Category Archives: Root Cause

ET ALERT: Toyota ‘Unintended Acceleration’ Is Still Occurring


Despite claims that Toyota’s problems with unintended acceleration have been due to driver error, or cured via floor-mat adjustments, a recent case has been reported wherein neither of those factors were relevant. As reported by “Charles” in a message to Engineering Thinking:

The following events occurred on May 15, 2015 while driving from Charleston, SC to Nashville, TN (I-26, I-40) in my 2012 Toyota Highlander.  Normally interstate traffic is so congested it prevents use of cruise control; however, that morning I was able to turn it on and set it on 75 MPH.  As we were coming up on slower moving traffic, I applied the brakes to switch off the cruise control and it did not work – even after pumping the brake pedal.  I then used the off/on on button(switch) on end of cruise control lever to switch off cruise control – and that worked. If that switch had failed – or if I had panicked – then I would have had a “runaway” Toyota.  The car did not accelerate, but when you are standing on the brakes and the car is still “cruising” at 75 MPH it sure feels like it is accelerating.

Later on during the same trip I tried the cruise control again (several times actually) and each time applying the brakes would not switch off the cruise control.  Whatever is wrong with the cruise control system, on this Toyota, it is what we call in my line of work a “solid fault” – not intermittent.  I feel confident that my car will repeat the scenario every time it is tried…

…I am a semi-retired Electrical Engineer with over 40 years in the power industry.  For approximately 5 of those 40+ years I worked as a field engineer, testing and commissioning power control systems.  So I know a little something about how control systems (cruise or otherwise) are supposed to function.  I would like to add, that in my testing/commissioning experience, I only had one programmable relay that failed out-of-the-box, and it was not a software problem.  All the problems I encountered were related to wiring and/or wiring design … I strongly suspect the Toyota “problem” may also be related to wiring (wiring harness, assembly process, etc) not software.

…Please note, our Highlander has the factory floor mats which are held in place by two hooks.  My cruise control issue had (has) nothing to do with floor mats….


Charles’ expert qualifications and detailed report are compelling evidence that Toyota still has a serious issue that cannot be dismissed by blaming the driver or the floor mats. My thanks to Charles for sharing his experience, and for alerting Toyota owners to the fact that ‘unintended acceleration’ is still a very real possibility.

Prior posts on this issue can be found at the following links:

Toyota Unintended Acceleration: “No Electronics-Based Cause”: Not True & Misleading

Customers Claim “Fixed” Toyotas Are Still Accelerating

Toyota’s “Drive By Wire” Throttle System Suspected As Crash Cause

Stop Driving Recalled Toyotas

Toyota Unintended Acceleration Causing Deaths And Injuries

-Ed Walker


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Autism and Other Neurodevelopmental Disabilities: Are We Poisoning Our Future?

brainscan“…many more chemicals than the known dozen or so identified as neurotoxicants contribute to a “silent pandemic” of neurobehavioral deficits that is eroding intelligence, disrupting behaviors, and damaging societies.”

from “Growing number of chemicals linked with brain disorders in children,” 14 Feb 2014, Harvard School of Public Health,


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Castor Oil Instead Of Ritalin? Might Be Worth A Try

angrychildBad behavior has been strongly linked to bad diet:

“‘When we look at fish consumption across countries, those countries that have the highest fish consumption have 30 fold lower homicide rates,’ said Hibbeln.”

(from “Hearing: violence epidemic linked to bad diet” by Mark Davis, 7 Nov 2013,

There are likely other reasons, such as genetic factors and a culture that condones senseless violence in television, movies, and video games, but the strong linkage reported above implies that some behavioral problems might be mitigated by dietary corrections. (Note: Always check with your doctor before starting/stopping/switching any prescription drug.)

