Rear air suspension all the way down

I have a 2000 bow x5 4.4i the rear air suspension is all the way down, I
checked the fuse and its ok, I checked the pump by bypassing the wires and
it's ok the pump works fine. When I turn the key to the on position, the pumps
turn on, but only for a couple seconds then it turns off, I checked and replaced
the relay and still does the same thing. The pump only turns on for one
second, has someone had the same problem before??   Please help