Japanese Transportation Ministry Orders Investigation Into Toyota Prius Braking Issue

By Eric Loveday

Eric Loveday

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Eric Loveday is a car enthusiast with a love for everything automotive. He purchased a 1970 Chevelle at age 16, quickly outgrew its dated engineering... More

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1,209 views Feb 7, 2010

2010 Toyota Prius rolls onto the Detroit stage at its global debut in January 2009

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The Toyota recalls have made headline stories for at least a week now.  The company is working feverishly to fix the problems and rebuild a possibly tarnished image.  Just when things could not possibly get any worst for Toyota, they just did.

According to the New York Times, the Japanese government has ordered the company to investigate a possible defect in regards to the Toyota Prius.  The focus of the investigation regards the braking system of the vehicle.  Complaints have come in from many Prius owners stating that the brakes have stopped working momentarily at low speeds while driving on rough or slippery roads.

As Kenji Sato, a transport ministry official in charge of recall policy for Japan said, "The drivers have complained that the brakes on their Priuses have momentarily stopped working when driving at low speeds, especially on slippery surfaces."

Back in July of 2009, a Prius collided with a stopped vehicle at an intersection in Japan which injured two people.  The brakes were the likely culprit.  Additional complaints were filed by Prius drivers in Japan during the month of January which leads to the speculation that slippery surfaces may affect the braking system.

In the U.S., the NHTSA has logged 136 complaints in regards to the braking system of the 2010 Prius.  The recurring them amongst the complaints is the feeling that the vehicle either surged forward or temporarily lost braking power after encountering rough road surfaces.

Toyota acknowledges receiving complains about the braking system.  Toyota spokesman Takanori Yokoi said that he was contacted by dealers in both the U.S. and Japan who had stated that the Prius  occasionally "brake insufficiently" during certain situations.

Is this another potential problem for Toyota?  It seems likely that the company will have to react to this situation also.  However, the likely cause of the problem can be attributed to the hybrids complex braking system which changes between regenerative braking (strong braking used to charge the batter) and friction braking (normal brake system).  When the changeover occurs, drivers may experience what feels like acceleration when actually it is a lessened degree of deceleration as the friction brakes go into action.  This could however cause drivers to overshoot their expected stopping point.

We will keep you updated on this story as more information becomes available.

Source:  New York Times