The 2002-2009 GMC Envoy is built with the following suspension components:
2002-2009 GMC Envoy Air Springs (x2)- commonly referred to as air bags, a plastic and rubber bag that uses pressurized air as a cushion to support the weight of the vehicle. These rubber air springs are the number one cause of all air suspension leaks. Since air springs go bad at about the same rate, if one is leaking, the other one will not be far behind. For a proper repair, all of them need to be replaced at the same time.
2002-2009 GMC Envoy Shock Absorbers (x2)- these control the wheel-to-ground contact for the rear of this vehicle. Shocks dampen vibration and bounciness caused by rough road conditions.
2002-2009 GMC Envoy Height Sensors (x2)- a linkage located near each wheel of a vehicle with any electronic suspension that, either mechanically or electronically, constantly measures the height of the vehicle, and reports this information back to the control module so that the computer can identify if changes in height need to be adjusted accordingly. The ride height sensor is a moving part, and like all moving parts, they will eventually wear out.
2002-2009 GMC Envoy Air Lines- tubes that run from a compressor to the air which carry pressurized air to the air bags in order to adjust the height of the vehicle, respectively.
2002-2009 GMC Envoy Solenoids (x2)- these plastic components work along with the control module on vehicles with active suspension. The solenoid regulates the air pressure for each air spring. Solenoids start to leak as they wear out causing the vehicle to sag or to lean. This will cause the ride height sensor to send a signal to activate the compressor in an attempt to inflate the air suspension and level out the vehicle. This excessive work load will eventually lead to total failure of the compressor.
Compressor Assembly- creates/sends pressurized to active suspension components. When the air suspension starts leaking, the compressor/pump starts working harder to try to keep the system inflated. By the time air suspension leaks down completely, sitting the vehicle on its tires, the compressor will either have failed or be well on its way to full failure. Buying replacement struts and taking the time to install them only to find out the compressor still needs to be replaced can be very frustrating, time-consuming, and expensive.
2002-2009 GMC Envoy Dryer- prevents moisture build-up inside of air suspension parts.
2002-2009 GMC Envoy Suspension Control Module- a computer which is responsible for the operations of the air suspension system and maintaining the vehicle's correct ride height.
2002-2009 GMC Envoy O-rings- Although they are the least expensive parts of the air suspension, they are responsible for maintaining the seal where all of the air lines connect. Be sure to replace the O-rings when repairing any air suspension system.