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Unattended acceleration fact or fiction?

I was driving my 2006 F-150 up to a favorite camping spot last summer, pulling a 24 foot travel trailer. I am of normal height and weight and I’d like to think I possess at least normal or above normal intelligence. My shoe size is 11, not especially large, probably pretty close to normal for a man of my size. (that will come into play shortly) I’ve been driving now for 39 years and consider myself a pretty good driver, with only one accident in a blinding, whiteout snow storm outside Rapid City, S.D. 37 years ago. I have a BS in Automotive Technology, have worked on cars for a career or hobby the majority of the past 30 years. I’ve heard stories over the years about a vehicle experiencing unattended acceleration, especially with the recent settlement by Toyota Motor Company. There have been numerous news-type shows with stories about this over the past 10 years, and I’ve always looked at them with a bit of wonderment. I don’t doubt that some of them are legitimate. Others I have never been convinced are real. Now back to the camping story. I was driving through a small town between my house and our destination, and started slowing down for a stop sign. I was pulling the trailer, and had the trailer brakes set pretty aggressively, so as to save my truck brakes. Here is where the problem started, I could tell the truck was not slowing down like it should have been, while there was some slowing, there was also the feeling it was trying to speed up. The harder I pushed on the brakes, the faster the truck wanted to accelerate through the intersection. Fortunately for me there was no other traffic as I didn’t stop until far into the middle of the intersection. I would have been convinced my truck experienced unattended acceleration, except for the fact, out of the corner of my eye when all this excitement was going on, I looked down at my foot and noticed that while my foot was pressing firmly on the brake pedal, the very edge of my shoe caught the gas pedal and it hit me what was going on. I never felt my foot hitting the gas pedal, and never before or since had this happened. But for a brief second, I had my foot just at the necessary angle to hit both the gas and brake at the same time. I would have bet money that I wasn’t pushing on the gas except that I saw it happen. My shoe was just barely touching the gas pedal, but just enough to cause my truck to experience unattended acceleration symptoms. Wo would have thought? Has anyone else experienced this?

Yes, I notice on my early 90’s Corolla I sometimes (& accidentally) slightly press on the accelerator when my foot is on the brake pedal. But it’s easy for me to tell when this happens, and easy to correct for. It might make sense for the auto designers to reconsider the configuration of the pedals. Maybe the brake pedal should sit proud, up higher than the accelerator. Or maybe the pedals should be further apart.

I have also had this happen a number of times, most often right after I get a new pair of boots. I only ever wear work boots, and tend to wear them until long after they should have been discarded due to wear, usually about a year. The new, unworn soles are so much thicker than what I’m used to that this becomes more likely with footwear I’m not yet used to. Just something I’ve noticed.

Personally, this is the first thing I think whenever I hear a story of unintended acceleration that includes the phrase “the harder I pressed the brake, the faster the car went”, and people still insist that they know they were not partially on the accelerator. We have had some pretty spirited debates on this forum with people posting about this phenomenon. We even had one person start a thread complaining of an accident his wife had due to “unintended acceleration” that included the testament that the harder she pushed the brake, the faster the car went. A few pages later, the poster mentioned offhandedly that his wife has a medical condition that causes lack of feeling in her legs. That could have something to do with it.

Unintended acceleration is fact. The part that’s fiction is the cause of it. The truth is…most of the time unintended acceleration is caused by the driver. All vehicles come equipped with “neutral” or the ability to turn the ignition off. An alert driver can stop unintended acceleration in a moments notice.

@missleman … some media reports have said that some newer cars – just the way they are designed – they can’t be turned off or shifted into neutral when this occurs. Not sure if this is true or not though.

I use my left foot for the brake. Always have, always will even before drivers training. So that’s not a problem for me. Its never happened to me, but like I said I did notice our Olds just speed up while the technician and I were looking at it. With all the computers and interconnected systems, there is more than one way for a signal to be sent to the computer in my view. I also will never believe that that California Highway patrolman that went off the cliff at 90 mph wasn’t trying to do everything possible to stop it and really can’t see a floor mat doing that.

@bennyandthejets-- I understand what you are saying. I have a size 14 foot and have occasionally caught my foot on the accelerator when braking. I was less apt to do this before we had power brakes and the pedal was higher, forcing me to lift my foot to brake rather than slide it over from the accelerator. Also, with a manual transmission, I would disengage the clutch while coming to a stop, so there was no way that the car would accelerate.
What used to drive me crazy back in the late 1950s and early 1960s were foreign makes that had small pedals that were close together. I almost had to turn my foot sideways to operate these pedals individually. The roller pedal for the accelerator on the Morris Minors was particularly difficult for me to operate.

I think the solution would be to either make the pedals slightly further apart, or make brake pedals in all cars like they do in manuals, narrow, but the same distance from the gas. I’ve got big feet, and while I haven’t had the issue of pressing the gas when I was trying to get the brake (I think I have done the reverse, but that’s usually obvious and not dangerous). Another thing would be to stop screwing around with all of this keyless ignition and funky transmission controls business. If something was wrong with the computer, causing unintended acceleration, it seems likely that it would ignore the engine on/off button or transmission control if they weren’t at least quasi-mechanical. You at least know a key will turn the thing off. At any rate, I’m going to buy manuals as long as I can to at least maintain some semblance of control over the car.


