WERE incidents in which Toyota cars unexpectedly accelerated simply down to driver error? Early investigations of some of the vehicles involved suggest they may have been. But there are still concerns over the safety of electronic throttle systems, which may have played a part in the cases of sudden unintended acceleration (SUA).
Last week, The Wall Street Journal that information held on data recorders from dozens of Toyotas involved in SUA incidents suggested that throttles had been fully open and brakes not applied at the time, according to an initial analysis by the US Department of Transportation (DOT). That would be consistent with drivers hitting the gas when they wanted to brake.
Electronic accelerators used by Toyota and other manufacturers have two independent sensors attached to identify the pedal position. An electronic fault affecting one sensor would cause a variation in voltage between the two, triggering a fail-safe mode that limits the vehicle鈥檚 speed. The DOT鈥檚 analysis 鈥� part of a wider SUA review 鈥� has analysed in-car recorders to see whether any voltage variations were detected.
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But the fault detection system is not foolproof, according to , a vehicle electronics researcher at Clemson University in Greenville, South Carolina. This month, Hubing told a US National Academy of Sciences committee investigating SUA that when his team fired radio waves at laboratory test vehicles travelling at a steady speed, they . These incidents were not picked up by the fault detection system, possibly because the radio waves affected both sensors equally, Hubing says.
鈥淐ars today are safer than they have ever been, largely due to the electronics,鈥� Hubing says. 鈥淗owever, there are still safety-critical systems in many vehicles that rely on information from sensors that are vulnerable to electromagnetic interference or electrical faults.鈥�
A spokesperson for Toyota said: 鈥淲e welcome the industry-wide review of electronic throttle control, and believe that by the end of the study consumers will have a better understanding of how it benefits them, and how safe and reliable it is.鈥�
The DOT review should show whether any vehicles involved in SUA incidents had their brakes engaged. But those results are not expected for months. Until then, it is premature to conclude that driver error is the sole cause of SUA.
