Toyota's Stuck Accelerator Problem: The Real Cause

Yesterday, Toyota had it's third hearing.

The National Highway Traffic Safety Administration is considering making brake-override systems mandatory for all cars going forward as a way of coping with the unintended acceleration, Transportation Secretary Ray LaHood said yesterday.

content.usatoday.com...

This to me says they are admitting an electronic problem, and it's not really fixable. The only solution is an override device cutting final power off to the throttle motor.

Here is a link to an AP video saying what I have been saying. Good video!

As Toyota blames poorly fitting floor mats and sticky gas pedals for the recall of millions of vehicles, the growing tangle of wires, sensors and computer chips are being scrutinized as the root cause…

news.yahoo.com...

About 18-20 years ago I know someone who had the cruise control stick on a Vauxhall Senator at 70 + MPH on the motorway/highway. He tried the switch and the foot break but it wouldn't slow down. Eventually he got it on to the hard shoulder and put it into Park. The car stopped alright and didn't do any damage to th gearbox or motor.

He's someone who is used to driving and must have kept his wits about him.

A Vauxhall/Opel Senator was about the size of a BMW 5 series or E class Mercedes, had a straight 6 3.0 litre engine and was built like a tank.

The build quality of motor manfacturers has deteriated in the last 10 years, they don't build stuff to last just at the lowest price they can. It's the same with TV's and washing machines, they have a shorter life span than they used to. It's not "if" they breakdown but "when".

reply to post by 911stinks


From an engineering standpoint, using a mass produced logic computer to stop a moving automobile is stupidity at it's finest. You, dear reader, are sitting in front of a computer a lot more sophisticated than the one in your car. Would you trust it to stop your car? Didn't think so. If you ask me, it would be a lot cheaper, and a world safer, if the accelerator was activated by a cable, like they used to be, and if the braking of the car was done manually, by pressing a pedal to push fluid to the wheel cylinders and calipers. I am aware that computers fly aircraft now, but a car, for all effects and purposes, is not an aircraft. Car manufacturers need to follow the KISS method.
Keep It Simple Stupid.

Originally posted by davesidious
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.

How is a cable more expensive than a position sensor and a stepper motor? How is it more fuel efficiency to turn human energy into an electrical signal to run a electric motor? The ECM of the car still controls the fuel delivery, not the throttle plate.
And its not Luddism, its a safety issue. How many times has your computer crashed last month?

reply to post by pedroroach


Don't compare a desktop computer to an embedded system - that is a very bad analogy. I studied embedded computers and real-time systems at university and appreciate the differences in hardware, software, and I/O. Embedded systems don't run flash, don't get attacked over the internet, don't download large emails while bittorrenting and playing MP3s. They run an extensively-audited piece of code, on a precisely-known set of hardware. Faults are not unknown, but they are far, far less common than on a desktop computer.

An accelerator cable is most likely cheaper than an electronic replacement, I agree. Not all old mechanical solutions in cars are cheaper, though, as mechanical linkages are usually very model-specific, whereas electronic devices are not. Model-specific parts are going to be more expensive than comparable parts that are usable in more than one model.

reply to post by davesidious


Embedded systems or not, one thing you have learned is that computers are not infallible.

Now we have seen what happens when a computer controlling a throttle plate does when it messes up, it is very unpredictable.

Now when a cable breaks, the throttle return spring will close the butterfly and you will slow down.

Mechanical controlling mechanical should be the norm in cars anyways.

[edit on 3-3-2010 by pedroroach]

[edit on 3-3-2010 by pedroroach]

Big hat tip to OP and many subsequent posters offering input to this vexing issue. As I mentioned, I have a keen interest in this subject.

As 911stinks said, the video illustrates the ability to induce a hard-wired short under test conditions, but not in real world.

As we all know, intermittent problems are hardest to solve. I am beginning to think in light of the AP video that this is part and parcel (and quite possibly the beginning) of the inherent risks of complex electronics and computers to perform mundane tasks.

Conspiracy and analysis aside, I still maintain that Toyota (is/has) handled this poorly. Inasmuch as it may bring about a fail-safe brake overide in future models, where does that leave the millions who are stuck with existing vehicles?

