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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 145 (Engine Control System & Fuel - 4.8L, 5.3L, 6.0L And 6.2L - DTC P0335 To DTC P3449) >> DTC P3401, P3425, P3441, or P3449 >> Circuit/System Testing

Circuit/System Testing

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IMPORTANT: Perform the Circuit/System Verification  first.
  1. Ignition OFF, remove the fuel pump fuse or the fuse for the fuel system control module.
  2. Perform the Fuel Pressure Relief .
  3. Remove the Intake Manifold. Refer to Intake Manifold Removal (RPO LY2/LY6) or Intake Manifold Removal (RPO LC9/LY5/LMG/L76) or Intake Manifold Removal (RPO L92) .
  4. Disconnect the VLOM harness connector.
  5. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal E, and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the VLOM assembly.
  6. Connect a test lamp between the appropriate control circuit terminal and the ignition circuit terminal E.
  7. Command the VLOM solenoid 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 ground. If the circuit test normal, replace the ECM.
    • If the test lamp is always OFF, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.
  8. If all circuits test normal, test or replace the VLOM assembly.
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