GM Service Manual Online
For 1990-2009 cars only

Diagnostic Aids

    • The water in fuel sensor illuminates the water in fuel indicator 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 in Engine Controls - 6.6L (LB7).
       -  Water-in-Fuel Draining in Engine Controls - 6.6L (LLY).
       -  Water-in-Fuel Draining in Engine Controls - 7.8L.
    • For intermittent diagnosis, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Step

Action

Yes

No

Schematic Reference: Driver Information System Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Diagnostic System Check - Instrument Cluster?

Go to Step 2

Go to Diagnostic System Check - Instrument Cluster

2

  1. Start and idle the engine.
  2. Observe the water in fuel indicator in the message center.

Does the water in fuel indicator illuminate in the message center?

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn the engine OFF.
  2. Disconnect the water in fuel sensor.
  3. Start and idle the engine.
  4. Observe the water in fuel indicator in the message center.

Does the water in fuel indicator illuminate in the message center?

Go to Step 4

Go to Step 6

4

Test the signal circuit of the water in fuel sensor for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 5

5

Inspect for poor connections at the harness connector of the message center. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

6

Inspect for poor connections at the harness connector of the water in fuel sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

7

Replace the message center. Refer to Telltale Circuit Board Replacement .

Did you complete the replacement?

Go to Step 9

--

8

Replace the water-in-fuel sensor. Refer to:

    •  Water in Fuel Indicator Sensor Replacement in Engine Controls - 6.6L (LB7).
    •  Water in Fuel Indicator Sensor Replacement in Engine Controls - 6.6L (LLY).
    • Water in Fuel Sensor Replacement in Engine Controls - 7.8L.

Did you complete the replacement?

Go to Step 9

--

9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2