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Home >> Chevrolet >> 2007 >> Chevy Express G2500, Van Cargo, 6.6 6 >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Engine Control System & Fuel System - 6.6L (LLY) - Troubleshooting & Diagnosis) >> Fuel Pump Electrical Circuit Diagnosis >> Circuit/System Testing

Circuit/System Testing

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  1. Inspect the fuel pump fuse.
    • If the fuel pump fuse is open, test the battery positive voltage circuit and the fuel pump supply voltage circuit for a short to ground or a faulty fuel pump.
  2. Turn ON the ignition, with the engine OFF.
  3. Command the fuel pump ON and OFF with a scan tool. The fuel pump relay should click and turn ON and OFF with each command.
    • If the fuel pump operates continuously, test for a faulty relay or a short to voltage in the fuel pump supply voltage circuit.
    • If the fuel pump does not turn ON and OFF, replace the fuel pump relay.
  4. Probe the battery positive voltage circuit of the fuel pump relay with a test lamp that is connected to a good ground.
    • If the test lamp does not illuminate, repair the open in the battery positive voltage circuit.
  5. Connect a fused jumper wire between the battery positive voltage circuit and the supply voltage circuit of the fuel pump relay.
    • If the fuel pump operates, test for an intermittent and for a poor connection at the fuel pump relay, or a faulty fuel pump relay.
    • If the fuel pump does not operate, test for an open or high resistance in the supply voltage circuit, or ground circuit of the fuel pump.
    • If all circuits test normal and the fuel pump relay operates properly, replace the DFCM housing containing the fuel pump.
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