Very loud steering whine on '08 Tahoe

[08HoeCD]

My steering whines super-loud about 30% of the time when I am turning the wheel sharply at parking speeds but before full-lock. It's such a loud whine that people standing 50 ft away stop, turn and stare.

I changed my power steering fluid a couple of weeks ago and the reservoir is filled to the correct degree. Is this loud whining a symptom of a system that's failing?

 

[John l]

Every gm I have worked on since 00' when you here the whine change the power steering pump