Steering very tight when hard braking
 

I did a site search through google, but didn't come up with much on my specific issue.

I have a 2004 TL Base that seems to be running fine for its age and mileage. I have done some repairs and basic maintenance in the few months ive had the car, but have not driven it hard to check it out until today.
I have overhauled the Power Steering pump and replaced all the seals in the steering rack. I followed the service manual to a T (mostly). There were a somethings I didn't mess with since I did not have the tools for it.

Anyhow... When driving normal the steering is fine and feels as it should for a TL, but if I brake hard my steering gets really tight. Almost impossible to turn the wheel for several seconds. Several seconds after I let off the brake and return to normal driving, my steering is back.
Do any of you mechanically savvy members have any idea what could be the issue?

When was the last time you replaced your PS fluid? Is their air in it perhaps?

Thoiboi. A month or so ago. Didn't have any air bubbles after I followed the PS fluid replacement procedure. I'll check for air bubbles shortly though.

Well. I steered it left/right a few times, 50 or so, and I did see a few (less than 10) bubbles on the surface on the PS fluid. No leaks that I can discern.

Took it out for a 30 min drive cycle, along my drive I had to brake hard and noticed my steering got really stiff once more. Seems like intermittent issue.
Might replace the PS pump. Any thoughts?

Do you have vaccum leaks? Does the idle dip pretty far down when you apply the brakes?

Does it only happen when you're in gear?

Does the car need to be moving for the steering to become stiff? Or can you do this while sitting still?

Answers in Red

The PS starts to taper off as the car goes faster. You need less assist when speed is higher.

Maybe there is an issue with the pressure switch or pressure reading.

Have you had the car inspected?

I was thinking there might have been an issue with the p/s pressure switch. I need to look in the service manual for a test procedure. Will reseat connector later and drive around. Its pouring rain right now..
By Inspection do you mean a mechanic or state emissions?

I ended up replacing the whole P/S pump on Saturday afternoon. No issues so far. From poking around with the old pump, to me it seems the flow valve is sticking. (hard to slide back/forth in housing).

if you're so inclined and don't have a core charge, you could follow the rebuild guide and take it apart to see exactly what was going on