One problem related to brake master cylinder has been reported for the 2007 Toyota Prius. The most recently reported issues are listed below.
While backing out of my parking space at work, my brakes went to the floor and barely stopped the vehicle. Alarm was going off, so I pulled forward just enough to see if the brakes were working at all and they were probably 98% gone. I parked, got towed to dealer near my home with aaa. I later found out that a pair of abs skid control relays (2 88263-21010) caused the problem. Nothing mechanical failed. These relays caused my entire braking ability to be lost. I believe this is an unsafe design as there is no mechanical connection available at the pedal if you have this electrical problem. Some mechanical brakes should be available. The emergency brake is on / off only and no in between. I would like to find what legal remedies are available to me as I am considering changing to a safer vehicle due to this design flaw. As in power brakes, if you lose the power brakes, you can still stop the vehicle, though difficult since there is still a mechanical hydraulic system in place even with a failed power booster. The consumer also stated the master cylinder failed. Updated.