Toyota is blaming the software in the Prius braking problem they are having. Keep in mind, this is separate from the massive recall on other Toyota cars.
The 2010 Toyota Prius is likely to face a recall after Toyota admitted (Source: CNN.com to a software glitch in the Prius anti-lock brake system.
According to the story, Toyota has already fixed the problem in cars that are being manufactured now. They just haven't provided any communication to owners.
The 'disconnect' causes a less than one second delay before the brakes take hold. Customers have described the problem as occurring when they are on frozen or bumpy roads, and I've seen some descriptions as indicating it takes a moment for the car to switch from regenerative braking to friction braking.
Over a dozen complaints have been lodged in Japan, while over 100 have occurred in the US.
A search of NHTSA's complaint database turned up ...The 'jerking forward' seems to be lack of slowing down, rather than actual acceleration. But that still has to be a scary thing when driving in conditions that are already rough (icy or bumpy).
"I have been driving my 2010 Prius for 6 months and have experienced the following nearly 10 times," one owner wrote. "When braking, if a pothole or bump in the road is hit, the car seemingly jerks forward/accelerates for a split second."
This issue does not seem to be affecting earlier generations of Prius, just the new 2010 model.
UPDATE: The NHTSA has opened a formal investigation and Toyota has released a statement:
Toyota is aware of NHTSA’s intention to begin a Preliminary Evaluation centered on owner complaints of a braking issue with the 2010 model year Prius. Toyota will cooperate fully with NHTSA’s investigation.
Some customers have complained of inconsistent brake feel during slow and steady application of brakes on rough or slick road surfaces when the anti-lock brake system (ABS) is activated in an effort to maintain tire traction. The system, in normal operation, engages and disengages rapidly (many times per second) as the control system senses and reacts to tire slippage. A running production change was introduced last month, improving the ABS system's response time, as well as the system's overall sensitivity to tire slippage.
This preliminary evaluation addresses owner complaints specific to the 2010 Prius. This condition is not related to either the floor mat entrapment recall or the sticky pedal recall currently in action.
Toyota will continue to evaluate the condition as it relates to owner complaints and will keep NHTSA informed of its progress.