UPDATE: The U.S. National Highway Traffic Safety Administration has opened a formal inquiry into the brakes of the 2010 Toyota Prius hybrid. It has now received 124 complaints of faulty brakes, out of roughly 37,000 of the cars sold to date in the U.S.

Toyota said it would cooperate fully with the investigation, which applies only to the 2010 model-year Toyota Prius hybrid.

[Automotive News (subscription required)]


Yesterday, we reported that Japan's Department of Transportation had forced Toyota to investigate complaints about inconsistent braking behavior in its new 2010 Toyota Prius, the completely redesigned third generation of its signature hybrid.

Today, we learn that Toyota has admitted that early examples of the 2010 Prius--those built from the launch last spring until late January--had a software glitch in the redesigned electronic system that controls its anti-lock braking system.

The NHTSA has received more than 100 complaints about unusual brake pedal feel.  Drivers complain of loss of braking ability or slipping brakes, often on bumpy or icy roads. Fourteen drivers in Japan also identified the same behavior, all during winter months.

2010 Toyota Prius

2010 Toyota Prius

2010 Toyota Prius

2010 Toyota Prius

2010 Toyota Prius

2010 Toyota Prius

Pre-Production 2010 Toyota Prius in Orlando

Pre-Production 2010 Toyota Prius in Orlando

2010 Toyota Prius

2010 Toyota Prius

Grille - 2010 Toyota Prius 5dr HB II (Natl)

Grille - 2010 Toyota Prius 5dr HB II (Natl)

Anti-lock + regen + braking = confusion?

Toyota said it has identified a problem that occurs when the anti-lock braking system activates, to prevent the car from skidding, just as the 2010 Prius switches over from regenerative braking--which recharges its battery pack--to the conventional friction brakes.

Hiroyuki Yokoyama, the company's manager in charge of quality in Japan, told reporters Toyota had now found the problem, and that a fix (presumably a software patch) has been designed.

2010 Prius only, not earlier models

But he also said Toyota is still debating "what actions to take" for 2010 Prius models already on the road.

The problem is restricted to the third-generation 2010 Prius, introduced early last year. That car uses a redesigned control system that integrates anti-lock braking with the combination of its regenerative and conventional brakes.

The problem does not apply to either first-generation (2000-2003) or second-generation (2004-2009) Prius models.

What to do? Brake harder

If you experience any unusual braking behavior while driving a 2010 Toyota Prius--especially in conditions where the road is slippery or bumpy--Yokoyama said the solution is simple: Press harder on the brakes.

Drivers of 2010 Prius models who have experienced the braking issue say it can recur in those road conditions, so stay alert and be prepared to slam on the brakes if necessary. Don't worry about losing control; the anti-lock system will prevent the tires from losing traction.

Different from accelerator issues

This anti-lock braking issue in the 2010 Toyota Prius is a new and different problem from the two separate recalls of various Toyota and Lexus models that may experience sticking accelerator pedals. Toyota is now recalling more than 8 million cars on five continents to address that problem.

For full details on the two earlier Toyota recalls in North America (including certain Lexus and Pontiac models)--along with what to do if your accelerator sticks--visit our summary: Toyota And Lexus Recall: Everything You Need To Know.

Also different: Woz

The latest Prius anti-lock braking problem also seems to be separate from the problems experienced by Apple cofounder Steve Wozniak, aka Woz, in his new 2010 Toyota Prius.

He complained on Monday about sudden acceleration in that car, though he noted he was able to replicate the problem at will. It's possible that behavior may be related to the unusual control interface for the cruise-control system used by Toyota on its hybrids.

Toyota's shining star

The Prius midsize hatchback may be Toyota's most visible vehicle. It defines the company's achievement in developing hybrid-electric vehicles, of which it has sold more than 2 million globally since 1997--about two-thirds of all the hybrids in the world.

It is by far Toyota's highest-production hybrid, with about 1.2 million made over 14 years. Roughly half of those have been sold in the U.S., the world's largest market for hybrids, which now represent almost 3 percent of new car sales there.

As of 2009, the Prius was the third-best-selling car for Toyota in the U.S., following the midsize Camry and compact Corolla (though light trucks and crossovers are not included in those numbers).

[The New York Times]