New ISO standard may fix defects like Toyota’s

A new ISO standard currently under development creates a framework for ensuring the functional safety of electrical and electronic systems in motor vehicles. The development of ISO 26262 comes amid debate about the recall of more than 4 million Toyotas equipped with electronic throttles in which drivers experienced sudden rapid acceleration.

Toyota says – and the National Highway Transportation Administration concurs (NHTSA) – that the incidents of rapid acceleration are the result of floor mats being wedged against the accelerator and is recalling cars beginning next year to better tether the floor mats, shorten the accelerator pedal and add software that disengages the accelerator if the gas and brake pedals are pressed at the same time. But a major newspaper investigation points to defects in Toyota’s “drive-by-wire throttle” technology as a possible explanation for the malady.

The Los Angeles Times cited automotive experts skeptical that the steps taken by Toyota solve the real problem. “Many of these experts believe there may be a malfunction in the electronic engine control systems,” the Times reported Nov. 26.

As automobiles add more electronics the risk of electronic glitches grows “linearly,” said Poul Andersen, chairman of an electromagnetic compatibility standards committee of the Society of Automotive Engineers. Although not interviewed by the Times and not following the Toyota recall, Andersen was an electrical engineer at Chrysler for 34 years.

ISO standards affecting vehicle electronics include 7637, concerning management of electrical “transients” in an engine, and 11452, which establishes test procedures to see how well components in a modern car are insulated from interference in the MHz and GHz ranges.

“There are a tremendous number of low-transmitters operating in the GHz range and they are called cell phones,” he said, as an example

According to the SAE, 26262 is intended to replace a variety of existing ISO standards. A draft was approved in July and a final version is expected to be enacted sometime in 2011.

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