I am hearing a fairly noticeable "groan" when I turn the wheel in either direction. I haven't gotten too deep into the diagnostic process yet, as I don't spend much time at home (travel for work WAY too much). I have looked at the PS fluid reservoir (full), and inspected underneath (looked it over) for anything noticeably wrong and found nothing. There is no squeal from the pump, making me think that the pump is still working, however, it has gotten progressively harder to turn the wheel while not rolling. This is beginning to concern me. The truck is an 03 SSS, all wheel drive, with just under 100K on it. Has anyone experienced something like this? I am confused.

 

I had a noticeable groan in mine when I bought it and it was coming from the steering gearbox. Function was not affected though, it was just really annoying. I flushed the system out several times and have it reduced to only the occasional light groan under extreme turns.

I would start by flushing the PS system really well and see if it helps.