SENSOR, Water in Fuel: Operation: Operation
WARNING: This page is about a different car, the 2011 RAM Pickup and 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The sensor sends an input to the Powertrain Control Module (PCM) when it senses water in the fuel filter/water separator. As the water level in the filter/separator increases, the resistance across the Water in Fuel (WIF) sensor decreases. This decrease in resistance is sent as a signal to the PCM and compared to a high water standard value. Once the value reaches 30 to 40 kilohms, the PCM will activate the water-in-fuel warning lamp through CCD bus circuits. This all takes place when the ignition key is initially put in the ON position. The PCM continues to monitor the input while the engine is running.