Fuel evaporation leakage check?

2007 prius, 158K miles, just had battery replaced. After a little research, I though perhaps that the sound my car makes after I've shut it off was this leakage check. However, it is doing it while I'm driving as well, repetitiously. This morning, I started timing it. 4 seconds off, 5 seconds on. Turned the car off, it was 8 seconds on and about 8 seconds off. Came back an hour later and it wasn't doing it until I started the car. Even does it while idling at stoplights. Love this car, wasn't ready to scrap it after the battery died, but this noise is truly annoying. It was doing the same thing before the battery was replaced, but I hadn't timed it.

Thanks in advance!

 

I think you're right, the break actuator. Just watched another video on youtube. Perhaps that would explain why sometimes the ABS VSC lights will sometimes come on when I first turn on the car.

The dealership told me it was the battery running a self test.

Ok, reading some more, sounds like this is a serious problem and another expensive fix. Motherchucker....And now I really hate this dealership. Should have just bought that new RAV4 I had my eye on, from someone else of course. Just makes me pause at the thought of buying another hybrid while I live here.