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.
- Ignition OFF, remove the fuel pump fuse or the fuse for the fuel system control module.
- Perform the Fuel Pressure Relief (With CH 48027) or Fuel Pressure Relief (Without CH 48027) .
- Remove the Intake Manifold.
- Disconnect the VLOM harness connector.
- 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.
- Connect a test lamp between the appropriate control circuit terminal and the ignition circuit terminal E.
- 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.
- If all circuits test normal, test or replace the VLOM assembly.