Tag Archives: Traffic Hazards

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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Shameful Behavior Award Given to Florida Department of Transportation: Red Light Cameras with Reduced Yellow Light Time

A hortrafficlightrible government action has just been reported on in Florida by 10 News

“TAMPA BAY, Florida — A subtle, but significant tweak to Florida’s rules regarding traffic signals has allowed local cities and counties to shorten yellow light intervals, resulting in millions of dollars in additional red light camera fines.

“The 10 News Investigators discovered the Florida Department of Transportation (FDOT) quietly changed the state’s policy on yellow intervals in 2011, reducing the minimum below federal recommendations. The rule change was followed by engineers, both from FDOT and local municipalities, collaborating to shorten the length of yellow lights at key intersections, specifically those with red light cameras (RLCs).”

The above yellow light “tweak” may result in significant extra fines, but it will undoubtedly result in many more accidents and injuries, some probably fatal. Yellow light timing should be based on a reasonable time for drivers to react to a yellow light and safely bring their vehicles to a halt before the light turns red. If yellow lights are shortened below reaction time, and drivers are fearful of possible fines, stomping of brakes and resultant rear-end collisions can be confidently predicted, as has already occurred in some areas where red-light cameras have been installed.

This shameful practice should be abolished immediately. Government officials should be first and foremost concerned with ensuring public safety, not increasing revenue through deceptive practices. Anyone getting a camera-based “red light” violation should challenge this despicable practice, and hopefully we will soon see some government officials jailed for the crime of public endangerment.

-Ed Walker


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

Engineering Thinking Extra Is A Short Review Of A Current Hot Topic

According to Reuters today (8 Feb 2011), “A government probe cleared Toyota Motor Corp’s electronics of causing unintended acceleration, a big victory for the world’s top automaker as it seeks to recover from the hit it took over runaway vehicle accidents.”

This news release is misleading. The investigation did not “clear” the electronics. Rather, the investigation could not find any evidence for the electronics being the source of the problem. Failure to find a cause is not the same as proving there was not a cause.

The following statement from the Los Angeles Times is more accurate:

“A NASA report on Toyota’s sudden acceleration found ‘no electronic flaws … capable of producing the large throttle openings required to create dangerous high-speed, unintended acceleration incidents.'”

Note that the NASA engineers used more careful language, indicating that they were not able to identify an electronics cause, not “proving” there was no cause.

Although I certainly respect engineers in general, there are aspects of this case that — at least until I have had a chance to review the NASA report — will not allow this particular engineer to agree that the case is closed.

In particular, although “stepping on the gas instead of the brake” is likely a factor in some cases, those cases are generally when moving from a  coasting mode to a quick stop.  (My aunt died in such an instance, when coming to a stop next to a grocery store wall.) In some reported cases, however, the driver is cruising along on the highway when the car suddenly starts accelerating, without the driver moving their foot. In at least one such case, the acceleration was terminated by switching off cruise control.

Also, as reported earlier, Toyota emails indicated that staff members celebrated their efforts to delay safety regulations and investigations (“ET EXTRA: Protecting Your Life: Toyota Joins The Gallery Of Shame“). This does not lead one to believe that Toyota Engineering was primarily concerned with finding the root cause of the issue. This type of behavior also raises serious doubts, including: were the vehicles studied by NASA representative of the failed vehicles, or did Toyota provide test vehicles wherein Toyota had already identified and corrected a root cause, such as an intermittent cruise control linkage?

If I have the opportunity to review the NASA report I will comment further. If anyone who worked on the report would like to comment, please do.

-Ed Walker


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ET EXTRA: Unintended Consequences

Engineering Thinking Extra Is A Short Review Of A Current Hot Topic

An essential Engineering Thinking principle is thoroughness. This involves not only checking the details, but also exploring nooks and crannies to be sure that all the details were indeed checked. The best engineers will do this, plus will stand back and look at the big picture to try to spot unintended consequences; particularly when dealing with critical safety issues.

There is nothing more disheartening than thinking you’ve done a great job, only to find out later that you missed a subtle but important flaw, and you’ve made things worse instead of better. Despite our best efforts, this does on occasion happen to all of us, sooner or later.

A recent example of unintended consequences is the switch to efficient LED lighting to replace older incandescent bulbs used in traffic lights. Municipalities have found out to their chagrin during the recent snowy weather that LED lights do not emit enough heat to melt off any snow that may cover them up, resulting in traffic hazards and expensive manual maintenance to keep the lights uncovered. By contrast, the older inefficient incandescent lights gave off enough heat to melt any snow, so “snowy weather maintenance” was not required.

(Ref. “LED Traffic Lights Don’t Melt Snow,” by Mark Frauenfelder)

-Ed Walker


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