Hard steering

I have a 2001 F-250 SD 7.3 that drives fine, brakes feel good, my issue is steering in a parking lot. It gets very hard (impossible) to steer at low engine speed, especially when using the brakes. I have to jockey back and forth, or put the trans in neutral and rev the engine to turn the wheels to get into a parking slot. Now I know the brakes and P/S share the same pump, but is there a way to test the pressure output of the pump? It makes no noise, fluid is full, no leaks. It will not do a lock to lock turn sitting still, I do not know if this is normal. Been like this for the time I've had the truck, 2 years, I'm not sure if it is getting worse, or if I'm getting less tolerant of it. 4X4, auto, slightly oversize tires, but no lift, or aftermarket rims etc. Should it turn lock to lock sitting still, in gear, with the brakes on?

Is the pump different from a gas application? Whats a good replacement if that's the issue? The gearbox seems fine as far as wandering or excessive play.

Thanks.

Yes it should if you don't have BIG tires (you don't). Maybe time for a new pump.

yeah...my '02 is getting harder to turn as the years go by but it still can turn 'lock to lock' standing still. I don't know if the pump is same in a gasser, probably not, according to a quick remanned Motocraft parts number check on RockAuto.com between V10 and 7.3 in 2002.

Well it was the pump. I don't believe I've ever had one actually wear out before. Leaked, bearings fail, but never worn out. Easy fix, under 50 bucks from O'Reilly's, lifetime warranty. Hard to beat. I did find the old fluid was red which would seem to indicate that the last owner had used ATF in the system. I left the return line off and flushed it out best I could with P/S fluid. Thanks for the advice, as always, spot on.