Power seat problem

[jfinch]

I have a 98 ML 320. I had a problem with the passenger power seat the other night. Seat would move forward but not backward. I kept fiddling with it and wound up with the seat all the way forward and it would not go back. I could hear the switch clicking but the seat would not move. Finally something caught and it started moving back so I moved it all the way back. My question is does it use relays to activate the seat motors? If so where are they? If not is everything controlled from the switch on the side of the seat?