GM Service Manual Online
For 1990-2009 cars only

With the power lumbar system, each seat incorporates a power lumbar motor, lumbar solenoid and a power lumbar support switch to inflate/deflate an air bladder for changing the contour of the seat back. The power lumbar support switches are three position switches that energize the power lumbar support motor and the lumbar solenoid to inflate the lumbar bladder and energize only the lumbar solenoid to deflate the lumbar bladder.