'15 CX-9 High-Pitch Whine From Engine on Accessory Key Cycle

Hi, all!

We recently discovered a strange issue with our '15 CX-9 with 85k miles. Upon cycling the key into the accessory position, a loud, high-pitch whine is emitted from the engine bay. See attached video:

'15 CX-9 Whine

It will continue until the key is removed or the engine is started. It DOES go away if the gas pedal is depressed (engine still off). We have narrowed the position of the noise down to the lower driver's side (USA) of the engine bay. It can be heard clearly in the cabin, especially with the windows down.

Any ideas as to what this could be? It has never been an issue before this week... thank you!
2010 CX-9 GT
Any warning lights or codes?

In that area of the firewall, there are a couple of fuse boxes, an evaporative emissions valve, and I think the ABS pump. It sounds like a buzzing relay or solenoid. You could open the fuse box and feel the relays to see if any are vibrating. If that isn't it you could start pulling fuses and see if you can isolate what circuit is powering the buzzing.