Noise Filter & Humming Sound from Rear Underside of Vehicle (1 Viewer)

[snowcruiser]

Ok, so I walked past my parent's parked 2011 GX460 the other night and heard a humming sound coming from the underside rear of the vehicle, behind the rear wheels. Vehicle was parked and had been turned off for several hours and key was in the house, not the vehicle. There sound reminded me of a running fuel pump or an antenna motor. Anyway, I pulled all of the fuel pump related fuses and relays and sound continues. Finally I pulled a large white fuse from the under hind fuse box labeled "Noise Filter" and the humming sound immediately stopped. The noise did not start again when I put the fuse back in its place.

So has anyone else experienced this? What exactly is the "noise filter" and is this normal behavior or is there an issue that needs to be addressed?

I'm concerned that whatever was running could at the very least drain the battery leaving them stuck somewhere...

Thoughts?

 

[cyclist85]

A couple of weeks ago my I heard a noise similar to what you are describing in my 2011 GX460. I had the same concerns about draining the battery. I was able to get it to turn off by turning on the ignition and then turning it off. After a bit of research I was able to find a link to a post on Club Lexus through gxor.com: Noise from under vehicle after turning off the engine after 5 hours. In the post was the following excerpt from the owners manual.

"Noise from under vehicle after turning off the engine: Approximately five hours after the engine is turned off, you may hear sound coming from under the vehicle for several minutes. This is the sound of a fuel evaporation leakage check and, it does not indicate a malfunction"

It seemed to me this was the cause and there was not any reason for concern. I did not do the troubleshooting you did with the fuses, but the same fuse you are referencing also controls the coil, injector and ignition. However, I am not sure what the noise filter is in conjunction with this fuse. I know noise filters are sometimes used in conjunction with the radio.

 

[snowcruiser]

Thanks Cyclist. Your research is helpful and I won't worry about it now. Cheers