I have an 06 Infiniti QX56. I noticed the rear was sagging, and couldn't tell if the compressor was working. I watched YouTube videos, and looked up forums, I had changed out the suspension relay behind the battery, I changed out the rear shock absorbers, I tested the air ride sensor, and try to bypass it, then I just now replaced the compressor itself. When I pulled out the lines, air pressure was released, plugged in the new air compressor, and it still did nothing. What am I missing, or what else could it be?