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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 254 (Engine Control System & Fuel - 4.8L, 5.3L, 6.0L, Or 6.2L - DTC P069F To DTC P3449) >> DTC P2635 >> Circuit/System Testing

Circuit/System Testing

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  1. Verify that DTCs P0192, P0193, P0231, P0232, or P023F are not set as current or history.
  2. Ignition OFF, disconnect the harness connector at the fuel tank pump module.
  3. Ignition ON, test for less than 5.0 ohms 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 FPCM.
  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 with a scan tool. 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 FPCM.
    • 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 FPCM.
  6. Perform the Fuel System Diagnosis (w/o FPCM) or Fuel System Diagnosis (w/FPCM) to verify proper fuel pressure.
    • If the fuel pressure is not normal, replace the fuel tank fuel pump module.
  7. If all circuits test normal, replace the FPCM.
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