Not sure on yours, But on my car, PS is via a pump driven by a belt, front of engine, Enigne not running, no PS. Belt slipping, when engine running, poor PS, depending on how bad the slip, so check your belts, I lost totally PS, just after starting up one day, I had just pulled off, It was a real struggle to repark, just the few yrds. Belt had snapped.
SD
January 2012