2003 GMC Sonoma Owner's Manual - Page 11

Power Seats If your vehicle has this feature, there will be a control on the outboard side of the front seat(s). Vertical Control: Move the reclining front seatback forward or rearward by moving the control toward the front or rear of the vehicle. Manual Lumbar If your vehicle has this feature, there will be a knob located on the outboard side of the driver's seat. Horizontal Control: Raise or lower the front of the seat by raising or lowering the forward edge of the control. Raise or lower the rear of the seat by raising or lowering the rear edge of the control. Move the seat forward or rearward by moving the whole control toward the front or the rear of the vehicle. Moving the whole control up or down raises or lowers the whole seat. Turn the knob counterclockwise to increase lumbar support and clockwise to decrease lumbar support. 1 -4