[HUMTECH]

Well the procedure is lift the rear of the truck, and install the calibration blocks between the bump stop and diff housing (every Hummer dealer should have these as an essential tool) depressurize the air suspension system. With the tech 2 go to chassis, air suspension, special functions and then trim height learn. If everthing is good trim height learned will be displayed. raise the rear off the calibration blocks and remove them. close all doors, run truck and verify system works.