Here’s another good summary of ways to tune up your diet:

13 Nutrition Lies That Made The World Sick And Fat
by Kris Gunnars, 16 Oct 2013 Business Insider

-Ed Walker


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Vaccinations, Autism, Psychics, and Silver Bullets

To solve complex problems, engineers try to identify all of the important variables that might be in play. Working from this list, each variable is analyzed and tested to determine its effect, if any, on the problem, until the root cause of the problem is identified. The root cause is often traced to a dominant variable, a Big Gorilla. Sometimes, however, it’s not possible to clearly identify a root cause, either because an important variable was not on the list, or because the cause is a combination of variables, and that combination was not considered.

Because we are prone to thinking there is always a single silver-bullet solution to every problem (see “The Single-Event Fallacy (Am I Psychic?)” in this post: “I’m Right! (Or Am I?)“), the possibility of a problem being caused by a combination of significant variables is often disregarded, making problem-solving efforts ineffective and even misleading. For example, a scientific study of thimerosal (50% mercury) in vaccinations may conclude that there is no correlation to autism, and the media will then shout, “Vaccinations don’t cause autism!” But this conclusion is not scientifically justified. For example, is there something else in vaccinations — either by itself or in combination with other factors, including thimerosal — that is linked to autism?

Therefore, in addition to all of the standard skeptical questions one should ask about any study (e.g., was there a control group? were statistics used properly? was the study funded by an organization that has a stake in the results?), it’s always good to be cautious about accepting overly broad conclusions from a study where only a single variable was considered.

Regarding autism and vaccinations, researchers have recently identified a correlation between the Haemophilus influenzae type b (Hib) vaccine and autism (“Hypothesis: Conjugate vaccines may predispose children to autism spectrum disorders,” discussed here). Hib can now be added to the list of possible significant variables (see “Off Topic: The Autism Epidemic) that may play a significant role in the perplexing and devastating puzzle of autism.

-Ed Walker


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The Government’s Policies And Our Economic Crisis (Part 1)

An important engineering principle is empirical validation, or proving that something is correct by test and measurement. Theories are great, but a theory isn’t worth two cents if it doesn’t match the real world.

Let’s see how the principle of empirical validation affects an engineering team’s deliberations, as they investigate the root cause of economic downturns.

Charlie (team leader): The purpose of today’s meeting is to review the results of our research on the causes of economic meltdowns in the United States. Nigel, we’ll start with you.

Nigel: In reviewing over a dozen recessions and depressions in the U.S. economy that occurred during the last hundred years, I found that most of them were normal business cycles that lasted about one year on average. The Great Depression that started in 1929 was an exception, because it persisted for several years.

Charlie: Why was the Great Depression so much longer than the other downturns?

Nigel: By doing a sensitivity analysis of major variables, I found that the length of the downturns was strongly correlated with the degree of governmental involvement in the economy. For example, a severe depression occurred in 1920 during which the government did very little, yet the depression only lasted about eighteen months. By comparison, the government intervened massively during the ten years of the Great Depression.

Charlie: Okay, but we all know that correlation is not proof of causation; maybe the government was coincidentally involved when the economy got worse. Any other thoughts? Marcy?

Marcy: Based on Nigel’s results I searched for a prototypical experiment that would support or refute his hypothesis. Fortunately, such an experiment was conducted over several decades wherein massive governmental control of an economy was performed. The experiment was carried out by the Soviet Union during the years 1922 to 1991.

Charlie: Good; there’s nothing better than empirical evidence. And the results?

Marcy: Economic performance was persistently poor. One could easily conclude that the experiment was a striking failure.

Charlie: Could the failure be explained by some variables other than the government’s involvement?

Marcy: In my view, no. The Soviet citizens were of high intelligence, and despite the single-minded — even brutal —  management of the economy by the government, the results were dismal. In fact, considering the intensity and duration of the experiment, had it been a success the Soviet Union today would likely be the world’s dominant economic superpower.

Sam: Some economists today are saying the opposite of what Nigel and Marcy report. They’re saying that the Great Depression lasted so long because the government didn’t intervene enough; that the government should have spent even more money than it did.

Charlie: Do those economists have any empirical data to support their claims?

