Flex Fuel
WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
Flex fuel vehicles use alternating current (AC) for the sending unit, which is then converted by the cluster to direct current (DC). The direction of the current through the fuel sender resistor is switched by the cluster at a rate of 50 Hz with 50% of the duty cycle in each direction. The instrument cluster (IC) senses the variable resistance of the fuel sender by supplying voltage across the pins of the fuel sender. This voltage varies based upon the value of the fuel sender resistance, which is determined by the level of the fuel sender float, and the battery voltage.