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Home >> Pontiac >> 2008 >> Torrent GXP, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 138 (Engine Controls And Fuel - 3.4L - Troubleshooting & Diagnosis) >> Fuel Pump Electrical Circuit Diagnosis >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the fuel pump relay.
  2. Ignition ON, verify that a test lamp illuminates between the ground circuit terminal 86 and B+.
    • If the test lamp does not illuminate, test the ground circuit terminal 86 for a short to voltage or an open/high resistance.
  3. Verify that a test lamp does not illuminate between the ground circuit terminal 86 and the control circuit terminal 85.
    • If the test lamp illuminates, test the control circuit terminal 86 for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Remove the test lamp.
  5. Command the fuel pump relay ON with a scan tool. Verify the scan tool fuel pump relay Ckt. Short Grnd Test Status parameter is OK.
    • If not the specified value, test the fuel pump relay control circuit terminal 85 for a short to ground. If the circuit tests normal, replace the ECM.
  6. Install a 3A fused jumper wire between the fuel pump relay control circuit terminal 85 and the ground circuit terminal 86. Command the fuel pump ON with a scan tool. Verify the scan tool fuel pump relay Ckt. Short Grnd Test Status parameter is Fault.
    • If not the specified value, test the fuel pump relay control circuit terminal 85 for an open/high resistance. If the circuit tests normal, replace the ECM.
  7. Inspect the fuel pump fuse.
    • If the fuel pump fuse is open, test for the following conditions:
      • A short to ground in the relay switch B+ circuit
      • A short to ground in the supply voltage circuit of the fuel pump
    • If the above circuits test normal, replace the fuel sender.
  8. Verify that a test light illuminates between the B+ circuit and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  9. Connect a 15A fused jumper wire between the B+ circuit and the supply voltage circuit of the fuel pump. Verify the fuel pump is activated.
    • If the fuel pump does not activate, test for the following conditions:
      • An open/high resistance in the supply voltage circuit of the fuel pump
      • An open/high resistance in the ground circuit of the fuel pump
    • If the above circuits test normal, replace the fuel sender.
  10. If all circuits test normal, test or replace the fuel pump relay.
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