Sound when accelerating the first time after a start

We'd need a recording of the sound in order to identify it. The Prius makes a lot of noises, some strange to the first time owner.

 

Mine has done it since new. I think there's some thread somewhere that addresses it. Try searching...

 

sounds like a sticky suspension bit or brake caliper. i get a good creeping noise every time i back out of my driveway and the car is between the angled driveway and the flat street. happens the first time of the day only.

 

Mine makes a thud when pulling out of my parking spot on first drive in the morning also. I figured it was either suspension related or brake related due to rust overnight. Nothing to be worried about.

 

The rotors will look rusty - because you don't use the brakes a lot of the time, so aren't wearing the rust off every time you press the brakes. Don't worry about them, the brakes will last 4, maybe 6 times longer than in a "normal" car.

 

is it the auto door locks?

 

Yeah, might be auto door locks. Manually lock doors before taking off to see if it eliminates it as a suspect.

 

not the pedestrian warning system?

 

it is an electronic kind of whirring sound. if you roll the drivers window down, and drive slowly in ev only inside a garage or similar, you can hear it. the speaker is in front of the drivers side wheel.

you can also find you tube demonstrations. i believe gen 4 allows you to set volume levels.

VPNS: vehicle proximity notification system, it should be in your manual.

there is a thread here on disabling: in the 'gen 4 prius accessories and modifications forum'

search 'Vehicle Proximity Notification System' by member randomwalk101

 

sounds like two separate sounds in your recording, one right after the other

 

Are you sure it's not the brake test. It makes a single soft squick noise around that speed

"When the vehicle speed reaches approximately 20 km/h (12 mph), the initial check of the brake actuator assembly is performed and pump motor operation sounds are generated"

Posted via the PriusChat mobile app.

 

I experience something like this and it sounds like a belt slipping once. Sort of like a cross between a chirp and a zipping sound, as if a belt slipped for a moment and then caught. Definitely not a screeching sound like old-school belts truly slipping. Maybe something like a long zip tie being tightened rapidly.

 

It’s the brake test, as @GRich kindly mentions above; mine does it too, and it sounds just as you describe. The car has no belts, since the air conditioning compressor, water pumps, etc., have to be able to operate when the gasoline engine is stopped.