Water in Fuel Indicator (Diesel only)
WARNING: This page is about a different car, the 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, 2003 Ford Excursion, and 2003 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The water in fuel signal is transmitted to the instrument cluster via the SCP network from the powertrain control module (PCM). The water in fuel indicator will illuminate when 100 cc (0.2 pints) of water has accumulated in the fuel filter/water separator.