Faulty electronically controlled throttles may be responsible for some of the reported ‘sudden acceleration’ incidents involving Toyota and Lexus vehicles in the United States, according to a weekend newspaper report.
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The Los Angeles Times (LAT) said data pointed to Toyota’s throttles rather than the ‘floor mat entrapment’ and accelerator pedal shape the automaker cited in last week’s announcement that it would recall and modify around 4.2m vehicles in the US. Some models will also get a software update that cuts the engine if both the accelerator and brake pedals are pressed simultaneously.
Toyota said the accelerator pedal design makes it vulnerable to being trapped open by the floor mat.
But accounts from Toyota owners, interviews with auto safety experts and a review of thousands of federal traffic safety incident reports all pointed to another potential cause: the electronic throttles that replaced mechanical systems in recent years, the LAT said in a special report.
The paper said complaints of sudden acceleration in many Toyota and Lexus vehicles “shot up almost immediately after the automaker adopted the so-called drive-by-wire system over the last decade”.
For some Toyota models, reports of unintended acceleration increased more than fivefold after drive-by-wire systems were adopted, according to the LAT’s review of complaints filed with the National Highway Traffic Safety Administration (NHTSA).
The LA Times said Toyota first used electronic throttles in 2002 model year Lexus ES and Camry sedans and the paper had found that total complaints of sudden acceleration for the Lexus and Camry in the 2002-04 model years averaged 132 a year, up from an average of 26 annually for the 1999-2001 models.
The average number of sudden-acceleration complaints involving the Tacoma mid-size pickup truck jumped more than 20 times, on average, in the three years after Toyota’s introduction of drive-by-wire in thosse trucks in 2005. Increases were also found on the hybrid Prius, among other models, the LAT said.
Toyota spokesman Brian Lyons was quoted as saying the automaker could not explain the trend and the LAT noted that Toyota had consistently maintained that electronic control systems, including drive-by-wire, were not to blame.
“Six times in the past six years NHTSA has undertaken an exhaustive review of allegations of unintended acceleration on Toyota and Lexus vehicles,” Toyota said in a statement this month. “Six times the agency closed the investigation without finding any electronic engine control system malfunction to be the cause of unintended acceleration.”
In addition, the paper said, NHTSA officials have consistently said they have not found any electronic defects.
The acceleration problem with Toyota and Lexus vehicles came sharply into focus recently after San Diego highway patrolman Mark Saylor, his wife, daughter and a family friend died in the fiery 100mph crash of a dealer-owned Lexus ES350 ‘loaner car’ last August. The man’s desperate efforts to stop the car were recorded on a 911 emergency call made by a passenger.
After that incident, The Times reported that sudden-acceleration events involving Toyota vehicles had resulted in at least 19 deaths since the introduction of the 2002 model year. By comparison, NHTSA said all other automakers combined had 11 fatalities related to sudden acceleration in the same period.
The Times subsequently reported that the law firm of McCuneWright had filed a national class action lawsuit against Toyota Motor Corporation on behalf of US Toyota and Lexus owners who had ‘experienced incidents of sudden unintended acceleration’.
Independent electronics and engineering experts told the paper that the drive-by-wire systems differ from automaker to automaker and that the potential for electronic throttle control systems to malfunction may have been dismissed too quickly by both Toyota and federal safety officials.
Electronic throttles are vulnerable to software glitches, manufacturing defects and electronic interference that could cause sudden acceleration, they said, according to the report.
Although Toyota has said it knew of no electronic defects that would cause a vehicle to surge out of control, it had issued at least three technical service bulletins to dealers warning of problems with the new electronic throttles in the 2002 and 2003 Camry, the LA Times said.
The throttle systems on six-cylinder engines can cause the vehicle to “exhibit a surging during light throttle input at speeds between 38 mph and 42 mph,” according to one of the bulletins that was published by vehicle information company Alldata. The solution provided to dealers was to reprogramme the engine control module, the paper added.
According to the report, NHTSA has conducted a total of eight investigations of unintended acceleration in Toyota vehicles since 2003, prompted by defect petitions from motorists and its own examination of complaints. But the agency has tested electronic throttle systems only twice in those probes, its records showed.
