Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Buick >> 2008 >> Allure CXS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 3.6L - DTC P0335 To DTC P2097 >> DTC P0627, P0628, or P0629 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the fuel pump relay.
  2. Connect a test lamp between the control circuit of the fuel pump relay and ground.
  3. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF as commanded.
    • If the test lamp remains OFF all the time, test for a short to ground or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.
    • If the test lamp remains ON all the time, test for a short to voltage on the control circuit. If circuit/connections test normal, replace the ECM.
  4. Ignition OFF, connect a test lamp between the fuel pump relay control circuit and the ground circuit of the fuel pump relay.
  5. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF as commanded.
    • If the test lamp does not turn ON when commanded, repair the open/high resistance in ground circuit of the fuel pump relay.
  6. If all circuits/connections test normal, test or replace the fuel pump relay.
scientia non olet · About Mike's Workshop Manuals