Power Steering hard at idle

My 2006 Tundra is really very hard to turn at idle, feels like trying to turn the wheel when the engine is off. I replaced the air control valve which was leaking which did not solve my problem.

Steering works fine at even slightly higher RPM, even when the RPM kicks up 100-200 rpm when an accessory kicks on like A/C or my fan. How do I diagnose if this is the pump, rack, or something else?

 

How does the truck behave when both wheels are jacked up, truck on stands, with engine is running, and you turn lock to lock? Is it still stiff?

Have you been through the service manual for power steering diagnostics yet? Link to one is 4th/5th sentence here.

EDIT: And you didn't do anything silly, like you know the power steering in your truck uses ATF, right? Any maintenance done, or any accidents we should know about, prior to this happening? Have you jacked up the truck recently to push/pull test the balljoints and tie rods, checking for play?

 

Thanks Shifty for following my other questions!

With the truck on stands the steering turns freely at idle, the hard steering occurs at any position, it seems to be a matter of rpm. I got impatient and swapped the power steering pump with a salvage one that I had and I still have the same hard steering characteristics.

I flushed the power steering with ATF when I first started working on this issue when I replaced the PSCV. I replaced the upper balljoints a few months back, everything is in good condition (except I need to replace the strut bushings, likely just replace the struts). The previous owner did hit a deer but that damage seemed to be mostly cosmetic. The power steering rack is refurbished so that obviously has been replaced at some point....

Thanks for sending the service manual link, that will be handy for a while! I went thru the diagnostics and nothing seems to line up with what I have going on.

On another thread someone deleted the PSCV while they did a repair for a few weeks and said they noted that they could not really tell a difference so while it seems like if I had a bad replacement PSCV or vacuum leak (hoses appear to be in good shape and connected) I should still have decent steering at low idle.....

 

Have you tested for vacuum on the PSCV valves, to confirm you're actually getting vacuum? Have you confirmed the lines for the PSCV are actually routed correctly to something that would supply vacuum?

My thought process being here - and I don't fully remember how PSCV works, but I thought vacuum caused it to kick RPM up - but if it's not routed to a vacuum source, maybe it's not pulling needed vacuum to do that.

 

I'm going to resurrect this old thread because I'm having the same exact issue. Last year I replaced my power steering rack all the lines and hoses as well as the power steering pump and it works fine for about a year and all of a sudden one day my power steering gets incredibly stiff backing out of my driveway.
I had an extra PS ACV and swapped it in just to see if that would make a difference and nothing. My next step is what Shifty said and testing to see if I have vacuum coming from the two parts on the intake and on the throttle body side.
The one weird thing that may or may not be connected is I started throwing a check engine light for my secondary air injection system pump. I'm wondering if a failure in that can cause a vacuum leak significant enough to cause the power steering to be inoperable at low RPM but otherwise unaffected drivability?
I currently don't have power steering unless I'm over 2000 RPMs