Circuit/System Description
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
A sensor/switch mounted in the bottom of the fuel filter housing is used to detect water in the fuel. The water in fuel (WIF) sensor/switch has a signal circuit and a low reference circuit. The engine control module (ECM) monitors the voltage to the WIF sensor/switch. If the voltage is incorrect, the WIF lamp will illuminate or WATER IN FUEL SERVICE REQUIRED will display on the driver information center (DIC) as applicable, and set this DTC.