I've been watching your YouTube videos for a couple years, and I've learned a lot from you.
I have a 2015 Cadillac XTS with 74,000 miles. The car rides great, but between parking it last night and getting in it this morning, the rear air suspension seems to have lost all its air. When I started it, the air compressor came on and raised the rear of the car a little, but it never returned to its normal height. I drove it about an 1/8 - 1/4 of a mile down the street and back and it lost all its air. I checked for leaks using soapy water and found none. I also checked the electrical connections and found no issues (no rust, no dirt, no bugs, no loose connections). The "service suspension system" light on the dash has never illuminated, and the car has acted completely normal until this morning.
I've worked on my cars since I was a teenager and I've always been able to located the problem and fix it myself, except for transmissions problems, which I no longer even attempt to do myself. This suspension issue has me stumped.
How much is your diagnostic fee? And when could you look at it?
I live in Porter, and I think I recognize your house from your videos as I used to work and live in your neighborhood too. Would it even be a good idea to drive the car to you like it is, or could I cause more damage?
A big fan,