The suspension air control system uses air drawn from the vehicle air system in order to pressurize the air spring assemblies through the height leveling valve.

The correct vehicle ride height is maintained through use of a frame-mounted height leveling valve.

The pressure protection valve is located on the front service reservoir. The pressure protection valve protects the air supply to the brakes if a failure occurs in the air suspension system. If a loss of air occurs forward (upstream) of the protection valve, air pressure within the air spring system will be partially maintained until repairs can be made. If a loss of air occurs rearward (downstream) of the protection valve, the air in the brake system will be protected but the air pressure in the air springs will be lost.