GM Service Manual Online
For 1990-2009 cars only

System Description

When an E85 compatible vehicle is built, an engine control module (ECM) or powertrain control module (PCM) replaced, or when the learned alcohol content has been reset with a scan tool the fuel system will need to contain ASTM gasoline with 10 percent or less ethanol content. If the fuel in the fuel system needs to be drained and replaced with ASTM gasoline, the engine will need to run at operating temperature and consume at least 1 liter of fuel before the system will recognize the correct alcohol content. Either ASTM gasoline or ASTM E85 fuel can then be used

Step

Action

Values

Yes

No

     

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Measure the ethanol content with a fuel sample from the fuel rail using the J 44175 Fuel Composition Tester .
  2. Compare the measured ethanol content to the fuel alcohol content parameter on the scan tool.

Is the difference between the measured ethanol content and the scan tool fuel alcohol content more than the specified value?

15%

Go to Step 3

Go to Step 8

3

Is the measured ethanol content less than the specified value?

15%

Go to Step 5

Go to Step 4

4

  1. Drain the Fuel Tank. Refer to Fuel Tank Draining .
  2. Important: A complete key cycle needs to occur when the fuel tank is drained to ensure the ECM/PCM recognizes a refueling event.

  3. Key ON, engine OFF for 10 seconds with drained fuel tank.
  4. Key OFF, add at least 11 liters (3 gallons) of gasoline containing 10% or less ethanol content.
  5. Important: At least 1 liter of fuel needs to be removed through the service port to ensure an accurate ethanol measurement of the fuel in the fuel system.

  6. Remove at least 1 liter of fuel from the service port into an approved container using the J 34730-1A or CH-48027 and the scan tool. Refer to Fuel Pressure Gage Installation and Removal .
  7. Measure the actual ethanol content with another fuel sample from the fuel rail using the J 44175 .

Is the measured ethanol content less than the specified value?

15%

Go to Step 5

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5

Use the scan tool to reset the learned fuel composition to the specified value.

Is the action complete?

3%

Go to Step 6

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6

Use the scan tool reset the fuel trim values.

Is the action complete?

--

Go to Step 7

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7

Important: The vehicle may need to be driven more than 11km (7 miles) with engine at operating temperature.

Operate the vehicle until the ethanol content has been learned and the Fuel Composition Learn parameter changes from Active to Inactive.

Is the action complete?

--

Go to Step 8

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8

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

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Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK