Hy speed6351, is the brake system warning light hooked up? You can test the switch with a meter or a test light, if the valve has shuttled over, the terminal will be grounded. If the valve has shuttled over to close off the front system you can attempt to reset it. First bleed the front calipers, they will gravity bleed, once you have them bled as best you can, then pump up the brake pedal and have someone crack open a rear bleed screw, if you do this with the ignition on, and the wiring on the combination valve the light should go out when the valve shuttles towards the rear system, be gentle, or you'll send the valve all the way to the rear. Sometimes you have to chase it back and forth a bit, hope that helps.