Electromagnetic fields, or EMFs, are produced in varying frequencies due to their source: electric currents, power lines, radio and microwave antennas, airport radar, even cell phones. Cars also produce low-frequency magnetic fields.
According to one theory, electric signals can briefly interfere with the electronic controls of cars. As Toyota issued recalls over the matter of sudden unintended acceleration - blaming faulty pedals or obstructive floor mats - the possibility of interference by EMFs with Toyota's electrical systems has been raised.
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Last December Toyota commissioned a study on its cars' electronic throttle controls. In a press release earlier this month, the automaker said Exponent, an engineering and scientific consulting firm in Menlo Park, Calif., was unable to induce unintended acceleration in Toyota and Lexus vehicles equipped with electric throttle control.
"In all cases, the vehicle either behaved normally or entered a fail-safe mode where engine power was significantly reduced or shut off," Toyota said.
According to a draft report obtained by USA Today, Exponent said it could not induce unintended acceleration through "electrical disturbances."
But that isn't quelling the debate. USA Today quotes safety experts who question the thoroughness of the study,
Brian Kirk, a British consultant on software safety systems and an adviser in automotive lawsuits, told the paper that poorly designed ignition wiring could interfere with signals to a car's electronic throttle or engine controls.
Meanwhile, the Rehoboth, Mass.-based Safety Research & Strategies is conducting a study on the malfunction detection and fail-safe capabilities of Toyota vehicles equipped with Electronic Throttle Control, which calculates throttle position based on sensors monitoring accelerator pedal position, engine and vehicle speed and other factors.
Sean Kane, president and founder of Safety Research & Strategies, testified before on the response by Toyota and the National Highway Traffic Safety Administration (NHTSA) on sudden unintended acceleration.
Kane said that preliminary results by his company found conditions in the tested Toyota and Lexus models in which the redundancy of electronic circuitry in the Electronic Throttle Control is lost, particularly in the Accelerator Pedal Position Sensor (APPS).
"Random, intermittent electronic faults are hard to detect, but they do occur," Kane said. "The electrical contacts, electromagnetic interference, and the programming of the electronic controls and sensors are all possible points of breakdown or interruption in an electronic system."
Transportation Secretary Ray LaHood, also testifying before the subcommittee today, said the government is addressing the possibility that electromagnetic interference has played a role in acceleration problems.
"To date, we have not identified any particular crash or unsafe occurrence that can be clearly attributed to such a phenomenon," LaHood said in prepared remarks. "However, to be absolutely sure that the agency is aware of all potentials defects, NHTSA is conducting a review of the general subject of possible EMI effects on [Electronic Throttle Control] systems.
"This is a review of the technological issue, not a defect investigation," LaHood said.