A hydrostatic steering system has a steering cylinder for coupling to steerable wheels, a gerotor pump, a steering valve and an actuator controlled mode select valve. The steering valve is mechanically and hydraulically coupled to the gerotor pump, and controls fluid communication between the gerotor pump and the steering cylinder. The steering valve has a center position wherein communication between the gerotor pump and the steering cylinder is closed. The actuator controlled mode select valve controls fluid communication between the gerotor pump and the steering cylinder independently of the steering valve.