When Weight Is Added/Removed
WEIGHT ADDEDWhen weight is added to the vehicle the air suspension system responds as follows:
^ The air suspension height sensor length is reduced from trim length, sending a "rear is low" signal to the control module.
^ The control module then turns the compressor on by grounding the compressor relay control Circuit 420 (DB/Y). This restores the rear of the vehicle to trim position.
^ B+ is supplied to the relay coil by Circuit 1053 (LB/PK).
^ The control module opens the spring solenoid valves by switching Circuits 1114 (BR/PK) and 1115 (T/W) to ground. This allows pressurized air to enter the rear springs.
^ B+ is supplied to the air spring solenoid valves by Circuit 1053(LB/PK).
^ Compressed air flows from the compressor through the compressor air drier air lines and spring solenoid valves into the rear springs.
^ As the rear springs raise the rear body height, the air suspension height sensor increases in length until the preset trim height is reached.
^ The control module then turns off the air compressor (through the relay) and closes the air spring solenoid valves.
WEIGHT REMOVED
When weight is removed:
^ The air suspension height sensor length is increased from the trim length, sending a "rear is high" signal to the control module.
^ The control module then opens the vent solenoid valve (located in the air compressor) by switching Circuit 421(PK) to ground and opens the solenoid valves by switching Circuits 1114 (BK/PK) and 1115(T/W) to ground. This restores the rear of the vehicle to trim position.
^ Compressed air flows from rear springs, through the air spring 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 control module then closes the vent and solenoid valves.