Disclosed herein are embodiments of a wire harness assembly for routing a wire harness through a vehicle seat back having an active head restraint system. The assembly can comprise a movable member configured to move relative to a seat frame in a vehicle fore-aft direction and can have a sleeve with a first end configured to receive a headrest. A harness guide is included with a guide tube and an attachment member that is connected to the guide tube and to the movable member, the guide tube having a first open end and a second open, and a guide passage that extends through the guide tube from the first open end to the second open end. A second end of the sleeve opposite the first end is located within the attachment member and configured such that the sleeve and the attachment member move with the movable member.