Anybody See This?

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It's not clear what this prof did with his "short." Until more is known, I don't give this much weight. In any case, it again points out the dangers of sensor and software controlled acceleration if not properly implemented. A simple brake overide circuit - as I've heard is used in other cars - may have nipped all of Toyota's problems in the bud.

Reply to
Bob Cooper
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Bob Cooper wrote in news: snipped-for-privacy@news.eternal-september.org:

When cars are brought in to Toyota dealers for the pedal modification, their PCMs are also being flashed to add the override (where possible).

If the PCM senses simultaneous brake/gas application, it will immediately cut power by closing the throttle and shortening injector pulse-width. Left-foot brakers are going to hate the new behavior.

Whether other automakers are /also/ adding brake-overrides to their PCMs is something I have not seen mentioned in the media.

Reply to
Tegger

I've seen/heard it mentioned a few times. Found this

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I expect it will quickly be a requirement for all cars with electronic throttle control, whether voluntary or not.

Reply to
Bob Cooper

What I don't understand is in industry when a critical machine function can become dangerous it is recognized as being potentially dangerous right from the start. The potentially dangerous function will either be redesigned to make it safer, or redundant safety measures will be built in.

You would think that any automaker would consider the accelerator a potentially dangerous function especially considering the indirect control with the electronics involved.

They seem to be adding these safety measures now. Is this not in effect a non public admission of not recognizing a unsafe accelerator design?

Reply to
tnom

A short? Last Saturday I was using my old Skilsaw.It started smoking and it tripped a circuit breaker.I went to the Lowe's store and I bought a new Skilsaw, about fifty dollars.I don't need the next highest price Skilsaw with a laser light.If I can't follow my pencil line, a laser light won't help me at all. cuhulin

Reply to
cuhulin

Toyota still has a problem. During the hearings today, Toyota's president said (If I heard correctly through the corporate doublespeak) that not all models will be fixed by the recalls with the brake over ride reflash. This could get more interesting still... Ben

Reply to
ben91932

Apparently, he shorted both tps signal return wires to power. ( He was stingy with details in front of congress) Whether or not this test was significant, what got my attention was this: On Toyota's, both tps's bias low to high as through throttle travel. IIRC, other mfg's bias the 2 sensors in opposition to each other, which seems to me to make for easier fault detection. Can anyone elaborate on this? Thanks, Ben

Reply to
ben91932

What I got from his testimony is the the signal voltages for 2 sensors are extremely close, making an error more difficult for the ECU to pick up. I didn't hear him mention bias opposition, but he did say that the other mfgs use a wider difference in the voltage of the 2 sensors. He didn't get close to fooling a Buick ECU, but it was very easy for him to fool the Toyota ECU. It probably goes beyond the voltage strength and into the fault detetion programming. But that's just speculation on my part. Toyota was lawyered up at the hearing, and their lawyers have accused the prof of "sabotage." I'm still reserving judgement on this. Not enough info/analysis. The prof seemed to know his stuff, but so did Alan Greenspan.

Reply to
Bob Cooper

The Toyota's failed to set a "fault" code.

Reply to
Ashton Crusher

That has always been my reaction. Imagine if a car maker designed a cruise control without a brake override. Your cruising at 70 mph and you step on the brake and the cruise control responds by trying to maintain the speed at 70 mph. You can implement drive by wire on many cars by just operating the cruise control by hand. This throttle control by indirect means has been around for a long time and really isn't all that new like it is being reported. Handicapped drivers have been using it for decades. The drive by wire throttle doesn't have to completely shut down the throttle if the driver is applying the brake, but it should not be designed to expect that the driver would want to apply full throttle and brake at the same time. An override to the throttle when the brake is applied would have addressed any erroneous TPS sensor problem or the floor mat problem or the step-on-both-pedals problem. It is unbelievable that a design engineer would regard any of these problems as new or unexpected.

-jim

Reply to
jim

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