Editor's note: Tune in tonight at 8 and 10 p.m. ET for Drew Griffin's update on the investigation.
U.S. Sen. Chuck Grassley, R-Iowa, is asking the National Highway Transportation Safety Administration to look into additional questions about unintended acceleration of Toyota cars.
Citing unidentified whistle-blowers critical of "too narrow" federal investigations, the ranking member of the Senate Judiciary Committee asked the NHTSA in a letter to look into the phenomenon of "tin whiskers" - or crystalline structures of tin - that theoretically could lead to the unintended acceleration.
The whistle-blowers also provided Grassley with documentation about the investigations by NHTSA and NASA into the Toyota vehicles, including one NASA report that stated: "Because proof that the (electronic throttle-control systems) caused the reported (unintended accelerations) was not found does not mean it could not occur."
Grassley's letter to the safety agency's administrator, David Strickland, asks the agency to provide the committee with all information relating to tin whisker testing and for the agency's position on tin whiskers' possibly causing the unintended acceleration.
Strickland and his agency didn't immediately respond Thursday to a CNN request for a comment.
A Toyota spokesman told CNN Thursday that "so-called 'tin whiskers' are not a new phenomenon and do not represent a mysterious or undetectable problem in a vehicle's electronics."
Last year, a federal investigation into possible causes of the unintended acceleration in Toyota cars found no fault with the automaker's electronic throttle-control systems, the Department of Transportation said. So far there are three known causes of unintended acceleration in Toyota vehicles: improperly installed floor mats, sticky pedals and driver error.
Toyota spokesman Brian Lyons said Thursday that "all the scientific evidence" confirms there's no problem with the electronic throttle-control systems in Toyota vehicles.
"Indeed, no data indicates that tin whiskers are more prone to occur in Toyota vehicles than any other vehicle in the marketplace," Lyons said in an e-mail to CNN.
"Further, no one has ever found a single real-world example of tin whiskers causing an unintended acceleration event, nor have they put forth any evidence of unintended acceleration occurring in a Toyota vehicle because of tin whiskers forming inside an accelerator pedal position sensor," Lyons said.
"Toyota's systems are designed to reduce the risk that tin whiskers will form in the first place and multiple robust fail-safe systems are in place to counter any effects on the operation of our vehicles in the highly unlikely event that they do form and connect to adjacent circuitry," Lyons said.
hello my name is Jim I've owned a toyota camry . Since 2009 and put 65,000 km on it and the only problems I've had with it is when I'm climbing a hill and the transmission shifts down it will shift so hard and so fast that it seems like the throttle is sticking by I've played with it and come to the conclusion that it is the transmission shifting down so fast and so hard that the car doesn't have a chance to catch up. And if you have the your foot on the throttle you could be a lot of trouble in hurry. On icy roads car will crawl out from underneath you if you don't back out of the throttle. I have some other problems but like when I put my arm on the armrest. It breaks, I take it back to Toyota and they make me wait and wait and wait some more. And then it put the same crap . Back into my car and soon as I use it it breaks again, 250 pound man 6 foot three, so I thought possibly it was me slightly is not my wife's 5 foot three slightly over 100 pounds I see her sides broke to . Another thing really impressed me about my Toyota car is the fact. My salesman told me it gets 46 miles to the gallon. I think it's 36, myself, maybe 37. So it seems to me the hype about Toyotas isn't all it's cracked up to be.
I recently bought a 2011 Toyota Camry. I expressed concern over the acceleration issue with the salesman. He reassured me that the issue had been resolved. The problem was the floor mats were getting caught up under the accelerator and thus causing the acceleration issue. I can't help but wonder when people were experiencing acceleration with the cars why they didn't just turn off the ignition. I think I'd rather have to replace the transmission than kill myself or someone else.
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