For one thing pulling the battery cable off while the car is running is an excellent way to fry the alternator and other electronic parts. The alternator will see no load and the voltage will max out. Usually somewhere around 17 V or so.
If the steering is very hard to turn it is either the pump or the rack. When the car is running at idle it doesn't take long to circulate the entire contents of the PS system. You should be able to see the fluid turbulence inside the reservoir when idling. If there is no turbulence the pump isn't pumping or it is blocked.