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 MANUALSCHEVROLET2012CHEVY EXPRESS G2500, VAN PASSENGER, 4.8L ENG VIN AREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 2107 (ENGINE CONTROLS AND FUEL - HYBRID (LZ1) - DTC P0351 THROUGH DTC P3449 AND TROUBLESHOOTING)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P2635 (FUEL PUMP CONTROL MODULE)CIRCUIT/SYSTEM TESTING
2012 Chevrolet Chevy Express G2500, Van Passenger, 4.8L Eng VIN A
Circuit/System Testing
2012 Chevrolet Chevy Express G2500, Van Passenger, 4.8L Eng VIN ASECTION Circuit/System Testing
WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
- Verify that DTCs P018B, P018C, P018D, P0231, P0232, or P023F are not set.
- If the DTCs are set, refer to DTC P018B-P018D , or DTC P0231, P0232, or P023F .
- Ignition OFF, disconnect the harness connector at the fuel tank pump module.
- Ignition ON, test for less than 5.0 Ξ© between the fuel pump module low reference circuit terminal A and ground.
- If greater than the specified range, test the fuel pump module low reference circuit for a high resistance. If the circuit tests normal, replace the fuel pump control module.
- Ignition OFF, install a test lamp between the control circuit terminal D and the control circuit terminal A.
- Ignition ON, command the fuel pump ON and OFF using a scan tool ECM fuel pump output control. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the fuel pump control module.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fuel pump control module.
- If all circuits test normal, perform the Fuel System DiagnosisΒ to verify proper fuel pressure.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.