Water-In-Fuel Lamp Always on
CIRCUIT DESCRIPTIONThe fuel manager/filter assembly consists of the fuel heater, the water in fuel sensor and a filter. The filter contains the coalescer (the device that combines small droplets of water into larger ones) and the filter/separator.
As fuel enters the filter, the fuel passes first through the fuel heater. The heater contains a thermostatic switch. The switch opens or closes to turn the heater OFF or ON, depending on the temperature of the fuel.
The fuel then passes through the filter. Next the fuel flows through the water coalescer. Here the droplets of water in the fuel combine into larger drops and fall into the water reservoir in the filter. When fuel flows from the fuel manager/filter assembly to the fuel injection pump, the fuel is clean and free of water. When the water in fuel sensor touches water, the sensor closes a switch. This completes a circuit to ground for the Engine Control Module (ECM).
The driver information center in the Instrument panel cluster indicates water in fuel when the ECM commands the Instrument Panel Cluster (IPC) to indicate the condition. This is done through the Data Link (DLC) Communications, and the command is available on the scan tool.
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