The NHTSA investigation into the unintentionally accelerating Toyotas has not satisfied Iowa Sen. Charles E. Grassley. He says NHTSA and its team of NASA engineers spuriously ruled out a possible electronic fault that could have caused the cars to malfunction.
The senator has sent a letter to NHTSA administrator David Strickland regarding the probe. In it, Grassley accuses the investgative probe of being “too narrow”. According to the senator, whistle-blowers recently testified to him that the electronic throttle system could have malfunctioned due to a phenomenon called “tin whiskers.” They also provided him with documents regarding the electronic throttles of Toyota models.
The unintended acceleration plague that took place in the summer of 2009 was eventually blamed on floor mats. The ten-month long NHTSA investigation concurred that the accelerator pedals of certain Toyotas could be trapped under poorly installed floor-mats.
According to the NHTSA report, tin whiskers are “electronically conductive, crystalline structures of tin that sometimes grow from surfaces where tin (especially electroplated tin) is used as a final finish.” The senator’s letter, dated July 12, asks NHTSA to provide the Senate Judiciary Committee with all testing data on the phenomnen of tin whiskers. It is not a new issue, having been common before the 70s and 80s when lead became dominant in electronic connections. A ban on lead in soldering has brought it back as a problem.
Toyota has issued a statement saying “no one has ever found a single real-world example of tin whiskers causing an unintended acceleration event.”
“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,” said Toyota. In the event that they do connect to nearby circuits the fail-safe recognizes this and puts the car in a “limp home” mode. This cuts the engine power to a minimum that lets the driver put the car on the road’s shoulder out of the flow of traffic.
Grassley also asks Strickland why NHTSA used NASA engineers to lead the investigation. He ask if NHTSA has “the sufficient expertise to conduct such investigations and why.”