Lowering the Vehicle

Fig. 6 Height sensor operational test:

When the weight on the rear of the vehicle is removed, the body immediately moves higher. This high condition has the effect of rotating the height sensor actuating arm downward. The height sensor then senses the high condition and starts the time delay circuit. When the time delay has elapsed, the sensor then completes the exhaust solenoid circuit to ground. With the exhaust solenoid energized, air starts exhausting out of the shocks back through the air dryer and exhaust solenoid to atmosphere.
As the body moves downward, the height sensor actuating arm is rotated toward its original position (position before weight was removed). When the vehicle reaches its original height within 3-4 inch, the sensor opens the exhaust valve solenoid circuit, preventing the air from further escaping.
A minimum pressure of 8 - 15 psi on all models is maintained in the shocks by the air dryer retention valve. The minimum pressure provides improved ride characteristics when the vehicle is at minimum loading.