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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 365 (Engine Controls And Fuel - Hybrid (LZ1) - DTC P0351 Through DTC P3449 And Troubleshooting) >> Diagnostic Information and Procedures >> DTC P2635 (Fuel Pump Control Module) >> Circuit/System Testing

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.
  1. Verify that DTCs P018B, P018C, P018D, P0231, P0232, or P023F are not set.
  2. Ignition OFF, disconnect the harness connector at the fuel tank pump module.
  3. Ignition ON, test for less than 5.0 Ω 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.
  4. Ignition OFF, install a test lamp between the control circuit terminal D and the control circuit terminal A.
  5. 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.
  6. If all circuits test normal, perform the Fuel System Diagnosis  to verify proper fuel pressure.
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