Air Suspension Depressurization
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
To depressurize the Air Suspension System install the scan tool with key in the on position. Go to the special functions menu of the Air Suspension section and follow the on screen directions. The suspension will deflate the air springs until the suspension is on the jounce bumpers.