Most resisitive throttle position sensors will have two sensors, and for a given throttle position each sensor sends a different value. With the different values for a given throttle position, the ECU can determine when there is a problem and go into the limp-home mode if required.
I agree with your wife. Toyota was unfairly "bashed" in many ways. The bottom line with the horrific crash of the ES350 in San Diego was a jammed carpet mat, a mat from an RX350 that had been installed inadvertently by a hired hand at the dealership. The crash had nothing to do with tin whiskers or any computer malfunction.
I also would like to comment about German vehicles. Their overall reliability, according to Consumer Reports, is still well below that of many Japanese vehicles. Their performance and customer "pampering" lure in buyers who often overlook the inconvenience of having to take their vehicles in for not-very-infrequent repairs.
Whiskers had been found and photographed by NASA scientists. There is no problem with the fact of whiskers.The problem is that we live in the world that covers the truth.They should just say:we found a problem.Bring the cars and we will correct it.Thing is that mat takes no time, changing design and construction of a module takes a lot of time.They are back on top and they will take care of their customers like they always did.They are probably using a supply of service parts now, which is a temporary fix, because they are defective like originals....unless problem is already fixed in those.
To other friends: We are talking about cars that were built after ROHS (no lead) rules.Toyota is not an exception.All electronics fails left and right and one year warranty disappeared from the market and is replaced with 90 years warranty.
A known fact is that most of electronics manufacturers give their products 4 years life span, which means that garbage can is a destination after 4 years.How about your parents, or grandparents 15 year old Zenith TV set.....well that's an ancient history.
There are expensive methods to slow it down , but it includes special print on super-epoxy masks and increase of distance between PC board traces...and it is not inn today's world.Everything has to be tiny......and it breaks after 30 -90 days.Nothing , except metal inhibitors can stop whiskers' growth.You are absolutely right.
It's with interest and surprise to see the debate about the recent problem being addressed by Toyota. It was a surprise that it still being discussed. It,s also a surprise that the cause is still unknown or that a probable cause has not been articulated. Is it possible that tin whiskers caused the problem? The answer is yes but what is the probability that it is the cause. I would suggest that it's very low. Although we do not fully know what triggers the mechanism, there are a number of factors that have to be in place for it to occur such as humidity, material stress, humidity, etc. Also', we also know how to get rid of it So what is the big issue? If whiskers is the problem, why the debate?
I would suggest that perhaps a different mechanism may be at work --- Fretting Corrosion. This mechanism is a result of low amplitudes of movement (as low as 0.001 to 0.003 of an inch) that can occur with all material systems including tin, nickel, copper and even gold (gold wears exposing under plate or other non-noble substrates). This mechanism does create momentary interruptions in electronic systems(we've been involved with this issue for since the 1970's). When a contact moves on a "bad" spot it will cause a fault. As motion continues the contact will move off the "bad" spot to a "good" spot and the fault will disappear. These faults can be as fast as 2 nS. Unfortunately, fretting is not predictable.
I will stop at this point. My frustration is that everyone is jumping on Toyota trying to fix the cause that is being described as tin whiskering. However, where is the conclusive data to show that it is. Fretting has a higher probability but there is no data to prove this either. Why can't Toyoata indicate what they have investigated with data to prove or disapprove the condition so we can move on to the next situation?
Nice article, Chuck. If tin whickers might be the failure that caused the unintended acceleration, that means a failed component could be the culprit. I would think the discovery is a matter of determining what component failure (if any) would result in unintended acceleration.
Hi Chuck-IAG... I'm actually a MOPAR fanboy and have owned a Dodge 400, Dodge Caravan, Dodge Stratus, Chrysler Sebring Convertible, Dodge Durango, and our current toy hauler is a 5.7L Jeep Grand Cherokee. I'm not a mechanic, but I have a code reader and a socket set and have switched out my share of thermostats, temperature sensors, oxygen sensors, and throttle-position sensors. We have put over 300K miles on the Corollas and the most I have had to switch out is light bulbs (thankfully).
The 2003 1.8L Turbo Automatic VW Convertible New Beetle was a different beast altogether. My wife fell in love with the styling and she is still heavily mourning its loss. My comments here were not to start a flame war, but on the topic of Design, the VW was in its own league. I only learned that Volkswagen was the parent of Audi, Bentley, Bugatti, Lamborghini, Porsche, and Ducati after we purchased the Bug from a reputable local dealer that sells only late-model used cars. What I didn't expect was that after the Bug started to lose sensors and electronic controllers that there are practically no user-serviceable parts and that we would need to take it to the dealer and pay Porsche repair prices for a VW. After a $9000 quote from the dealership to replace the trans at 75K we traded it in as salvage.
My overall point was that my experience with Toyota is not only have they been the most reliable cars we have owned, they are also the easiest to maintain -- designed with repair in mind. -- Rather than designed for exacting tolerances and then handed over to highly-skilled mechanics to fix when broken.
Perhaps some day when I have a Lamborghini repair budget on hand, I will consider VW again...
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