The Yellow and Orange relays are the aux fan high and low speed, I believe. The third spot is also empty in my car (94 525i), so I don't think you are missing anything. Under the hood on the driver's side is a 4" x 5" fuse box which contains the fuses for the ASC, and the ABS (each being 25 amps). Also in this box is a yellow and a orange relay and a spot for a third relay. Does anybody know what this third relay controls. I ask this because I am missing the relay and there are wires going to the harness. Any help would be appreciated.