Strange noise coming from the front

Yes. It is a brake booster. Conventional cars use ICE power for this. Since HV/EVs don't often use ICE, a different system must do this.

 

Sure you aren't talking about the sound coming from the front left side speaker attached to the radiator that sounds like a grinding sound to alert pedestrians that you are a moving vehicle at speeds below 15mph in electric mode. The guy from Weber on youtube pointed it out on a breakdown of the 4th generation eco that he had torn down. Apparently going to be a government requirement soon here in the States.

 

My Prime, for the first time ever that I know of, was found making a very loud electric motor whirring sound, two hours after I was done driving it. Loud, like I could hear it more than a hundred feet away loud. Yes, the car was off. Not the brake accumulator sound. That I noise know of well, as this is my second Prii, third if you count my wife's. Absolutely don't know what the heck was going on. Somewhere in the front engine area is all I could narrow it down to. The ICE was never on during the drive home the two hours before. 40 degrees F. I went and got the key, walked up to it and opened the door. At the beep when you touch the door handle, the sound abruptly stopped. I went outside twice that night to see if it was happening again, and it wasn't. Puzzled.

 

Sounds like the A/C Hold button was pushed on then key fob?

 

I didn't push any buttons on the fob. The noise was going on without any fob in hand. In fact, the fob was 20+ feet away from the car when I noticed the noise on a quick trip outside 2 hours after I shut the car off. And it was off.

I then went back inside to get the fob to unlock the car. I never use the button on the fob to unlock the car. I touch the handle instead. That's when the whirring sound stopped.

The Gen3 would sometimes make the brake actuator noise a long time following shutdown. Those times were creepy. Most often the actuator sound with the click(s) was just a minute or two following turning the car off.

With the other things some people are reporting about their Primes, such as constant display reboots and ICE starting in warm weather at near full battery levels and little to no A/C, I count myself lucky so far not having those situations come up. I'll take this occasional (or once that I know of) weirdism as a curious but non-serious event.

 

Was it doing a charge session with climate prep enabled? I ask because this is very similar to what mine sounds like when I've pressed the key fob 10 minute duration climate prep. It shuts off when I open the door. It's the only thing I can think of that's similar sounding to your description. Yes, it's the loudest noise the car makes outside of driving with the ICE on.

I've been listening to all those other funky garage hybrid sounds on my 2010 & 2017 Prii and our 2014 Camry Hybrid for years. Like you say, they aren't even close to your description. That's why I mentioned the climate prep.

 

^ No charging that night. It was just a lonely Prime sitting in the driveway on a cold dark night. I'm beyond worrying about what it might have been at this point. If it happens again, I'm grabbing not just the fob but also my camera and will try to get a video with sound. I'm not saying aliens, but... aliens!

 

You described exactly what it sounds like when the HVAC is on via climate prep or remote AC. Maybe it got pushed by accident or maybe it was the traction battery cooler.

 

Does the HVAC stay on for two hours after it was accidently pressed? Doubt it was the cooler, as the 1.5 mile drive home at 40 degrees shouldn't have heated it up. Still a mystery.

 

I had a similar noise coming from the front left when i apply the brakes and slow to a stop like a tick tick tick or something hitting something, like the noise the spinner makes on the game of life. I took it to the dealer today and the front axle has to be replaced. If you hear this noise it is not normal. my Prime Advanced has almost 14k miles on it.