Question on a noise coming from engine bay

[Grantkat]

1999 S70 GLT.
When I turn the key to I, II, III there is a loud humming noise (sounds like a radio controlled small model plane) coming from right side of the engine bay (right as the driver sees it). I cant pinpoint it, however its somewhere below the alternator as best as i can tell. what might that be? and is that normal?

[wizechatmgr]

Any chance you can record the noise or post a video? This would be extremely helpful.

[scot850]

+1 on recording it. I can't think of anything electrical down there other than the alternator and AC compressor. An older turbo with a engine oil cooler thermostat can make a noise but the engine has to be running. When you say Pos I, II, III? III is when you start the car so the noise stays there when starting??

Otherwise I am stumped unless it is noise transfer from the ETM trying to self test?

Neil.

[Grantkat]

Here is a video

[Grantkat]

that video is with the key turned on but not started

[scot850]

You will need a stethoscope to try to isolate where that is coming from. I have no idea what could cause that issue. Does the car start and run ok?

Neil.

[Grantkat]

Car starts and runs perfectly. I will grab my stethoscope and try to figure out where that’s coming from

[Grantkat]

Ok here is more information. I have not quite figured out specifically what is causing the noise. However the noise is loudest when I place the stethoscope on the head light housing. I Place the scope everywhere i could reach, but the housing was the clear winner. I unplugged each light and all the lights at once including the turn signal and it did not make a difference. Im thinking i might remove the light house and see whats is what..

any ideas?

[rguzz]

Unplug the headlight wiper motor(s) and see if it goes away. When the motors go bad they usually buzz. I think it's a black plug(s). I will admit yours is pretty loud.

[Grantkat]

That was it!!! Thank you! Unplugged it, no noise, plugged back in and there it was!