Theory Of Operation
WARNING: This page is about a different car, the 2017 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
There are two Water-In-Fuel (WIF) sensors attached to the two fuel filters. WIF 1 is attached to the fuel filter mounted on the engine. WIF 2 is attached to a 2nd fuel filter that can now be found mounted to the chassis. The Powertrain Control Module (PCM) provides a 5-Volt reference signal to each WIF sensor. When the water collected in the respective fuel filter covers the sensor probes, the sensor then pulls the 5-Volt reference voltage low indicating high water accumulation in that fuel filter.