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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 941 (Engine Controls And Fuel - 4.8L, 5.3L, 6.0L And 6.2L - DTC P1380 To DTC P3449) >> DTC P3401, P3425, P3441, or P3449 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 GMC Sierra, 2007 GMC Cab & Chassis Sierra, 2007 Chevrolet Silverado, and 2007 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
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 (With CH 48027) or Fuel Pressure Relief (Without CH 48027) .
  3. Remove the Intake Manifold.
  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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