GM Service Manual Online
For 1990-2009 cars only

Your vehicle may have this feature. The driver's and passenger's seatback lumbar support can be adjusted by moving a control located on the outboard side of the seat cushions.

To increase or decrease support, hold the control forward or rearward. Keep in mind that as your seating position changes, as it may during long trips, so should the position of your lumbar support. Adjust the seat as needed.