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.
Circuit/System Testing
2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
- Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
- Ignition ON, verify the scan tool hood position parameter displays OPEN.
- If the hood position does not display OPEN, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
- With the ignition OFF, disconnect the harness connector at the FPCM.
- With the ignition ON, engine OFF, probe the control circuit of the fuel pump control module terminal 13 with a test lamp that is connected to a good ground. Command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF with each command.
- If the test lamp does not turn ON and OFF, test for an open, high resistance, or a short to ground in the fuel pump relay control circuit, an intermittent or a poor connection at the engine control module (ECM). If the circuit tests normal, replace the control module.
- If the test lamp remains illuminated with each command, test for a short to voltage in the control circuit of the fuel pump relay or an intermittent or a poor connection at the ECM. If the circuit tests normal, replace the control module.
- If all circuits test normal, replace the FPCM.
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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.