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Home >> Suzuki >> 1991 >> Samurai JS >> Repair and Diagnosis >> External Pages >> Different car >> Section 33 (Engine General Information And Diagnosis) >> Diagnostic Information and Procedures >> DTC P0627, P0628, or P0629 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
  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. Ignition ON, test for 2-3 volts on the control circuit of the fuel pump relay.
    • If the voltage is not within the specified range, replace the ECM.
  7. If all circuits/connections test normal, test or replace the fuel pump relay.
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