When Weight Is Added/Removed

WEIGHT ADDED
When weight is added to the vehicle, the air suspension system responds as follows:
^ Air suspension height sensor length is reduced from trim length, sending a "vehicle is low" signal to the vehicle dynamics control module.
^ To restore vehicle to the trim position, the vehicle dynamics control module turns the compressor on by grounding the compressor relay control Circuit 420 (DB/Y). The relay is ground-side switched.
^ To allow pressurized air to enter the rear spring, the control module opens the solenoid valves.
^ Compressed air flows from the compressor, through the compressor air drier assembly, air lines and solenoid valves into the air springs.
^ As the air rear springs raise the body height, the air suspension height sensor increases in length until the preset trim height is reached.
^ The vehicle dynamics control module then turns off the compressor (through the relay) and closes the air spring solenoid valves.

WEIGHT REMOVED
When weight is removed, the air suspension system responds as follows:
^ Air suspension height sensor length is increased from the trim length, sending a "vehicle is high" signal to the control module.
^ To restore the vehicle to the trim position, the vehicle dynamics control module opens the vent solenoid valve (located in the compressor assembly) and opens the solenoid valves.
^ Compressed air flows from rear air springs, through the solenoid valves, air lines, compressor air drier and out the vent solenoid valve.
^ As the body lowers, the air suspension height sensor length decreases until the preset trim height is reached.
^ The vehicle dynamics control module then closes the vent and solenoid valves.