Glow Plug Indicator Lamp (GPIL)
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2005 Ford RV Cutaway, 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
The GPIL is located in the instrument cluster and is used to inform the operator when the engine is ready to be started. The indicator is controlled by the instrument cluster based on an electronic command signal from the PCM through the standard corporate protocol (SCP) communications network (Excursion) or the controller area network (CAN) (F-Super Duty or E-Series). The on-time normally varies between 1 and 10 seconds and is independent of the glow plug relay on-time. As a prove out, the indicator is commanded on at every key cycle even though the glow plug system may not be required.