2002 envoy power steering hard at idle

My 02 envoy XL has no power steering at idle. If you rev up the engine you get power steering. Does this sound like a rack or pump issue? How do I diagnose it? The pump is under 1 year old. The rack has about 70K on it. Seems premature either way. The power steering fluid is always dirty in this vehicle. Could it just be dirty fluid?

Thanks,
Jeremy

Only a pressure test of the pump will properly diagnose the problem.

What's a good way to check the pressure? Does a guy buy a power steering gage kit or is there a hard ware store alternative? What type of pressures should you see at idle?

I'm assuming if the pressures at idle are fine then the rack is the next suspect?

Thanks,
Jeremy

The connections are specific for p/s testing as well as a gage that can read up to 1000#, this is an expensive specialty item around 150.00. Idle pressure varies in every model you will need a shop manual or other source for the specs. But look at about 300- psi minumum , check on this first. Also make sure there is no binding in the steering linkage such as a frozen tie rod end.