folks, My 2005 Gen II just did something odd. I drove it about 8 miles to the zoo and parked it for 4 hours. When I got in, that brake pressurizing buzz sounded. Startled the bejeebers out of me as I don't ever remember hearing it when I get IN the car. No warning lights, but when I turned the car on, the battery was on two red bars. The car drove fine on the way home. When I parked it at home, the pressurizing buzz came on as I was getting out. Normal, right? But then it cycled on and off about 7 times. Never heard that before. I had to go inside before I could see if it stopped on its own but I went back about 15 mins later and stood there listening. Nothing. So I got in and pressed on the brake pedal w/o turning the car on, and yep - same noise. Still no warning lights. Is this normal and I've just never noticed it before, or is something going wonky? Thanks in advance! Kary
The "cycling on and off about 7 times" part is wonky. Otherwise, yes, the brake pressure pump can turn on when the driver's door is opened, but not always.
It could be time for a brake bleeding. This is something that most people have the dealer do, although most mechanics can do this, if careful and well informed. Bleeding 05 Prius brakes the old fashion way | PriusChat
FYI, it hasn't done it again. This happened immediately after a 5-day sojourn above 6,000 feet (I live at sea level) with 20F temps at night. No clue if that might have affected anything.