"... will never believe that that California Highway patrolman that went off the cliff at 90 mph wasn't trying to do everything possible to stop it and really can't see a floor mat doing that."
Why did he not shift into NEUTRAL? Understandable that in a panic he may not have pressed the ON button 3-seconds to turn the engine off. I do not see the floor mat causing a problem at all. It is not stiff enough for great acceleration. I can see it cauing slight acceleration. My wife and I have practiced shifting into neutral without going too far into Reverse.

I’ve had a few gosh moments in trucks that had the accelreator and brake pedals on a different plane,I’ve also remember a camera in a stock car watching the braking action,the driver had absolutely no idea he was on the brakes so much(and this is a professional) the point is people panic and stomp the daylights out of the accelerator trying to stop and needless to say it doesnt work, have seen a few instances were engine rpm exceeded input,but its pretty rare.
Most folks dont want to admit they couldve screwed up,it sorta really makes you wonder about the level of competence with some drivers when this woman with the runaway Toyota called her husband on the cellphone and said goodbye for several minutes,I guess the brakes failed too-but all that aside there must have been something wrong with toyotas because of the settlement the company(either that or F Lee Bailey type lawyers suing)-Kevin

I worked on embedded microprocessor systems for over 20 years. If the throttle is microprocessor controlled, or the equivalent in programmable logic, it is certainly possible to have a runaway condition.

In the mid-70’s, I worked on a microprocessor based area navigation computer for small aircraft. (Lear jets, etc.) One day I got a call from a field service engineer (since all our actual engineers had been hired away at big increases in pay) who reported that if one changed a cockpit switch within a certain time slot of changing waypoints, the computer reported that it has locked in on the new waypoint setting, but actually continued to follow the same track forever, or until you ran out of gas. I verified it on the test set. Scary.

Also, I worked in the 80’s and 90’s on a box for a well known military aircraft. It has a "watch dog timer’. As the software bounced around between various software modules, at each module, it commanded a reset on the timer. If it didn’t get one soon enough, the microprocessor was re-started because the timer timed out.

I called the Senior lab tech one day and asked him if he knew for sure the period on the watchdog timer. There was a stunned silence. He told me it should never fire, since it only served in the unlikely event the software froze. I well remembered that periodic pulse, I just couldn’t remember the exact period. When he investigated, he learned that 400 times a second, that software crashed, and the processor had to do a soft restart, which means it looked in RAM and found out what it was supposed to be doing and continued. And, in flight, no one noticed.

The good news was it did not involve primary aircraft controls, but was in the communication system.

The bad news was this aircraft at times flies over your houses, while carrying large amounts of high explosives. Still in use today and will be for a very long time. I often wondered if they fixed that or not.

When I heard about the runaway cars, I believed it is possible, if the Toyota programmers didn’t know to put a watch dog timer function in the control module. Not just possible, but PROBABLE.

Even if the processor does not fail, each important peripheral circuit needs a fail-safe design. For example, if the command module sends signals to the throttle control, what happens if that signal is lost? Does it automatically return to zero throttle, or does it lock in place due to failure of a command to return to zero.

And, of course, on the throttle position data similar problems could occur causing the command module to believe full throttle is commanded.

I will try to keep my 2002 Sienna running as long as I can.

Let me add I have big feet. I have driven with two feet since 1973, which has prompted some here to accuse me of being a bad driver since 1973, which is really lame. Even as driving coaches in NYC teach commercial drivers to drive with both feet for reduced response times. Part, but not all, of my decision to drive with both feet is to avoid simultaneous pressure on brakes and throttle as described well in this posting. Driving two feet is only safe when you always drive automatic transmissions. It takes about two weeks to become properly adapted.

I’m of the opinion that unintended acceleration due to a mechanical fault is a possibility and likely has happened on occasion. However, I do not think it’s as common as portrayed and most instances are due to someone screwing their feet up; followed by being too embarassed to 'fess up or honestly thinking they did not screw up after some reflection on the matter.
The ones that are really suspect are the drivers who claim they did everything under the sun and nothing worked.

I wear a size 11 and a few times in the long ago past (with an automatic) or more recently with a manual, I’ve found myself catching the edge of the accelerator pedal depending on the type of shoe or boot worn.

Personally, with most of my driving being with an automatic transmission I drive with both feet and have for decades. It’s second nature and has never led to an inadvertent tap of the accelerator pedal.

my question is on say a prius ,do these things not have kill switch,good brakes or nuetral posistion) a clump of rose bushes will stop you or soft and boggy ground-Kevin

OK, my feet are size 13, which is why driving with two feet, always on automatics, is so important to me. I started driving with two feet in 1973.

My so far unanswered question, on several fora, same as Kevin’s, is do the Toyotas have any sort of kill switch; or hard neutral position not depending on computer control. I think I posted my experience with aircraft computer that did horrible things due to software errors.