Once again, emotion and perceived sense of security is paramount to technical understanding for many drivers like my elderly Mother-In-Law.
However, with her limited understanding of such things, she suspects a simple little piece of metal won't solve this issue and provides no solace. And perhaps, your seat is not a flotation device.

I look forward to future updates and thanks again 911stinks for your diligence throught this thread. It offers me great insight in the most unlikely of placrs, right inder my nose.

EDIT TO ADD RELATED:

Accelerator Overide to Become Mandatory?

www.dailyfinance.com...


Regards...kk


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

Originally posted by pedroroach
reply to post by davesidious

 

Embedded systems or not, one thing you have learned is that computers are not infallible.

Now we have seen what happens when a computer controlling a throttle plate does when it messes up, it is very unpredictable.

Now when a cable breaks, the throttle return spring will close the butterfly and you will slow down.

Mechanical controlling mechanical should be the norm in cars anyways.

[edit on 3-3-2010 by pedroroach]

[edit on 3-3-2010 by pedroroach]

Just think about all the aircraft controlled by the same type of systems.

Things will get worse as more and more transient signals are broadcast.

I fear that this will affect our everyday lives much more than most are aware in the near future.

Anyone have a DVD player quit on them recently?

Originally posted by kinda kurious
Big hat tip to OP and many subsequent posters offering input to this vexing issue. As I mentioned, I have a keen interest in this subject.

As 911stinks said, the video illustrates the ability to induce a hard-wired short under test conditions, but not in real world.

As we all know, intermittent problems are hardest to solve. I am beginning to think in light of the AP video that this is part and parcel (and quite possibly the beginning) of the inherent risks of complex electronics and computers to perform mundane tasks.

Conspiracy and analysisaside, I still maintain that Toyota handled this poorly. Inasmuch as it may bring about a fail-safe brake overide in future models, where does that leave the millions who are stuck with existing vehicles.

Once again, emotion and perceived sense of security is paramount to technical understanding for many drivers like my elderly Mother-In-Law.
However, with her limited understanding of such things, she suspects a simple little piece of metal won't solve this issue and provides no solace. And perhaps, your seat is not a flotation device.

I look forward to future updates and thanks again 911stinks for your diligence throught this thread. It offers me great insight in the most unlikely of placrs, right inder my nose.

EDIT TO ADD RELATED:

www.dailyfinance.com...


Regards...kk

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

A great reply!

The problem is this whole thing will get swept under the rug, and life will go on as usual, except for a few class action law suits.

However, I believe the problem will get so bad soon enough that people will not be able to ignore it.

reply to post by 911stinks


Who knows. Perhaps it will stoke a demand in older cars?

In addition to my daily driver, I have an older German car.

Still has throttle cable and when I look under the hood, I know what every single wire / hose does.

EDIT TO ADD:

Perhaps a simple solution would be to always carry a capable passenger.
[atsimg]http://files.abovetopsecret.com/images/member/4aac3bc341bf.jpg[/atsimg]

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

Just to add this, PM came out with this article as we were having this discussion. I know that this single article doesn't solve the issues or concerns or prove anything about Toyota but it does cover what I've been saying in further depth and explains more about the system design in Toyotas. BTW, I agree that interference could cause the actuator and open the throttle (if EMI has an effect on vehicle systems) if though you have a redundant sensor that is outputting the actual position of the throttle body or the airflow, MAP, etc. then it will see that the signals aren't in agreement and cause a code/derate of power.

Oh, and to those who'd prefer mechanical linkages, what makes you think it's better because you can touch, feel and see it? Cables bind up, linkages bend or break, springs fatigue, all manner of issues can come up. To say that it is safer because it is mechanical is a farce, people just feel better if they can have it front of them and tangible.

Anyway, from PM Link:

Toyota has recalled millions of cars and trucks—4.2 million to replace floor mats that might impede throttle-pedal travel, and 2.4 million to install a shim behind the electronic pedal assembly. All of the affected pedal assemblies were made by Canadian supplier CTS. Toyota's boffins have documented a problem that can make a few of these pedals slow to return, and maybe even stick down. Problem solved.

