As expected, Toyota has announced a recall for its 2010 Toyota Prius and 2010 Lexus HS 250h models to update the anti-lock braking system (ABS) software. The new software improves the response time of the anti-lock system and alters its sensitivity to tire slippage.

The update is intended to reduce inconsistencies in brake feel that many owners experienced as brake failure. The recall is voluntary, meaning that owners need not have their cars updated if they are satisfied with the brake feel.

2010 Toyota Prius

2010 Toyota Prius

Lexus HS250h

Lexus HS250h

2010 Lexus HS250h - rear

2010 Lexus HS250h - rear

Interaction of ABS, regen & hydraulic brakes

In the 2010 Toyota Prius, the problem occurs when drivers apply the brakes steadily on slick or bumpy road surfaces, causing the ABS to activate just as the car switches from regenerative braking to conventional hydraulic brakes.

As reported earlier, Toyota has already incorporated the updated software into 2010 Prius models built starting late last month.

About 133,000 2010 Prius vehicles built from May 2009 through January 2010 will be recalled. The recall does not apply to earlier Prius models, built from 2000 to 2009, which used a different anti-lock braking system.

2010 Lexus HS 250h too

The recall also includes all models of the 2010 Lexus HS 250h, the new dedicated hybrid sedan from Toyota's luxury brand, in which drivers may experience the same inconsistent brake feel. The new software will be added to HS 250h models starting later this month.

Toyota plans to mail letters to Prius owners starting next week, and HS 250h owners "within the next few weeks," to let them know they can bring their vehicles to a local dealer. About 14,500 HS 250h models are affected.

The recall extends beyond North America: Toyota announced a recall in Japan for the same issue early yesterday, and globally, about 437,000 Prius models will be eligible for the update.

Toyota acceleration issue: separate

The ABS update recall for the 2010 Toyota Prius and 2010 Lexus HS 250h is separate and unrelated to the two separate recalls of various Toyota and Lexus models to address potentially sticking accelerator pedals.

Those fixes included replacing and securing floor mats, shortening accelerator pedals, and installing brake override software on more than 8 million vehicles globally.

Visit our summary, Toyota And Lexus Recall: Everything You Need To Know, to get full details on those two earlier recalls in North America. The article also includes what to do if your accelerator pedal sticks.