Ford 1999 Taurus Owner's Manual page 181

ignition switch is in the ON position and the
shutoff switch is in the OFF position. "CHECK AIR
RIDE" will appear when a system fault has been
detected and the ignition switch is in the ON
position.
Normal vehicle operation does not require any
action by the driver.
176
The air suspension switch — located behind
the left-hand vertical trim panel in the trunk