CM2150 Electronic Control System – 019-127   Water in Fuel Sensor

The water-in-fuel sensor separator is located at the base of the fuel filter. The water-in-fuel sensor sends a signal to the electronic control module (ECM) when a set volume of water has accumulated in the fuel filter. The water-in-fuel circuit contains two wires, the water-in-fuel return wire and the water-in-fuel signal wire.

NOTE: The water-in-fuel sensor is the water-in-fuel signal wire and the water-in-fuel return wire in the engine harness connector.

Disconnect the engine harness from the ECM.

Check for damaged pins.

Disconnect the water-in-fuel sensor from the engine harness.

Return Wire Resistance – Checking

CAUTION  To reduce the possibility of pin and connector damage, use test lead, Part Number 3822758, when taking a measurement.

Insert the test lead into sensor return pin (common return) of the engine harness connector. Connect the alligator clip to the multimeter probe. Touch the other multimeter probe to water-in-fuel return pin of the water-in-fuel sensor, harness side.

Measure the resistance.

The multimeter must show a closed circuit (10 ohms or less).

If more than 10 ohms are measured, there is an open circuit in the return wire. Repair the wire, or replace the engine harness.

Signal Wire Resistance – Checking

Insert the test lead into the water-in-fuel signal pin of the engine harness connector. Connect the alligator clip to the multimeter probe. Touch the other multimeter probe to the signal wire pin of the water-in-fuel sensor, harness side.

Measure the resistance.

The multimeter must show a closed circuit (10 ohms or less).

If more than 10 ohms are measured, there is an open circuit in the signal supply wire. Repair the wire, or replace the engine harness.