Water-in-Fuel Lamp Diagnosis

Water-in-Fuel Lamp Diagnosis

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The Water In Fuel Sensor is a 2 wire sensor that monitors the presence of diesel and water. When water is present the Engine Control Module (ECM) detects low voltage on the signal circuit and sends a serial data message to the instrument panel cluster to display the WATER IN FUEL SERVICE REQUIRED message.

Reference Information

Schematic Reference

Engine Controls Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

Description and Operation

Fuel System Description Fuel System Description

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

Note: If other contaminants are noticed in the fuel, a fuel system flush may be necessary.

2. Verify there is NO water in the fuel
Refer to Water-in-Fuel Draining Procedures

• If there is water in the fuel, drain off water completely

• If there is NO water in the fuel

3. Ignition ON.

4. Verify the water in fuel lamp turns ON and OFF when commanded with a scan tool.

• If the Water in Fuel lamp does not turn ON and OFF
Refer to Symptoms - Displays and Gauges Symptoms - Displays and Gauges

• If the Water in Fuel lamp turns ON and OFF

5. All OK

Circuit/System Testing

Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, and all vehicle systems OFF. Disconnect connect the harness connector at the B116 water in fuel sensor. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 5 ohms between the ground circuit terminal 2 and ground.

• If 5 ohms or greater

1. Ignition OFF.

2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open or high resistance in the circuit.

• If less than 2 ohms, repair the open/high resistance in the ground connection.

• If less than 5 ohms

3. Ignition ON

4. Verify the scan tool Water in Fuel Sensor parameter displays No Water.

• If the scan tool does not display No Water

1. Ignition OFF, disconnect the X3 harness connector at the K20 engine control module.

2. Test for infinite resistance between the signal circuit terminal 2 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.

• If infinite resistance

3. Test for less than 2 ohms in the signal circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms

4. Ignition ON

5. Test for less than 1 V between the signal circuit and ground.

• If 1 V or greater, repair the short to voltage on the circuit.

• If less than 1 V, replace the K20 engine control module.

• If the scan tool displays No Water

5. Replace the B116 water in fuel sensor.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Water in Fuel Indicator Sensor Replacement Removal and Replacement

* Control Module References Control Module References for replacement, programming, and setup.