I had problem with my prius power steering, everything was looking fine like the fuses, relays. But the PS sign was there and the Emps wasnt working either, tried to find the solution but all in vain. In the last we decided to change the racks it didnt work too, one guy who works with Electric and famous he assumed the Ecu for Emps is bad, luckily i have the same prius which is in runing position. I switched the Ecu which wasworking on the other car, then i went thoroughly after all this and i found the one cable is broken has no continuity. Its from the Emps relay to the Ecu of grey color. I made a jumper of this cable and after that everthing was fine, but took me lot of time come to the solution.