gilnjo

Recently purchased 2007 ML350. Love the car; one little nagging issue. On the driver's seat control, all functions work properly except on the seat cushion control. Forward/backward movement OK; front of seat cushion up/down OK, but back of seat cushion (where it joins the backrest) up/down is inoperable. Feels like it's stuck in the lowest position and no movement upon moving the back of the seat cushion switch on the side of the seat. Switch? motor? fuse? relay? Thanks in advance for any suggestions.