This is on my 2000 2500. I have lost both power steering and brakes. I was coming back from a trip. I got it home by being very careful. I figured the pump had quit again so I replaced it (one I replaced was only 6 months old but have had trouble with rebuilds). When I started truck it pumped some for about 15 seconds then quit. I thought maybe the hydroboost had gone out and was blocking fluid flow. Before removing it I disconnected the pressure line from pump at hydroboost. I started truck and nothing came out. So I took that pump back and swapped it. I went ahead and replaced hydroboost unit as it was warranted. Put back together and left return line from steering gear disconnected and end in a bottle to flush old fluid and bleed air. After about 15-30 seconds same thing. Quart bottle was about half full(I didn't let pump run dry) but no more flow. Could there be something in vacuum pump causing this? I need the truck going for work.