I work at a Cadillac dealership and im working on a 2004 XJ8. I brought the vehicle into the shop the other day and the suspension height was normal. Today after I had finished all the services on the vehicle, I noticed the front suspension sagging and touching the inner fender wells. After starting the vehicle, i let it sit in the shop for about 20 mins to see if the bags would air up but after running the bags would not air up and the compressor would not engage. I have already inspected the air bags and the air lines for leaks and the air bags/lines are ok. I have also already checked the compressor fuse and the relay and found both were ok. I did however found that there was no power going to the compressor, but i do know the wiring is ok going from the fuse block to the compressor. If anybody and help me out it would be greatly appreciated!!

 

Sounds like the compressor is bad or struggling with the cold weather. Mine is giving me issues down here in Austin, where, I'm sure, it isn't as cold as it is up where you are.

Does the "Air Suspension Fault" or "Vehicle Too Low" message appear on the dash?

 

try driving it around the block for up to 20 mins.

 

Are the electrical connections to the air-valve block OK?

 

Are there any fault codes, and have you read them ?

I see you're in Michigan and the weather has been ever so slightly cold there. Was the car in a warm shop ? If the car is low, and the compressor isn't coming on to charge the reservoir, I'd suspect the front height sensor.