Toyota shares finding in runaway Prius investigation, refutes claims

Mar 15, 2010 5:40 PM

Toyota held a press conference this afternoon to share the preliminary findings of its investigation in the runaway 2008 Prius event in the San Diego area last week.

According to a Toyota press release, the investigation yielded these preliminary findings:

A Toyota carpeted floor mat of the correct type for the vehicle was installed but not secured to the retention hooks. It was not found to be interfering or even touching the accelerator pedal.
The front brakes showed severe wear and damage from overheating. The rear brakes and parking brake were in good condition and functional.
The accelerator pedal was tested and found to be working normally with no mechanical binding or friction. It should be noted that the Prius is not subject to a recall for sticking accelerator pedals and the Prius component is made by a different supplier than the one recalled.
The pushbutton power switch worked normally and shut the vehicle off when depressed for 3 seconds as the 911 operator advised Mr. Sikes to do.

The shift lever also worked normally and neutral could be selected. The neutral position is clearly marked and can be easily engaged by moving the lever left to the "N" marking.

There were no diagnostic trouble codes found in the power management computer, nor was the dashboard malfunction indicator light activated. The hybrid self-diagnostic system did show evidence of numerous, rapidly repeated on-and- off applications of both the accelerator and the brake pedals.

After examination of individual components, the front brakes were replaced and the vehicle was test driven, during which the vehicle was observed to be functioning normally.

During testing, the brakes were purposely abused by continuous light application in order to overheat them. The vehicle could be safely stopped by means of the brake pedal, even when overheated.

The Prius braking system uses both conventional hydraulic friction brakes and a regenerative braking system, which switches the electric drive motors into brakes to generate electricity.

The system features a sophisticated self-protection function which cuts engine power if moderate brake pedal pressure is applied and the accelerator pedal is depressed more than approximately 50 percent, in effect providing a form of "brake override."

This function, which is intended to protect the system from overload and possible damage, was found to be functioning normally during the preliminary field examination.

Toyota engineers believe that it would be extremely difficult for the Prius to be driven at a continuous high speed with more than light brake-pedal pressure, and that the assertion that the vehicle could not be stopped with the brakes is fundamentally inconsistent with basic vehicle design and the investigation observations.

These findings suggest that there should be further examination of Mr. Sikes account of the events of March 8.

NHTSA investigators were present during Toyota's examination, and are conducting their own investigation of the vehicle and its performance. Toyota's examination was also observed by a congressional staff member.

Earlier today, National Highway Traffic Safety Administration (NHTSA) released a statement on its ongoing investigation. NHTSA stated, "So far, we have not been able to find anything to explain the incident that Mr. Sikes reported."

Read: "More questions raised on Toyota Prius sudden acceleration cases."

—Eric Evarts

Be sure to follow Consumer Reports Cars blog (RSS) and Twitter (@CRcars) to keep up with the latest information and advice, also see our unintended acceleration guide.

More About: Cars | Safety | Toyota | All Cars News

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