2021 Prius - Disable Virtual Engine Sound - AKA Spaceship hum

lol...that's one way! Of course it would ruin it and you would, still, have to remove it (don't want that stuff on the radiator!) When I hit a deer, it was one of the things they replaced "Pedestrian Speaker" which is $118 MSRP. I know for a fact nothing was wrong with it but I didn't see the inventory until after I got the car back (USAA paid for it minus my deductible.)

 

This is why used 2019's are worth more!

 

The speaker is located under the hood. It is very close to the front bumper on the driver's side. If you pop the hood and stand in front of the vehicle, then there is one piece of plastic paneling between you and the speaker. I have highlighted the piece in yellow in this picture. The red circles indicate the plastic pins adhering the trim to the body of the vehicle. To remove them, you need to pull up on the center piece of the pin (use a small screwdriver or some angled tweezers) to remove it and then you can remove the outer piece.

PRIUS SPEAKER Highlighted And Circled Trim Piece by Justice Guyoono posted Jan 16, 2023 at 8:07 PM

After you have removed the panel, you can see the speaker. It is circled here in red and is held on with one 12mm bolt.

PRIUS SPEAKER Exact Speaker Location by Justice Guyoono posted Jan 16, 2023 at 8:07 PM

First I just unplugged the speaker, then turned the car on and put it in reverse. I did not get the UFO noise but I did get a beep and an error message on my dash. This is because the Prius detects that the speaker is missing. It sends current to the speaker and hears nothing back, so it tells you to go to the dealer. I did not take a picture of the error message.

I was able to trick the Prius into thinking that the speaker was still plugged in by putting a paperclip in the female end of the connector. I then wrapped the connector with the paperclip in electrical tape and was able to drive silently without a hum or an error message.

PRIUS SPEAKER Paperclip Bypass by Justice Guyoono posted Jan 16, 2023 at 8:07 PM

However, this left me with some pause. First of all, the speaker was just sitting on a bench in my garage where it would surely get lost if I ever needed it again. Secondly, I had this connector just dangling there in front of the radiator, and if I pulled on it I could make it touch the radiator. I didn't really want electrical tape burning under my hood while driving around, so I undid my work and looked for a better solution.

The computer sends an electrical current to the speaker. The speaker makes some noise and sends some amount of electrical current back to the computer. This is how the computer knows that the speaker is still installed. The electrical current from the computer to the speaker follows the rules of all electrical currents - it takes the path of least resistance. If you can provide a lower-resistance path for the current to take, it will ignore all the internals of the speaker and take your path instead, leaving the speaker sitting in silence and the computer none the wiser. You could splice a new wire between the two that go to the speaker, but that is a pretty permanent solution for something that you or a subsequent owner might want to undo in the future. You could open the speaker up and short the circuit, but in addition to the previous point, the speaker's plastic housing is very fragile and I broke two clips while trying (unsuccessfully) to disassemble it.

I decided to provide a lower-resistance current by putting a piece of foil in the speaker-side of the connection. The way the connector is designed makes this really easy to do. Just place the foil roughly flat over the prongs and slide in the connector. With one piece of foil, I significantly reduced the volume of the sound. With three pieces, it was barely audible. Some current must have still been making it through since aluminum foil isn't the most conductive thing on the planet.

PRIUS SPEAKER Foil Bypass by Justice Guyoono posted Jan 16, 2023 at 8:07 PM

I still wanted it quieter, so I opted to find something more conductive than aluminum. I had some spare 22AWG stranded wire lying around, so I cut off a chunk, stripped it, and shoved it in the connector. It took a couple tries of progressively adding more and more loose strands to the connector, but eventually I got the speaker to be completely silent.

PRIUS SPEAKER Wire Bypass by Justice Guyoono posted Jan 16, 2023 at 8:07 PM

With this system, I am able to keep the speaker physically installed and connected, without any ugly or permanent modifications, and I don't have to hear the annoying UFO sound. If I see any blind people I will hold down my horn to replicate the effect for them.

I hope this helps somebody.

 

This is a great write-up with great pics. Thank you.

You need to be careful here though. The output to the speaker will expect a certain resistance to limit the current flowing out of the controller and through the cables. Without that resistance you risk damaging either the controller, overheating the wires, or heating up the foil to dangerous temperatures. Just in the same way as if you put some foil in the socket for a bulb in your house and switched it on, that would likely trip a breaker, blow a fuse, set fire to the cables, or melt the fixture.

If you have a multimeter, you can measure the resistance across the terminals of the speaker to find out what it is. They're usually a few ohms, e.g. 4 ohms or 8 ohms. Ideally you would need a suitable resistor of a suitable wattage to handle the current, connect that to the end of the cable, and wiretie the connector to something safe so it doesn't end up going into the fan.