2005 GMC Envoy Owner's Manual - Page 11

Manual Lumbar If your vehicle has this feature, there is a knob located on the outboard side of the driver's seat. Power Lumbar Your vehicle may have this feature. The control is located on the outboard side of the seat cushion. Turn the knob counterclockwise to increase lumbar support and clockwise to decrease lumbar support. 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. 1-5