A seatbelt retractor assembly includes a disk having a cam surface and a cam follower surface. A lever that engages the cam surface when the lever is in a disengaged position and engages the cam follower surface when the lever is in an engaged position. The lever moves from the disengaged position to the engaged position in accordance with rotation of the disc. A Hall effect switch detects whether the lever is in the disengaged position or the engaged position.