noise in reverse

Your dealer is talking about the "spaceship" noise that is generated at low speeds in either direction. Does the "grinding noise" only occur when you engage the brakes? If so it is rust on the rotors and you can clean them by getting up to 25-30 MPH, putting your Prius in neutral (to shut off regenerative braking), and applying the brakes lightly. Repeat as required to eliminate the noise/rust.

JeffD

 

I'm pretty sure it's normal. Mine only happens in reverse, and it's not a grinding. It's more like a wet finger on crystal drone or a bad wheel bearing sound (if you've ever experienced that). You probably only noticed this, once you've turned-off that incessant reverse beeper and you have your windows rolled down.
If you had a real problem, the grinding sound would persist - moving forward or back. Since your issue is isolated to reverse, I doubt you have a problem. If you think I'm full of BS - Find someone else with a Prius and have them throw it in reverse. Unless they modified or clipped that external buzzer; It should sound similar.

Good Luck......

PS. It needs to be a 2017 or newer Prius. The older ones had something similar, but they sounded way different.

 

It's actually a speaker in the front. They had to add the speaker to make a noise when the car was moving for safety reasons.

 

ifit were the VPNS, it would make the same same forward or backward up to 15mph or so.

open the drivers window and listen in both directions with the engine off.

Electric_vehicle_warning_sounds

 

somewhere in the engine bay, there's at least one thread here somewhere

 

here's one:
2021-prius-disable-virtual-engine-sound-aka-spaceship-hum.221965

see post #38


and another:

vehicle-proximity-notification-system.163144

 

It’s not only on in reverse, it also sounds in drive when the gas engine is off up to 22 mph. It’s much louder in reverse so people behind the car can hear the sound, because the speaker is up front.

 

that's interesting, i had not read that before. makes sense though

 

LoL; I'm getting old and my hearing is going anyways. I had a service call today about an incessant hum - I couldn't hear it. So I unplugged the monitor, and she said it was still there. I unplugged the UPS, and she goes - it's gone, but can you do something about the alarm?
So I asked her, which is more annoying - the alarm or the hum. She says, well the alarm. Great!!! another satisfied customer!!!!
Actually, I told her it'll take me about a week to get you a new UPS.

 

Maybe the clutch? IIRC it need to disengage the drive train from the ICE for the car to be able to go backwards.

 

There is no clutch in a Prius (other than a "torque limiter")

JeffD

 

John Kelly, WeberAuto:
2016 - 2022 Prius, Prius Prime Transaxle - P610 Deep Dive (P710, P810 Similar)
Toyota - YouTube
starting at about 9 minutes into video.

 

aha

 

whoah.

I must have skipped over that part back when I watched the video. I'm still impressed that two rotors are turning up to 17,000 RPM in there.

 

Yes, new models are MUCH louder in reverse. Different sound, but nearly the same volume as an idling diesel truck. Seriously annoyingly loud.

As for Professor Kelly, his Prius videos should be required viewing for Prius owners.

 

A direct link to that P610 deep dive video makes it easier to see what part you're referring to.

At around 9 minutes, Prof. Kelly starts talking about what he calls the "clutch" damper, as you can see here. JeffD knows about that; it's what JeffD called the "torque limiter". Toyota's parts catalog calls it the transmission input damper assembly.



If you've looked at clutches before, you can see this looks a lot like a clutch pressure plate and clutch disc permanently assembled together, but with no means of releasing, ever. It has the coil springs that take up brief pulses in shaft torque, and it is able to slip slightly whenever there is torque that would exceed the mechanical limits, but that's all it does. All the rest of the time, it just rotates as one assembly; it does not act in any way as a clutch that can release. Every Prius has one of these.

A minute or so further into the video, Prof. Kelly discusses (but does not show) an additional "clutch" that only exists in the Prius Prime. The sprag clutch lives between the engine block and flywheel, and is simply a fixed type of one-way clutch that won't let the engine spin backward. It is needed in the Prime because the electric motors can drive the car forward at higher speeds, by pushing off against the engine crankshaft, which therefore has to be held against turning backward.



So in a Prius Prime, there are two kinds of clutch-like thing, but still nothing that ever disengages the engine from the drivetrain.