High Pitch Hissing/ Whining Noise Under Hood

[jawiv]

Anybody know what this noise is? Car is 2022 Mustang GT and the engine was off at the time of this video. Noticed this high pitch whining noise when I was washing the car. It has gone away now but seems like something electrical and sounds concerning.

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[ORRadtech]

It sounded more like a whistle to me. Made me think of an old fashioned tea kettle releasing steam.

It's so very hard to identify noises on an internet video...

 

[Unas2k5]

If the engine was off then that sound wasn’t coming from your car that’s why you don’t hear it anymore.

 

[luca1290]

If the engine was off then that sound wasn’t coming from your car that’s why you don’t hear it anymore.

That's poor advice.

OP, it's the voltage regulator, it's completely normal, don't worry.
The engine may be off, but the car surely isn't.

 

[jawiv]

Definitely was coming from the car and coming from that area under the hood.

Why would the voltage regulator be making that noise? I don’t think I’ve ever heard that noise before from the car.

 

[luca1290]

Why would the voltage regulator be making that noise? I don’t think I’ve ever heard that noise before from the car.

It is how a switching power supply works; it does by dividing the current into smaller "chunks" by cutting it with MOSFETs then leveling the output.
When they are new they make the same sound, just with a lower volume; when they age they can come a little "loose" and you hear the resonant frequencies better.

Even came near a big power supply and heard the 50Hz hum? This is the same, just at a different frequency.
It has no effect on performance or durability of the component.

 

[ORRadtech]

That's poor advice.

OP, it's the voltage regulator, it's completely normal, don't worry.
The engine may be off, but the car surely isn't.

It is how a switching power supply works; it does by dividing the current into smaller "chunks" by cutting it with MOSFETs then leveling the output.
When they are new they make the same sound, just with a lower volume; when they age they can come a little "loose" and you hear the resonant frequencies better.

Even came near a big power supply and heard the 50Hz hum? This is the same, just at a different frequency.
It has no effect on performance or durability of the component.

I'm sorry, I don't believe this. I've never heard a car do this. Even if what you say is true it is definitely not "normal", on or off.

 

[luca1290]

I'm sorry, I don't believe this. I've never heard a car do this. Even if what you say is true it is definitely not "normal", on or off.

it's explained here: power supply - What might be the cause of high pitch sound coming from a switching regulator circuit? - Electrical Engineering Stack Exchange

Just because you didn't hear it, that does not mean the phenomenon does not exist.
The OP can easily verify this: just turn on some electrical load and you'll see it changing frequency...
And yes, heard it on countless cars...

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