Fuel Cap Indicator Lamp
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2005 Mercury Sable, 2005 Mercury Mountaineer, 2005 Mercury Monterey, 2005 Mercury Montego, and 2005 Mercury Mariner. However, it is still accessible from the selected car via links, so may be relevant.
The fuel cap indicator lamp (FCIL) is a communications network message sent by the PCM. The PCM sends the message to illuminate the lamp when the strategy determines that there is a failure in the vapor management system due to the fuel filler cap not being sealed properly. This would be detected by the inability to pull vacuum in the fuel tank, after a fueling event.
NOTE:
The FCIL on the Crown Victoria/Grand Marquis, Explorer Sport Trac, and Ranger is a dedicated output signal that is controlled by the PCM.