As it turns out, the power steering AND the braking system share the same reservoir which was 'cleaning the bottom side' of my vehicle real good, but steering fluid was getting very expensive and cleaning the bottom side was not useful!! The ABS 'manifold' (my word) for the rear brakes, was ultimately the culprit dropping the fluid. A new 'gizmo' from Toyota (or some scalper) was $1000. My mechanic bypassed the rear ABS gizmo with $25 worth of tubing and more than a little creativity. Total cost: $150. Not a drop of leakage now!!