The National Highway Traffic Safety Administration told The Associated Press it has received 124 reports from consumers, including four reports of crashes. The investigation will look into allegations of momentary loss of braking capability while traveling over uneven road surfaces, potholes or bumps.
The Japanese government has ordered Toyota to investigate brake problems. The automaker said it had corrected problems with the antilock brake system in Prius models sold since late last month, including those shipped overseas.
The flaw requires a software programming change to fix.