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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1646 (Engine Control System & Fuel System - 4.8L, 5.3L, 6.0L, 6.2L - Troubleshooting And Diagnosis) >> Fuel Pump Electrical Circuit Diagnosis (with FPCM) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the G12 fuel pump.
  2. Connect a test lamp between the control circuit terminal D and ground.
  3. Ignition ON, command the G12 fuel pump ON and OFF using a scan tool ECM fuel pump output control. The test lamp should turn ON and OFF, as commanded.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K27 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 K27 fuel pump control module.
  4. Ignition OFF, connect a test lamp between the control circuit terminal D and the low reference circuit terminal A.
  5. Ignition ON, command the G12 fuel pump ON using a scan tool. The test lamp should illuminate.
    • If the test lamp does not illuminate, test the low reference circuit terminal D for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K27 fuel pump control module.
  6. If all circuits test normal, replace the G12 fuel pump.
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