Professor David W. Gilbert’s work has been the basis of doubts about Toyota’s mechanical fixes.
Toyota disputes specialist who faults electronics
Company says experiment didn’t mimic driving
Toyota’s prime target was a Southern Illinois University engineering professor, David Gilbert, who testified before a congressional panel last month and appeared on an ABC News report showing how he short-circuited the electronic acceleration system in a Toyota Avalon to create runaway acceleration, and suggested such an event could happen under normal driving conditions.
Yesterday, Toyota held an elaborate news conference at its North America headquarters in Torrance, Calif., and presented company officials, engineers from an outside firm, and a Stanford University engineering professor. It dramatically replicated Gilbert’s experiment on several vehicles made by rival automakers that had been parked in the briefing room.
“We did what Dr. Gilbert and ABC should have done to test the real-world relevance of Dr. Gilbert’s findings,’’ said Toyota spokesman Mike Michels. Gilbert’s experiment was “completely unrealistic. He rewired and reengineered a vehicle in multiple ways in a specific sequence that is impossible to occur.’’
The criticism was echoed by Christian Gerdes, associate professor of mechanical engineering at Stanford and director of the school’s Center for Automotive Research, which is funded with money from Toyota and several other automakers.
Toyotas, like all modern vehicles, use an electronic linkage between the gas pedal and the engine, not a mechanical one, as older vehicles did. In his experiment, Gilbert tapped some of the six wires that send signals to the engine when a driver steps on the gas pedal and bridged the wires to create a short circuit. Then, he applied a small voltage that caused the engine on his test vehicle to race, causing sudden acceleration.
Gilbert noted that the Toyota’s engine computer did not diagnose the short circuit as a problem or issue an error message. Because the situation did not produce an error message, the vehicle’s fail-safe system - which is designed to cut engine power in such a situation - did not engage.
Though careful not to personally attack Gilbert, Toyota and its consultants argued that engineers can rewire and reengineer anything to make it fail. “We could rewire this building and cause it to go into flames,’’ said Subodh Medhekar, principal engineer with Exponent, the outside company Toyota has hired to diagnose the runaway acceleration problem.
Toyota also used Gilbert’s technique to short-circuit several non-Toyotas and achieved the same result - a racing engine. In the large room where yesterday’s briefing was held, Toyota displayed a
In an e-mail, Gilbert wrote: “Over the next several days, I will examine their expanded results and conclusions along with my own.’’