I have a 2008 Toyota Sienna LE and it is exhibiting an odd sound in the steering.
The sound only happens after the vehicle has been driven at least 10 minutes. I started cold and idled for 20 minutes, and no sound.
The sound happens only when I turn the steering wheel and the best way to describe is a relatively quiet ticking/whirring sound and vibration that is nearly perfectly rhythmic with the turning. It is also almost impossible to hear when I pop the hood and turn the wheel with my head over the engine, but very easy to hear inside the van with the door closed.
The power steering fluid hasn't lost a drop as near as I can tell and my mechanic serviced the vehicle a couple of months ago and told me the fluid was in good condition and no need to change.
I've never had a problem like this with steering, so I'm not sure where to begin.