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 in the rear and extended in the front from trim length, sending a "vehicle is low" signal to the control module.
^ To restore vehicle to the trim position, the 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 air springs or front spring and shock, 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 springs raise the body height, the air suspension height sensor increases in the rear and decreases in the front in length until the preset trim height is reached.
^ The control module then turns off the compressor (through the relay) and closes the air spring solenoid valves.

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