Diagnostic Aids

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The water in fuel sensor illuminates the Water in Fuel message when there is water in the fuel system. Perform the Water in Fuel Draining procedure before performing the following test steps to accurately determine if a malfunction exists. Refer to: Water-in-Fuel Draining Procedure in Engine Controls - 6.6L.
For intermittent diagnosis, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Water-in-Fuel Lamp Inoperative

Step	Action	Yes	No
Schematic Reference: Instrument Cluster Schematics and Engine Controls Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems
1	Did you perform the Instrument Cluster Diagnostic System Check?	Go to Step 2	Go to Diagnostic System Check - Instrument Cluster
2	Turn the engine OFF. Disconnect the water in fuel sensor. Connect a 3-ampere fused jumper wire between the signal circuit of the water in fuel sensor and a good ground. Turn the ignition ON, with the engine OFF. Does the water in fuel indicator illuminate in the driver information center?	Go to Step 3	Go to Step 4
3	Turn the ignition OFF. Connect a 3-ampere fused jumper wire between the signal circuit of the water in fuel sensor and the ground circuit of the water in fuel sensor. Turn the ignition ON, with the engine OFF. Does the water in fuel indicator illuminate in the driver information center?	Go to Step 9	Go to Step 6
4	Test the signal circuit of the water in fuel sensor for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 5
5	Install a scan tool. Turn the engine OFF. Disconnect the water in fuel sensor. Connect a 3 ampere fused jumper wire between the signal circuit of the water in fuel sensor and a good ground. Turn the ignition ON, with the engine OFF. With the scan tool, observe the Water In Fuel parameter in the PCM Engine Data 1 data list. Does the Water In Fuel parameter display On?	Go to Step 7	Go to Step 8
6	Test the ground circuit of the water in fuel sensor for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 9
7	Inspect for poor connections at the harness connector of the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 10
8	Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 11
9	Inspect for poor connections at the harness connector of the water in fuel sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 13	Go to Step 12
10	IMPORTANT: Program the replacement IPC. Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement .Did you complete the replacement?	Go to Step 13	-
11	IMPORTANT: Program the replacement PCM. Replace the PCM. Refer to the following: Engine Control Module (ECM) Replacement in Engine Controls - 6.6L (LB7) Engine Control Module (ECM) Replacement in Engine Controls - 6.6L (LLY) Did you complete the replacement?	Go to Step 13	-
12	Replace the water in fuel sensor. Refer to the following: Water-in-Fuel Sensor Replacement in Engine Controls - 6.6L (LB7) Water-in-Fuel Sensor Replacement in Engine Controls - 6.6L (LLY) Did you complete the replacement?	Go to Step 13	-
13	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2