Cadillac Repair: loud clunking sound in rear end, electrical schematics, air shock

Question
I hear and can feel a loud clunk in the rear end of my 2000 cadillac deville. It has 134,000 miles.  What could this be?

Answer
In the morning look to see if the car is level or the rear end is drooping down. If it is, The fault is in most cases a faulty HEIGHT SENSOR and or an air leak in the air shock lines. You will need, If necessary, Electrical schematics and picture locations of the components within the system that is causing you problems of which can't be done on this website which only allows one picture.  I do not have a website so you will have to e-mail: onlineautohelp@msn.com in order to obtain the information.