Sam: Um, well, they cite the fact that the depression ended following World War Two, during which the government spent a lot more money.

Charlie: A correlation, yes, but not necessarily a cause. How do they explain all of the instances where the government did little, and yet, as Nigel found, the economy quickly recovered? How do they explain the fact that the economy worsened when government spending was massively increased prior to the world war? How do they discount the very convincing experiment performed by the Soviet Union? It seems that their theory does not match the empirical evidence.

Sam: Um, well, I guess I don’t have the answer to that.

Charlie: Okay, if those economists have no empirical data to back up their theory, then we should discount it. It appears then that the best hypothesis for the root cause of extended economic meltdowns is governmental interference. All agreed? Good; meeting adjourned.

Next Post:

A Trip To The Government Store

-Ed Walker


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Cause or Coincidence?

Humans appear to be wired, for survival reasons, to jump to conclusions based on personal experience, particularly regarding potential threats. Eons ago, Harry eat red berries and Harry fall down, have convulsions, and die. Conclusion: We no eat red berries. Can’t argue with that. Although other varieties of red berries may provide wonderful nourishment, why take a chance?

Equating consumption of red berries with dying is an example of a correlation; an observed apparent coupling of one thing to another. As statisticians like to say, however, correlation is not proof of causation. The classic example of this is the observation that the rooster crows at dawn, i.e. there is a correlation between the rooster crowing and the sun peeping over the horizon. A primitive person might observe this correlation and conclude that the rooster’s crowing causes the sun to come up. Actually, as we know, the reverse is true; i.e. the rooster’s crowing is a result, not a cause. Therefore, to learn the correct lessons from observing correlations, it’s important to discern cause from effect.

In other instances, a correlation is simply a coincidence; i.e. no true correlation exists. For example, someone dreams that a loved one will be in an accident, and subsequently they are. Although the dream is observed to correlate with the subsequent unfortunate event, in truth this was just a coincidence (see “The Single Event Fallacy” in “I’m Right! (Or Am I?)”). But the person who had such a dream will (unless they employ Engineering Thinking) understandably be very likely to conclude that they’ve experienced a profound psychic event.

If an engineering design exhibits problems, engineers are very careful to thoroughly examine the situation. They can’t afford to confuse cause and effect, or to assume that correlations exist when they may not. Instead, they study and test until they have a reasonable certainty that they truly understand the root cause of the problem. This understanding allows engineers to devise effective solutions.

A misguided attempt to fix a problem, without understanding the true root cause, can make things worse instead of better. An even more unfortunate result is when a fix superficially appears to work, wherein in reality it introduces hidden defects. Later in time — after the supposed fixers have taken their bows and are long gone from the scene — the hidden defects erupt, wreaking havoc. Because of the time delay, the defects may not be perceived as having originated with the earlier faulty fix. This is indeed a tragic outcome: a supposed solution is perceived as being successful, when in reality it made things worse.

An Action’s Success Should Not Be Judged
On Whether Or Not It Appears To Improve Things In The Short Run,
Instead It Should Be Judged On Whether Or Not
(A) The Improvement Is Maintained Over Time, And
(B) The Improvement Is Superior To Alternative Actions (Including Doing Nothing)

For example, the conventional wisdom is that during the Great Depression president Franklin D. Roosevelt helped guide the economy to recovery by vigorously inserting the federal government into economic affairs. FDR initiated a myriad of intrusions, such as “work relief” programs; jobs that were funded by the government. Eventually — many years later, during World War 2 — the economy finally did indeed improve. Some observers thought, wow, FDR didn’t spend enough federal money, because it wasn’t until the world war started and federal spending went up even more, that we finally got ourselves out of the depression. In other words, there was a perceived correlation between massive federal spending and the end of the depression. But was this correlation properly interpreted? Was federal spending the root cause of the recovery?

In our next post we’ll take a look at how an engineering team might address that question.

Next Post:

A Brief Engineering Review of Economic Meltdowns

-Ed Walker


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