Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 108 (ENGINE CONTROLS SELF-DIAGNOSTICS - 2.2L BI-FUEL)DIAGNOSTIC TESTSDTC P0148: ALTERNATIVE FUEL ENABLE CONTROL CIRCUITTEST DESCRIPTION
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6
Test Description
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Test Description
WARNING: This page is about a different car, the 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers in the diagnostic procedure.
- 2 - This step determines if the condition is active.
- 4 - This step determines if the PCM can control the AF relay. Command the relay ON and OFF several times to verify AF relay operation.
- 5 - This step tests the voltage circuit to the AF relay coil. If the test light illuminates the circuit is okay.
- 6 - This step tests the AF enable output circuit from the PCM. The test light should turn ON and OFF with each command.
- 7 - This step determines if a ground is constantly applied to the AF enable output circuit.
- 10 - This step tests the voltage circuit to the AF relay switch. If the test light illuminates, the circuit is okay. If the test light does not illuminate, a short to ground may be the cause of the condition. If the AF relay fuse is open, test all of the related switch circuits.
- 11 - This step tests the AF enable signal circuit from the AF relay to the FICM. The test light should turn ON and OFF using the scan tool commands.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.