2010 F150 on & off whining noise around the engine.

The internal regulator is electronic, it would not whine. A bearing would cause it to whine in the alternator. I usually associate a whine as coming from the power steering pump. Try this. Start the vehicle and slowly turn the wheel from left to right. See if the while comes and goes.

Thanks for the answers! I'm pretty sure it's not the steering pump. But I will try testing it. The thing that Stumped me was while it was whining/humming, I definitely heard a CLICK, and it instantly stopped making the noise! I've never ran into to this weird one. I'm an Old hot rodder.

Thanks Ed! - Will do. Good to have knowledgeable people out there to help each other out!

Well, the whining had continued on & off. Yesterday the battery was too low to start her truck. So.... After jump starting it, I check the battery voltage with it running. 14.54 V. Unhooked the battery & did a load test on it. It went fairly low, but passed. So I took an estimated guess & replaced the alternator with a re-manufactured one. (Expensive) Following all the normal guidelines. Unhooked battery terminals, cleaned them, Battery is up. Well now.... I start it up, everything looks good. I check the battery voltage at an idle. & it's 13.48 V. And I'm going, well that's lower than I would suspect, but it should be ok. Then I get in the pickup and the battery symbol & chime is going off. What the Cuss! So I go to town & we put a brand new battery in it. No change. Still around 13.40 volts. SO my question now is the computer looking for 14+ volts?? Is that why the warning is going off now. I told the parts store & they are getting me another reman, like I just put on it. Well see if it charges more. Curious about why the warning & chime is going off now. Geezz! Thanks.

Hi. For everyone's information, I changed the alternator with a re-man. & changed the pig tail connector to the alt. Something worse happened. Since the alt. is controlled by the PCM, something happened and the PCM went into limp mode. Charging a steady 13.4V, Dash alarm going off. I had did everything right when changing the alt. Battery charged & disconnected. cleaned all the terminals, etc. I ended up taking the pickup to Ford. We put a new battery in it. It was showing an open circuit on their scanner. Then it mysteriously came back. It was looking like I might have to buy a new PCM. They said to put the old alternator back on and see what happens. So I did. & thankfully it came back to normal. Geeezz. And by the way..... The on & off whining turned out to be the water pump! Thanks for you help.