to post by ownbestenemy


Quite right.

Everyone is different and people's responses to unexpected crises varies greatly. Some will make good split-second decisions and others won't, some will simply panic or freeze and be unable to do anything to help themselves or anyone else. Maybe this thread will prompt a few to do a 'what-if' analysis of their own and get to know their vehicles a bit beyond simply steering so they'll have an idea of what's likely to work and what to do if it happens to them (let's hope it doesn't).

What's a worry here is that new vehicles are exhibiting these serious faults so what will those vehicles be like in 10 years or so when electrical connectors are getting a little loose and suffering the inevitable corrosion problems.

What's being reported is that putting the car in neutral, attempting to turn the engine off, etc., have not done anything to stop the car. Apparently it is like the driver loses all inputs but steering and brakes, and the brakes are insufficient to overcome a constant full throttle.