Fuel Cap Off Indicator Light
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2002 Mercury Sable, 2002 Mercury Mountaineer, 2002 Mercury Grand Marquis, 2002 Mercury Cougar, and 2002 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Continental, Escape, LS, Mustang, Thunderbird, Town Car and Windstar do not have a dedicated output wire from PCM to instrument cluster. PCM commands Fuel Cap Off Indicator Light (FCIL) on and off through Standard Corporate Protocol (SCP) BUS (+) and BUS (-) circuits.
FCIL is an output signal controlled by PCM and will illuminate when it is determined there is a failure in vapor management system due to fuel filler cap not being sealed properly. This would be detected by inability to pull vacuum in fuel tank, after a fueling event.