You cannot bleed the brake modulator circuit with the GS911. You can only do a bleed test that will show you if there is air or a slow leak in the brake system, for example a leaking hose or fitting, or a failing master cylinder. There is a specific procedure to bleed the brakes, both the wheel circuit and the control circuits. If you do a web search you'll find several links to forums that contain detailed instructions on how to bleed the iABS system.