WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.
The following illustration shows the arrangement of the power steering components and lines.
Fig 1: Identifying Power Steering Components And Lines
Courtesy of BMW OF NORTH AMERICA, INC.
Check all visible connections, hoses, lines and steering gear for traces of fluid.