Started getting air ride message about 4 months ago on startup - sometimes. Did switch-off-in-trunk leak test and drove car for 3 DAYS with no noticeable leakdown. Turned switch back on and startup pumping & leveling worked OK for about a week, then message started coming back, about every 3rd startup. I decided that the factory-original compressor was getting tired at 109K miles, and installed a rebuilt compressor/dryer from a reputable source. System worked OK for about 3 startups, and then message came back. OK I thought; it must be the relay. I first cleaned the relay & connector contacts with tuner cleaner to rule out corrosion and then coated the terminals & connector gasket with tune-up grease, re-connected relay and started it up. It worked fine for a few days, then the message re-appeared, again at (seemingly) random. I then thought it MUST be the relay, so I swapped the relay with the one for the ABS; again, the system was OK for a few days, then the message came back.
When the message appears, the compressor will start and run for 3~5 seconds, the front solenoid valves open and close in rapid succession, the compressor quits, and the message appears. If I wait a few minutes (or even a few seconds) and re-start the car, the system will work as if it just came from the factory, with full leveling front & rear achieved in less than 30 seconds. My charging system (near-new alternator) puts out 14.4 volts when cold, so it's not that; what else can cause this intermittent condition? Thanks for any help in this matter.