1999 Cadillac Deville Air Ride

I just bought this car. I had a rattle in the rear of the car and put the rear end of the car on drive on ramps and got under it. I found a plug in connector unplugged. I plugged it in. A short while later I heard the Air ride compressor kick in and pump up, the rear of the car rose to what I assume is the maximum height and has remained there every since. This was about 5 days ago. I do not see it bleeding off, nor do I hear the compressor cycle or run, nor will the rear end of the car go back down level. I read your article about this system, and saw where you have SYSTEM DOES NOT EXHAUST test under SYMPTOM TESTS. I cannot find the Symptom Tests area of your website. The rear of the car is setting up at least 4 or 5 inches, so the height adjustment does not seem to fit this problem. Before plugging the connector in, the car set level, and road like a dream, not it is a rougher ride, the headlights are aiming to low. I am sure it has to do with the system not exhausting the air from the pumped up shocks. Any advise would be greatly appreciated or at least the link to the Symptom Tests page would help. I am capable of replacing parts and running the necessary manual tests. Thank You all, Charles, The Leatherman