Air Suspension

1999 Explorer XLT 5.0L w/towing package - approx. 56,000 miles. Automatic Air Suspension load leveling worked fine until about a couple of months ago (used to be a little annoying when I'd get in and I'd hear the air pump engage to re-level the vehicle!) I checked the ON/OFF switch connection in the back and cycled it a few times, still no action. The "Check Air Suspension" light does illuminate upon startup, then goes off, as it always has. Anything else I can check before taking it in to dealership? Thanks!