Obvious Question About Run Away Cars (Like Toyota)

struwwelpeterMarch 9, 2010

What happens if you turn off the ignition?

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If by ignition you mean turning off the key, that is the problem. They don't have one. One of the models they are having the problem with has a start button. You have to press that 3 times to turn the engine off. Who knew that? It's in the owners manual but is well hidden along with tire inflation and seat belt adjustment.

    Bookmark   March 9, 2010 at 4:30PM
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Suppose it is a car with a key?

    Bookmark   March 9, 2010 at 7:30PM
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If you shut the engine off, several events happen. However, an expereinced driver should be able to handle these.

1. You will loose a re-supply of vaccuum for the power brakes. Several sytems have enough stored vaccuum to effect one power assisted stop. Do not pump the brakes. Each stroke of the brake pedal depletes vaccuum. However, the brakes will work just fine without power assist except that the pedal effort may be doubled.

2. If the vehicle has a power steering pump, you will loose power steering right away. The steering will still work but it will feel stiff.

I'm not sure what happens if you have an electrical assisted steering. If you have a fully electrical steer by wire, you'd better have a good battery to carry you through the crises.

3. You may loose engine braking depending on the design of the transmission. Early automatic transmission had pumps on both the input and putput shafts. If the output shaft was spining fast enough, there was enough hydraulic pressure flow to operate the transmission. Later, the rear pump was omitted. These transmissions will drop out when the engine stops.

But if you have a manual transmission, you already know its behavor and what to do.

4. The best part is you will shut down the runaway engine.

    Bookmark   March 10, 2010 at 1:04AM
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To shut down the car with a start button, you must press and hold the start button for more than three seconds. Before all of this started a few months back technicians didn't know that either and there was not really a need to know.

One of the biggest problems we face right now is that none of these cars have acted up in the presence of a technician who has the training and skills to test and prove what is going on as far as I am aware of. The "professor" who rigged a car and forced it to runaway didn't do anything that a first year electronics student couldn't do. He simply went outside of the pedal assembly, and created and then sent signals to the computer that matched what the computer expects to see if wide open throttle is commanded by the pedal assembly potentiometers. Notice of course "potentiometers" is plural. That is because there are two of them in the pedal assembly and the computer constantly compares the signal between the two of them for rationality. If one of them isn't reporting correctly limp in mode is commanded, and the system can only reach a minimal throttle position. Due to separate ground circuits, reference circuits, and of course signal return circuits the possibility that the professor attempted to show is simply not going to happen, the system is designed to prevent that.

Some say "it's in the computer" or "electronics". They for the most part also don't have any first hand experience and don't understand the fact that the two potentiometers don't work identically. One operates on a different scale than the other, so if something pushed ground circuit voltage high, that would cause a rationality check to fail and would disable the throttle system.

I'll say it right here. What we need is for someone to experience a runaway, put the car in neutral and slow down and stop. Get out of the car without shutting it off and let the thing bounce off of the rev limiter until it runs out of gas, breaks, or until a qualified technician gets to the car to directly examine what is going on. Will it hurt the engine? Maybe, but there is a hefty prize awaiting the person that actually solves this puzzle. We could afford to replace an engine if we won that prize. :)

Through the years you all have seen me write about what it truly takes to do diagnostics. This is no different, we have to experience the problem to accurately diagnose it. Anything less than that amounts to guessing, and when you guess on an intermittent issue you never truly know if you fixed it until the stupid thing acts up again which only proves that you didn't. For the vehicle owner, they are left to walk up to the car each time they drive it wondering, will today be the day that I find out that it wasn't fixed yet? Everything about all of this comes down to one thing, proof. Proof that any individual claim is factual, proof of the actual cause if the first is verified (which means it must happen again consistently for the technician to complete the required testing), and lastly proof that the repair has verification that it solves the problem. I don't see where we have any of that at any level. That does not mean I am denying the stories, there are too many to simply dismiss them. But there are still other possibilities at play.

I have a 2005 Camry in the shop right now, and had a 2008 Avalon in yesterday. I did confirm to myself that stepping on the throttle and the brake at the same time is not only possible with both cars, I could not stop either car when I hit both pedals simultaneously with only my right foot. That I can prove, and I could see where once the brakes heat up and fade the cars would easily run away, especially the Avalon. Now in both cases there is plenty of room to take my left foot and hit the brake pedal and lift my right foot, which of course releases the throttle and both cars easily stopped.

The cars will shift into neutral even under full acceleration. The idea of someone racing down a road at 90+mph for thirty minutes, well, lets just say there are safer ways to get on TV. If you experience a runaway, shift it into neutral, pull to the side of the road and stop and just let the engine race until it can be proven what is going on. If you want to start investigating yourself, go under the dash and find the wiring harness to the pedal assembly. Fist make sure the pedal isn't stuck down by manually lifting see if that possibly helps return the engine to idle. Then go ahead and unplug the pedal assembly and see if the car continues to race, or if that forces limp in mode and the engine returns to idle.

