OT+ electric motor or pump running while vehicle is off

[Pottsy]

Two different times I walked into my garage at night to hear a pretty loud electric pump/motor type sound. The first time I was so confused where it could be coming from, not thinking my GX since it was obviously off, but then realized its coming from under the GX. Seems to be coming from a component near the middle to the back of the underbody. I chalked up the first incident to a fluke, but it has since happened again and I am concerned.

It's clearly something electric running when the ignition is completely off/vehicle locked. I am worried I am going to walk out to a dead battery now after hearing it for a second time. Opening the car doors, locking/unlocking, and turning on the ACC but not the engine do NOT get it stop. The only thing that has stopped it was to start the engine and then shut it down. My first thought was it sounds like an electric fuel pump kicking on or something. But obviously not something that should be happening when the vehicle is off.

I attached a short video of me under the GX trying to capture the sound. You can't see anything in the video but you can hear the sound it's making. I am hesitant to just take in for service since it's only happened twice and randomly and I am not sure how they would even diagnose the issue. Has anyone else encountered this?

Appreciate any input.

 

[teestarnes]

Coincidentally I came to this forum to post the exact same question. Was just in my garage and took a nearly identical video before I saw yours. I have no idea what it could be but seems to be coming from near the rear axle. I turned the car electrical on by pressing the start button without foot on brake, then off, and the noise stopped. Would love to know if this is something I should add to my list of things to ask about at my first service interval, or if it's expected/normal.

 

[Toxicdog]

It is an emissions/gas vapor pump leak check. This has been around for awhile with the other models.

 

[teestarnes]

Got it, thanks for clarifying! Did find this thread using your keywords @Toxicdog

Fuel pump buzz/noise? - ClubLexus - Lexus Forum Discussion

 

[Pottsy]

Super helpful, thanks for the details. This is the first car I have owned with such a system and haven't gotten to that part of the manual yet I guess . Appreciate the info. Next time I'll just crack a beer and see how long it runs for just out of curiosity.