Pump1 has a load sensing priority valve on the bottom. steer always gets priority. That being said, the contorller monitors amp draw from motor. the amps on the motor will go up with more hydraulic demand if the pump is good and building proper pressure. If pressure is not loading down the motor it will not speed up to move the volume needed to properly steer and/or run accessories. I just replaced a pump 1 on a 5200 monday due to this issue, only mine was "strong arm" steering due to not enough hydraulic pressure from the motor not speeding up with hydraulic demand.

Update: Sorry just notice this is a really old post... Dont know how I ended up this far down on the threads! lol But I will leave my note here for others.