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Home >> Buick >> 2012 >> Enclave AWD >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls/Fuel - 3.6L - DTC P0340 To DTC P2635 And Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> DTC P2635 (Fuel Pump Control Module) >> Circuit/System Testing

Circuit/System Testing

NOTE:

Do not replace the fuel pump control module based on a history DTC P2635. The DTC P2635 may be stored but that does not indicate a failure of the fuel pump control module. Refer to Strategy Based Diagnosis for further history DTC diagnostics.

NOTE:

Verify that DTCs P018B, P018C, P018D, P0231, P0232, or P023F are not set as current or history before performing this diagnostic. If any of those codes are set as current or history, refer to DTC P018B-P018D , or DTC P0231, P0232, or P023F .

  1. Ignition OFF, disconnect the harness connector at the fuel tank pump module.
  2. Ignition ON, test for 5.0 Ω or less between the fuel pump module low reference circuit terminal 2 and ground.
    • If greater than the specified range, test the fuel pump module low reference circuit for a high resistance. If the circuit tests normal, replace the fuel pump control module.
  3. Ignition OFF, install a test lamp between the control circuit terminal 1 and the control circuit terminal 2.
  4. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the fuel pump control module.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fuel pump control module.
  5. Perform the Fuel System Diagnosis  to verify proper fuel pressure.
    • If the fuel pressure is not normal, replace the fuel tank fuel pump module.
  6. If the fuel system components test normal, refer to Symptoms - Engine Controls .
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