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Home › Hummer › 2008 › H2 4D Utility Pickup › Repair and Diagnosis › Engine Performance › System › Engine Controls And Fuel - 6.2L - DTC P1255 To DTC P2635 › DTC P2635 › Circuit/System Testing

Circuit/System Testing

IMPORTANT: Verify that DTC P0231, P0232, or P023F are not set as current or history before performing this diagnostic. If any of those codes are set as current or history, go to DTC P0231, P0232, or P023F .
  1. Ignition OFF, disconnect the harness connector at the fuel tank pump module.
  2. Ignition ON, test for 1.0 ohm or less between the fuel pump module low reference circuit terminal 2 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.
  3. Ignition OFF, disconnect the harness connector of the FPCM. Test for 1.0 ohm or less between the voltage supply circuit terminal 1 and the FPCM terminal 47.
    • If greater than the specified range, test the voltage supply circuit for a high resistance. If the circuit tests normal, replace the FPCM.
  4. If all circuits test normal, go to Symptoms - Engine Controls to check for any intermittent symptoms and ensure that the fuel pressure is normal. If there are no symptoms and the fuel pressure is normal, replace the fuel tank pump module.
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