Circuit/System Description
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
A sensor mounted in the bottom of the fuel filter housing is use to detect water in the fuel. The water in fuel (WIF) sensor has an indicator control circuit and a low reference circuit. The engine control module (ECM) monitors the voltage to the WIF sensor. If the voltage is incorrect, the ECM will illuminate the WIF lamp and set the appropriate DTC.