Ride Height Increase
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The ESCM detects a voltage signal from the rear suspension position sensors indicating the suspension height is low. The module grounds the control circuit of the compressor motor relay which in turn supplies battery voltage to the compressor. The exhaust valve is open for 1.5 seconds during compressor pump start up in order to reduce current draw and pump motor wear. Air pressure from the compressor is pumped to the rear shocks through small flexible tubing. The increased pressure inside the rear shocks raises the suspension to trim height.