Beyond those checks, you would need a scan tool to read input data and output commands from the PCM. (fuel injection computer).

Perform any of the steps I mentioned at your own, and your cars risk. I am only telling you what I would have to do at this point if I got to experience this phenomenon.

One last point. Manual trans-missioned cars use the same pedal assembly, the same computer, all the same electronics etc. Does the absence of complaints from owners who's vehicles use a clutch seem noteworthy?

    Bookmark   March 10, 2010 at 7:18AM
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You may well be on to something, there. Maybe because I know cars, but it just seems like common sense that if the accelerator is stuck, shift it into neutral. And if a floor mat is stuck, kick it out of the way. Granted, I'm sure it isn't just from a floor mat, but the point is that if people behind the wheel had a clue about what to do in an emergency, most of these wouldn't be news stories. If the people who are driving sticks aren't having problems, perhaps part of the issue is with the people driving it?

    Bookmark   March 10, 2010 at 9:48AM
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Won't shifting to neutral likely cause the engine to rotate fast enough to break a connecting rod? Suppose the panicked driver accidently shifts to reverse or park?

    Bookmark   March 10, 2010 at 10:54AM
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we have 2010 camry LE 4cyl auto. recall has been done. tech assured us shifting to neutral is mechanically controlled. not computer controlled. so i feel pretty confident going to neutral will work. i read about a test online. they held the gas down and applied brake with other foot and car had very poor stopping power due to low engine vacuum at wide open throttle. i don't really want to try an experiment but does that sound plausible?

    Bookmark   March 10, 2010 at 11:24AM
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i feel pretty confident going to neutral will work.

Of course it will work to stop, but, the question is, "Will that severely damage the engine?". I am talking about over $500 damage to the engine.

    Bookmark   March 10, 2010 at 12:26PM
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and how do you guarantee that it will work? the 2010 camry shift linkage is 100% manual. no electric solenoids for shifting from park to drive?

    Bookmark   March 10, 2010 at 1:04PM
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I don't know if you've attempted to shift a modern automatic into reverse or park while it is going more than 10mph, but in my experience its almost impossible to do. Even if you were able to do it, it would most certainly help to slow down the vehicle. If you are really all that worried about engine damage, keep it in drive while you crash into a tree. Then ask yourself which damage costs less to fix. And, if the vehicle is still under warranty, Toyota would take care of any engine damage. When given the choice, I would put it in neutral every time.

    Bookmark   March 10, 2010 at 1:10PM
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I think I have heard rumors of thrown connecting rods killing people. Thus, I would prefer to turn off the ignition than shift to neutral.

    Bookmark   March 10, 2010 at 3:36PM
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just went out and ran a few tests. with full acceleration i can shift from drive to neutral. takes a second or so but it will go into neutral. tried it at 25mph and 55mph. worked both times. but who knows if it will still do that when the "computer" goes crazy?

    Bookmark   March 10, 2010 at 4:59PM
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"i feel pretty confident going to neutral will work.
Of course it will work to stop, but, the question is, "Will that severely damage the engine?". I am talking about over $500 damage to the engine."

At that point I consider it like choosing between running into the ditch or running head on into an 80k lb semi truck. I'd pick the ditch. The damage I wouldn't care about.

    Bookmark   March 10, 2010 at 9:32PM
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Lets assume for the sake of discussion that you own a car and it has 200,000 miles on it and it does a legitimate runaway, so you throw it into neutral, and blow the engine while you safely slow down and pull to the side of the road. Does it really matter if you broke an engine as compared to hurting yourself, your friends or family that might happen to be with you, or some other person?

We can fix/replace engines. We cannot fix you, your loved ones, and/or someone else's.

Thank-you Joe mn for playing with your car to see what would happen. That's real world, not the hype you see on TV.

Heck today was one of those days that I am glad is over, but it's also not without it's ow chance at some levity over the situation.

Today I am out of my shop and teaching in the New York city area. So I had to fly in and rent a car. Everything was set for me to fly into White Plains (West Chester) but there was a problem with the first airplane that was to take me to Philly, so it was going to be impossible to make the connection to get here. The only choice was to change destinations and I then had to rent a car in LaGuardia instead of White Plains. After a considerable delay, they finally gave me a choice of four cars. I took the Toyota in the hopes that first of all if I got caught driving too fast I might have an excuse, second if it actually did act up for me it would be like hitting the lottery! VBG....

Alas, no such luck. The car worked flawlessly. Oh well, there is still tomorrow.

