Suspension Control ( Automatic - Electronic ): Description and Operation
Vehicle Dynamic SuspensionWARNING: The air suspension system must be shut off prior to hoisting or jacking an air suspension equipped vehicle. Failure to do so may result in unexpected inflation or deflation of the air springs, which may result in shifting of the vehicle during these operations. Failure to follow these instructions may result in personal injury.
WARNING: Do not remove an air spring under any circumstances when there is pressure in the air spring. Do not remove any components supporting an air spring without either exhausting the air or providing support for the air spring. Failure to follow these instructions may result in personal injury.
The rear air suspension system is comprised of the following components:
^ Message center
^ Control module
^ Two suspension ride height sensors
^ Compressor and drier assembly (includes vent solenoid)
^ Air tubes
^ Rear air spring and shock absorber assemblies
^ Two air spring solenoid valves
^ Compressor relay
Air Suspension System Operation
The rear wheel air suspension system operates in the following manner:
^ Vehicle height is controlled by the rear air suspension module (vehicle dynamic module (VDM).
^ Each air spring has a solenoid that must open to vent (or compress).
^ The air suspension compressor has a vent solenoid that must open to vent the system.
^ The rear air springs raise or vent together.
^ The system does not operate when:
^ any of the doors are open.
^ the liftgate or liftgate glass is open.
^ the power running boards are deployed.
^ The system will vent/compress when the vehicle speed exceeds 24 km/h (15 mph) even if the air suspension has been set to the OFF position.
^ Trim height is normal driving height.
^ The height sensor:
^ system uses RH and LH rear height sensors.
^ output voltage is between 0.5 and 4.5 volts.
^ voltage output decreases (goes from high to low) as the suspension system raises the vehicle.
^ The suspension ride height changes when:
^ the key is in the ON position, the load leveling feature automatically makes adjustments to the vehicle height so that the vehicle is always at target height and constant front-to-rear vehicle attitudes are maintained over the load range of the vehicle.
^ the key is in the OFF position, the system will remain active for 40 minutes after the ignition is turned off to make limited height adjustments as necessary.
Air Suspension Pneumatic Diagram:
