Toyota Throttle Electronics Easily Confused
in [Technical]
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From: JoeSpareBedroom on 25 Feb 2010 10:09 "C. E. White" <cewhite3(a)mindspring.com> wrote in message news:hm6346$ukt$1(a)news.eternal-september.org... > > "john" <johngdole(a)hotmail.com> wrote in message > news:632aabcb-70bd-4397-879b-f6da50eb972f(a)l12g2000prg.googlegroups.com... >> The floor mats and sticking pedal accounts for only 30% of the >> problems. The true cause of sudden acceleration is still not known so >> no real solution is possible. IMO it's the electronics. >> >> "In earlier testimony, David Gilbert, a Southern Illinois University >> professor, tells the panel he was able to produce in a lab environment >> a sudden-acceleration incident using a Toyota vehicle, in essence by >> introducing a short between two circuits. > > Consider who is paying for this research....Trail Lawyers! > > This is eerily like the Audi 5000 frenzy. When 60 minutes did their > hatchet job on the 5000, they produced an "expert" who "proved" that the > 5000's automatic transmission could force a kick down of the accelerator > pedal, resulting in sudden acceleration. Good old Ed Bradly presented this > as some sort of scientific proof. Only later did we learn (and not from > CBS) that the expert added an extra hydraulic pump and external piping to > demonstarte this "failure" mode. > > There may or may not be an actual problem with the Toyota electronics. But > an "expert" that creates shorts to "prove" there is a problem is not the > sort of expert I trust. > > Ed > I see no indication that any expert claims to have proven anything. Maybe you're interpreting something differently than I am. Please highlight the words you read and surround them with five asterisks on either end of the phrase, *****like this*****.
From: Steve on 25 Feb 2010 10:37 jim beam wrote: > On 02/24/2010 09:19 PM, Uncle_vito wrote: >> Made in Japan only applies to the accelerator fix. If it is a software >> problem, all bets are off. Could be in cars no matter where made >> since they >> do noit know the cause. How can they say which cars are not affected? > > dude, it it were a software problem, /all/ their vehicles would be > exhibiting the exact same problem all the time. So you believe that they use exactly the same software build in every vehicle? ROTFL!!!
From: C. E. White on 25 Feb 2010 10:37 "Hachiroku ????" <Trueno(a)e86.GTS> wrote in message news:hm4351$u8r$1(a)news.eternal-september.org... > Right. There will be no problem with your gas pedal binding up due > to > corrosion. As I understand the explanation, the problem with the CTS pedal assemblies is not "corrosion." It is moisture condensing on the plastic components. This changes the frictional characteristics of the assembly (possibly becasue they are using some form of nylon which absorbs moisture and swells). One thing that did catch my eye was the fact that both sides of the assembly used the same plastic material. I was taught this is a no-no when designing bearings (rotational and linear). When you use two identical plastics on opposite sides of the same frictional assembly, there is a tendency for the two plastics to "stick" together with age. I have a chart (a very old chart now) from Machine Design that lists compatible plastics for these type of assemblies. They never recommend using the same plastic on both sides of such an assembly. It seems to me as these pedal assemblies wear, the plastic surfaces become very smooth, and therefore even more likely to stick becasue of the plastic "compatibility." If the parts are nylon, moisture would likely make the problem worse. Adding the metal shims, would fix this, since plastic sliding friction on hard metal surfaces is much more predictable that plastic on plastic. > The reported problem is that the area around the spring corrodes, > and > keeps the spring from returning the pedal to idle position. The shim > keeps > the spring from binding. This is not the explantion I read. The shims actually change the frictional surfaces from plastic on plastic to plastic on steel. The original plastic on plastic rubbing acted as a damper / drag to give good pedal feel. I don't beleive the problem was related to corrosion at all (see above). There are interesting pictures at: http://www.thetruthaboutcars.com/toyota-gas-pedal-fix-simulated-friction-reduced-but-by-too-much/ > Since your pedal was sourced from Japan, and not CTS in the US, it > does > not have this problem. Are you sure this is true? I haven't been able to find a decent description of the Denso pedal assembly. Are you sure it is that much different? Got a link to pictures? > But here's a hint: turn your cruise control OFF when you're not > using it. > OFF, not just Cancel, or hitting the brakes. OFF. Since most current cruise controls (and by most I am including manufacturers other than Toyota) use soft switches (i.e., switches that send a signal, they don't actually disconnect the circuit), I doubt if this makes any difference. Both "cancel" and "off" just send a signal to the computer telling the computer to initiate a function. Off is just a different signal than cancel. In the old days "off" actually cut the power to the cruise control. Now for many autos, off only means, "don't pay attention to other cruice control inputs." Ford got tired of people blaming the cruise controls for UA, so they added the stupid brake line switch to physically cut power to the cruise control actuator when the brakes were pressed. And then this screwed up. Fix a bug, add a bug.... I'd be tempted to go back to vaccum operated cruise controls! Ed
From: C. E. White on 25 Feb 2010 10:46 "Tegger" <invalid(a)invalid.inv> wrote in message news:Xns9D2A4B185CB99tegger(a)208.90.168.18... > Or it's simple pedal misapplication, which is the most common cause > of SUA > by far, and is essentially out of /any/ automaker's control. Not really - software that recognized both pedals are pressed could cut power to the engine. The shift interlocks that force you to press on the brakes before shifting into gear were a "fix" for the Audi 5000 UA concerns. If the Safety Nazis get there way, there will be so many fixes for potential/theoretical driver errors, that cars won't be usable, or affordable. Ed
From: Steve on 25 Feb 2010 10:52
Tegger wrote: > > The lab that Toyota retained managed to reproduce Gilbert's result, but > said that they found it extremely unlikely that such an event could > actually occur in the real world. > > The problem here is that people just don't understand the mathematics of probability theory. Something that occurs once in 100,000 vehicles over a 5 year period is "extremely unlikely," I think everyone can agree. But if there are 8 million vehicles on the road, that is 8 million "tries" and statistically the event should happen 80 times in 5 years. No manufacturer is EVER going to make it 100% certain that the ECU doesn't get a false wide-open throttle command for the simple reason that there are electromechanical sensors involved which can fail, and wiring can fail. That can be made very rare, but not absolutely impossible. What every other manufacturer DOES do is put in logic so that touching the brake pedal immediately overrides the wide-open throttle command and brings the engine back to idle, even if its still getting a WOT command from the (faulty) pedal mechanism or wiring. |