But the media, Congress—and personal-injury lawyers—smell the blood in the water. Not to diminish the injuries and a few deaths attributable to these very real mechanical problems, but they're statistically only a very small blip, which may explain why Toyota took so long to identify the issue, especially when it has symptoms similar to the similarly documented floor mat recall. Plus, sudden unintended acceleration (SUA) is notoriously difficult to diagnose because, more often then not, the problem can't be repeated in front of a mechanic. Let's not forget the Audi SUA episode back in the '80s; the National Highway Traffic Safety Administration eventually concluded that there was no mechanical problem. The culprit, as hard as this is to admit, was most likely driver error. To put the issue into context, in the last decade, there were about 24,000 customer complaints about SUA involving almost every major automaker. The NHTSA investigated fewer than 50.

The issue now is whether there's a more insidious problem unrelated to the two recalls already extant. Specifically, whether there's some design flaw in the entire concept of electronic throttle control. Some are questioning whether electromagnetic interference from devices like cellphones could be contributing to the acceleration problems.

It used to be that there was a steel cable that ran from the pedal itself through the firewall and attached to the throttle blades that admitted air to the intake manifold. A sticking throttle could be the result of friction anywhere—in the pedal pivot, between the cable itself and its nylon-lined sheath, or in the carburetor or fuel-injection throttle blades. (Does anybody remember carburetors?). Modern cars, which make up the majority on the market today, use a throttle pedal assembly that is connected to the engine only electronically. Signals are carried over wires to the engine management computer, which in turn sends electrical impulses to the stepper motor that actually controls the throttle blades.

Sounds like there are plenty of places for gremlins to seize control of the works, right? And that's where pundits who don't really understand the architecture of throttle-by-wire systems go wrong. It's all in the engineering.
Continued>

reply to post by ownbestenemy


actually the first post was a sarcastic remark..secondly you tried to tell me that i dont know what i would do in a panic situation been in enough of them i know exactly what i would do...like is aid before THE REAL THING is he didnt know how to save his own ass and even more importantly THE AUTHORITIES didnt either...the problem aint my cold sense of humour its societies inability to help itself!

*************** UPDATE ********************

Some claim "fix" not working:

cosmos.bcst.yahoo.com...

Toyota’s “black box” information is now emerging as a critical legal issue amid the recall of 8 million vehicles by the world’s largest automaker.

The Company said that the devices record data from five seconds before until two seconds after an air bag is deployed in a crash, in an answer to AP when it asked Toyota to comment on what is stored in its recorders.

Toyota has also maintained that it shared EDR information with government regulators

whitehatfirm.com...

I believe Toyota shared the information. It's the government who doesn't want the truth to come out.

I currently work at an auto parts store (a fairly large chain) and I hear this sudden acceleration complaint quite a bit, and have experienced it once myself.

Modern vehicles use a sensor called a throttle position sensor. I'll tell you what happened to me.

I drive a Jeep Cherokee 4x4. 4.0L straight six. Awesome engine. I noticed that occasionally I'd start the truck and the rpm's would immediately tach to 3000. I'd tap the gas, and they'd stabilize to normal. Then I tripped a check engine code.

Throttle position sensor. Knowing Chrysler vehicles occasionally trip codes for absolutely no reason other than they feel like it, I just left it alone and watched it. Then the throttle started surging..in traffic. I changed the sensor and that fixed the problem, but I wasn't satisfied.

I googled "Cherokee accelerator issues" and I was astonished at what I found. Jeep Cherokees surged a bit, overthrottling on startup, same as what I was experiencing. Annoying, but nothing severe. Jeep Grand Cherokees, however...had been reported as putting the vehicle through people's living rooms, drive-thrus, etc.

Check engine lights are important. Autozone, Pep Boys, O'Reilly's, and Advance (just to name a few) offer check engine code readings free of charge. Take advantage of it.

