The following are possible causes of Hard Steering:

Loose belts Faulty power steering pump
Steering out of alignment Air in hydraulic system
Components of steering system binding Low pump output of leaks in system
Obstruction in lines Improper pump application
Low tire pressure Front axle overloaded
Oversized tires Control Valve malfunction
Internal leakage in steering gear Low hydraulic fuild
Restriction in pump flow

If you need further technical assistance please call PSS at 1-800-235-3076.