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 indicator.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

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 low reference circuit terminal B and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, observe the Water In Fuel Sensor parameter. The parameter should display No Water.

⇒	If parameter does not display No Water, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. The Water In Fuel Sensor parameter should display Water.

⇒	If a 3A fuse opens and the Water In Fuel Sensor parameter displays No Water, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

⇒	If the Water In Fuel Sensor parameter displays No Water and the 3A fuse did not open, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

5. Ignition ON, perform the IPC lamp test and verify that the water-in-fuel indicator turns ON and OFF when commanded from the scan tool.

⇒	If the water-in-fuel indicator does not turn ON and OFF, replace the IPC.

6. If all circuits test normal, test or replace the water in fuel sensor.

1. Remove the water in fuel sensor.
2. Connect a DMM between terminal A and terminal B of the sensor harness connector.
3. Measure the resistance of the sensor while moving the float up and down the float barrel.
4. The resistance should switch from less than 0.5 ohm and 0.L.

⇒	If the resistance did not change, replace the water in fuel sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.