[edit on 6-3-2010 by netwarrior]

Toyota knows more then they are letting out
tech.slashdot.org...
whitehatfirm.com...
www.foxnews.com...
onthehillblog.blogspot.com...

reply to post by DeepBlueSeas


You've opened my eyes somewhat as I wasn't aware of a trend toward 'fly-by-wire' engine controls which I have yet to encounter here on a domestic type vehicle (in Australia). What's a worry is these signs that the control system logic can 'lock out' the driver from having the last word IE unable to simply turn off the ignition or take the vehicle out of gear if what's being reported in relation to some of these run-aways is fact. Automotive technology hasn't reached the reliability level required to design the driver out of the equation just yet and the driver must be able to 'kill' or over-ride the system at all times without needing to read the manual first.

That being said, the hair-whitening experiences I've had in vehicles have all been in very conventional carburetor & cable type units with no computers or cruise control whatsoever. In all those incidents I was able to avoid catastrophe by simply turning off the ignition and shifting into neutral (I prefer manual transmissions) but I'll admit there was an element of luck in having sufficient space to take such action successfully on every occasion.

Did you see yesterdays news?

Sikes, whose 2008 Toyota Prius accelerated suddenly on a California interstate Monday, reaching 94 MPH before he was able to bring it under control with the help of the California Highway Patrol, said the cause of the incident was a "stuck" accelerator.

abcnews.go.com...

Maybe Toyota can get some answers from this one.

Well I always knew this would happen. When I was in school for this stuff they were just starting to talk about how everyone was going to switch to fly by wire throttle control and were also considering the same for steering the vehicle! HA!
One of the biggest problems I see in all the newer vehicles (OBD1/OBD2) is sensor malfunctions and electrical problems. When a sensor malfunctions it can stop working all together or can output false readings. Electrical issues can also cause a good sensor to give false readings. That's the first thing I thought when I was learning about fly by wire throttle is that what if the sensor in the pedal malfunctions and gives a false reading to the PCM (the vehicles computer)?
Say the sensor that detects pedal movement has an output of 1v(no pedal depression/idle) to 5v(WOT/wide open throttle) that the PCM monitors to determine where to position the throttle. Picture electricity going through a wire (source) that gradually restricts the flow of electricity more and more as the electricity goes farther down that wire. Now picture another wire feeding off of that one that moves from one end of it to the other. If the 2nd wire feeds off the source wire at the point where electricity flows unrestricted then the PCM senses a high voltage and tells the car go faster (I'm simplifying here). If the wire feeds off the other end of the source wire after the electricity has been restricted so as it flows at only a trickle then the PCM senses a low voltage and tells the car cut power and slow the engine.
If there was somehow a short in that sensor then would could happen is that while that 2nd wire was sitting at the low voltage side(idle/no pedal depression) of the source wire, somehow(there's lots of ways it could happen) the electricity could bypass the restriction in the source wire and go straight into the 2nd wire so that the PCM monitoring the voltage coming off that 2nd wire reads a high voltage as though it was sitting on the unrestricted(WOT) position of the source wire and tells your car GO FAST NOW! All without you even touching the pedal.
This is a possibility on just one kind of rheostat sensor a manufacturer could use to detect the position of the gas pedal. I'm sure there are other sensor designs they may use but regardless a similar situation could occur in those as well, I just used the easiest one to explain. Hopefully those of you reading that don't have experience with these sorts of thing understood my post because your who I wrote it for!
Anyways...I *think* that is exactly what the scientist lookin guy in the video is doing. He's shorting out a sensor the PCM uses to determine where to position the throttle and creating that false reading. I don't think hes shorting anything in the PCM itself because I think it would be a little more complicated then just making one microscopic transistor (one of thousands) inside the PCM to switch on or off to make it tell the car to go vroom. Also, the input and output wires to the PCM ARE shielded to prevent EM disruption in the circuit. Some times you can hear it in your cars speakers when the shielding is removed or when certain wires are ran through the vehicle in a way they weren't designed to be.
So I guess what I'm trying to say in this very long post is that I believe a sensor or electrical malfunction is more probable then something sparking in the PCM itself.

I hope to god these idiots never implement a fly by wire brake or steering system! I would NEVER drive that car especially after this mess!