BTW, I can hit both pedals with one foot simultaneously on this model too. At the same time I must point out, that my being able to do so intentionally has no bearing on what is actually happening in the reported incidents.

    Bookmark   March 10, 2010 at 11:25PM
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Yesterday when I replied that one way to stop an engine was to turn off the ignition. This may not be practical on some cars. YOU DO NOT WANT TO LOCK THE STEERING COLUMN. For the three vehicles that my family owns, all have key switched ignitions and all have 4 positions: Column locked, off, run (or ignition on) and start. When turning off the ignition, be careful to turn the key only one detent. If you turn the key back 2 dentents, it will be at the column lock position.

I am not familar with the setup on the newer Toyotas. I read above that one shutdown procedure was to hold the start button down for at least 3 seconds, and not many knew about this including some Toyota technicans. I'm curious: What is the normal shut off procedure, for example, after you pull into your garage?

    Bookmark   March 11, 2010 at 1:39AM
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When you pull into your parking spot, you simply hit the power button and the car turns off. At 0mph, the car instantly recognizes that command. Now at speed (moving) the car ignores that same button push because if someone inadvertently hits the button Toyota doesn't want the car to shut off on them. Just think of all of the complaints that would have caused. That's why you have to press and hold the button for three (several anyway) seconds.

    Bookmark   March 11, 2010 at 5:54AM
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Will pushing that "button down 3 seconds" lock the steering column?

    Bookmark   March 11, 2010 at 10:50AM
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Good question, don't know for certain.

    Bookmark   March 11, 2010 at 12:18PM
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I don't blame anyone on this forum for not knowing the answer, but, I certainly blame the news media for not anticipating and answering obvious and useful questions such as this. Instead, the factions of news media blindly copy each other's relatively useless but entertaining sensationalized news.

    Bookmark   March 12, 2010 at 10:47AM
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I don't recall anyone finding fault with the Media when Ford was having the issue with people running around with under-inflated tires, which resulted in the sudden failure of the tire and a roll-over accident. The media crucified Ford and Firestone, and ultimately they were not at fault. But you never would have known that based on the news.

    Bookmark   March 12, 2010 at 3:12PM
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The plot, or should we say "plots" thicken.

Here is a link that might be useful: Sikes Prius Runaway

    Bookmark   March 15, 2010 at 5:02AM
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>> A Toyota official who was at the inspection explained that an electric motor would "completely seize" if a system to shut off the gas when the brake is pressed fails, and there was no evidence to support th....How's that? Do you believe that? I don't!

In school in EE lab we had a motor get away from us. Before it was stopped there were pieces of it embedded in the ceiling walls and floor. It sure as h*ll did not sieze. I recall it was a 3-phase motor started on 1-phase then you switched to 3 phase but it didn't get switched so it kept winding up.

    Bookmark   March 15, 2010 at 11:35AM
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Every electrical motor has a maximum rpm that it can turn without sustaining damage. Once that speed is exceeded, centrifugal force will pull the windings from the armature and they will bind into the stator. In the case of the Prius transaxle we are actually talking about a rotor assembly that has permanent magnets attached to it. Exceed the rated speed of that rotor and it will grenade. The engineers are correct.


In order for the gas engine to propel the car, MG1 actually has to be a generator and provide resistance for the engine to push against, as well as MG2 being a motor that helps the gas engine push the car. Using the java applets on the site I provided you get to see the normal operation of the motors in the transaxle, and how they work together. Take note there are times that MG1 actually is forced to spin backwards.

The Prius has a maximum vehicle speed of 94mph, with the primary reason being risking over-revving the electric motors and causing a catastrophic failure of the transaxle.

Here is a link that might be useful: Prius Power Split Device.

    Bookmark   March 15, 2010 at 4:24PM
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Thankyou John - that is quite an interesting and descriptive site.

However. I spent 11 years as an engineer engaged in scale model research in the 1960's and there were times when what ever happenend "couldn't happen" according to the design group. They weren't there, didn't see it, didn't believe it, would NEVER acknowledge that it happenend. Even with witnesses. After 40+ years I still have bitter feelings.

So I remain sceptical.

Incidentally I drove truck to get thru engineering school. After 11 years I went back to driving - MUCH the preferable profession. :-)

    Bookmark   March 16, 2010 at 12:52PM
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Your welcome mx. I havent spent enough time on that, and especially all of the other sites like it, and linked through it myself yet to see everything these guys/gals are figuring out about these cars. There just isn't enough time in the day for that anymore.

Now back to the topic. Your gonna love this one.


Yes the Toyota's do indeed have black boxes and this one that they have released the data on from a crash that made national headlines showed; There was no brake pedal input, only wide open throttle commanded by the drivers inputs.

Here is a link that might be useful: Toyota Black Boxes

    Bookmark   March 18, 2010 at 10:25PM
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