Moaning/Whining noise?

I hear ya. My tech was thinking it could be related to disconnecting battery and engine ecu?

I'll just turn up the radio....and I can't hear it over 25 as the road noise takes over. It's just a subtle low hum.

 

Update :

The noise has been getting progressively worse, so back to the dealership today.

Results:
Two of the pulleys are loose/bad and are being replaced under my Toyota Platinum Extended Warranty. Toyota recommended replacing a couple other related parts (plates or something). Parts should arrive tomorrow, so they left it apart. I decided it made sense to also replace the serpentine belt at the same time.

They put me in a rental for the night/tomorrow...Nissan Sentry. Feels like my ass is going to drag on the pavement.

 

Picked up truck yesterday afternoon after work.....noise is gone and all is back to normal. Hopefully good to go for another 75,000+ miles with new belt. Not sure what the normal replacement interval is for that.