If there is water in the fuel system, the water in fuel sensor switch will close and produce a low voltage on the signal circuit. When the engine control module (ECM) detects a low signal from the water in fuel sensor the ECM will send a serial data message to the instrument panel cluster (IPC). The IPC will then illuminate the WATER IN FUEL SERVICE REQUIRED message in the driver information center (DIC).

Schematic Reference

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References

1. Ignition OFF, disconnect the harness connector at the water in fuel sensor.
2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal B and ground.

⇒	If greater than 1 ohm, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Verify the scan tool Water In Fuel Sensor parameter is No Water.

⇒	If not No Water, test the signal circuit terminal A of the water in fuel sensor for a short to ground. If the circuit tests normal, replace the ECM.

4. If all circuits test normal, test or replace the fuel strainer bowl.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.