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Home >> Oldsmobile >> 2004 >> Bravada AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Engine Control System & Engine Component Tests - 2.2L) >> Fuel Systems >> Fuel Pump Electrical Circuit Test >> Diagnostic Procedures
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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L SONOMA & S10 PICKUP article. After performing diagnostic system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command fuel pump relay on and off. Repeat the commands as necessary. Does fuel pump turn on and off? If yes, problem is intermittent. If no, go to next step.
  3. Command fuel pump relay on and off with scan tool. Do you hear the fuel pump relay click when you command the fuel pump relay on and off? If yes, go to step  9. If no, go to next step.
  4. Turn ignition off. Remove fuel pump relay. Turn ignition on, with engine off. Using a test light connected to ground, probe the control circuit of the fuel pump relay. Using scan tool, command fuel pump relay on and off. Does the test light turn on and off? If yes, go to next step. If no, go to step  6.
  5. Connect test light between the control circuit of the fuel pump relay and ground circuit of the fuel pump relay. Command fuel pump relay on and off with scan tool. Does the test light turn on and off? If yes, go to step  19. If no, go to step  22.
  6. Does the test light remain illuminated with each command? If yes, go to next step. If no, go to step  8.
  7. Test the control circuit of the fuel pump relay for a short to voltage. Did you find and correct the condition? If yes, go to step  27. If no, go to step  26.
  8. Test the control circuit of the fuel pump relay for a short to ground or an open. Did you find and correct the condition? If yes, go to step  27. If no, go to step  20.
  9. Turn ignition on, with engine off. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step  11.
  10. Turn ignition off. Remove fuel pump relay. Turn ignition on, with engine off. Does the fuel pump operate continuously? If yes, go to step  21. If no, go to step  25.
  11. Inspect ECM "B" fuse. Is fuse open? If yes, go to next step. If no, go to step  14.
  12. Test the supply voltage circuit of the fuel pump for a short to ground between the ECM "B" fuse and fuel pump. Replace fuse, if necessary. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
  13. Connect all disconnected electrical components. Install a new ECM "B" fuse. Command fuel pump relay on with scan tool. Inspect ECM "B" fuse. Is fuse open? If yes, go to step  24. If no, problem is intermittent.
  14. Turn ignition off. Remove fuel pump relay. Turn ignition on, with engine off. Probe ignition 1 voltage circuit of the fuel pump relay (switch side) with test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  23.
  15. Connect a 20-amp fused jumper wire between the ignition 1 voltage circuit of the fuel pump relay and supply voltage circuit of the fuel pump. Does the fuel pump operate? If yes, go to step  19. If no, go to next step.
  16. Test the supply voltage circuit of the fuel pump for an open or high resistance between the fuel pump relay and fuel pump. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
    17. NOTE: Inspect ground circuit for correct tightness, corrosion on terminals, or damage to wiring harness.
  17. Test the fuel pump ground circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
  18. Test for an intermittent and for a poor connection at the fuel sender cover. Did you find and correct the condition? If yes, go to step  27. If no, go to step  24.
  19. Test for an intermittent and for a poor connection at the fuel pump relay. Did you find and correct the condition? If yes, go to step  27. If no, go to step  25.
  20. Test for an intermittent and for a poor connection at PCM. Did you find and correct the condition? If yes, go to step  27. If no, go to step  26.
  21. Repair short to voltage in the supply voltage circuit of the fuel pump. After repairs, go to step  27.
  22. Repair open or high resistance in the ground circuit of the fuel pump relay. After repairs, go to step  27.
  23. Repair open in the ignition 1 voltage circuit of the fuel pump relay. After repairs, go to step  27.
    24. NOTE: Inspect for poor connections at fuel pump, within the fuel tank, before replacing fuel pump.
  24. Replace fuel sender. Replace ECM "B" fuse, if necessary. After repairs, go to step  27.
  25. Replace fuel pump relay. After replacing relay, go to step  27.
  26. Replace PCM. See appropriate REMOVAL & INSTALLATION article. After replacing PCM, go to next step.
  27. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step  2.
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