I have a '91 LS400 with 116,000 miles on it. Both front, and one rear, air struts have been replaced in the last five years. Recently, when the car is parked and not driven for two days or so, the front of the car drops all the way down, both sides equally. When I start the engine, the air suspension pumps back up fairly quickly, and I have no problem with maintaining ride height while driving.
Since the problem is common to both sides, and only the front, I suspect a check valve, or something similar, which is supposed to hold the air pressure to both front struts when the engine is off. Possibly the Ride Height Control Valve #1? Has anyone else had this problem, and what was done to correct it? I want to have as much information in hand as I possibly can before going in to the Lexus dealership for repair. Thanks for your help.