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Home >> Chevrolet >> 2006 >> Optra LS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 1.4L DOHC >> Diagnostic Information and Procedures >> DTC P0628 or P0629 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector of the fuel pump relay.
    2. IMPORTANT: The test lamp is used to load the circuit and may not illuminate.
  2. Connect a test lamp between the ignition 1 voltage circuit of the fuel pump relay and the negative terminal of the battery.
  3. Ignition ON, test for less than 0.1 volt between the ignition 1 voltage circuit of the fuel pump relay and the positive battery terminal.
    • If greater than 0.1 volt, repair the ignition 1 voltage circuit of the fuel pump relay for a short to ground or an open/high resistance.
  4. With the ignition OFF, connect a test lamp between the control circuit and the ignition 1 voltage circuit of the fuel pump relay.
  5. With the ignition ON, use a scan tool to command the fuel pump relay ON. The test lamp should turn ON for about 3-5 seconds and then turn OFF.
    • If the test lamp remains ON all the time, test for a short to ground on the control circuit. If circuit/connections test normal, replace the ECM.
    • If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.
  6. If all circuits/connections test normal, test or replace the fuel pump relay.
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