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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 127 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING)FUEL SYSTEMSFUEL PUMP ELECTRICAL CIRCUIT DIAGNOSISDIAGNOSTIC PROCEDURES
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Diagnostic Procedures

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. 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 - 3.4L AZTEK & RENDEZVOUS article. After performing diagnostic system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command the fuel pump relay ON and OFF. Does the fuel pump turn ON and OFF? If yes, problem is intermittent. If yes, go to next step.
  3. Using scan tool, command fuel pump relay ON and OFF. Do you hear a 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. Disconnect fuel pump relay, located in underhood fuse/relay block. Turn ignition on, with engine off. Probe control circuit of the fuel pump relay with a test light that is connected to a good ground. See Figure . With scan tool, command the fuel pump 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 the test light between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay. With a scan tool, command the fuel pump ON and OFF. Does test light turn ON and OFF? If yes, go to step  21 . If no, go to step  24 .
  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  29 . If no, go to step  28 .
  8. Test 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  29 . If no, go to step  22 .
  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. Disconnect fuel pump relay, located in underhood fuse/relay block. Turn ignition on, with engine off. Does the fuel pump operate continuously? If yes, go to step  23 . If no, go to step  27 .
  11. Is the fuel pump fuse open? If yes, go to next step. If no, go to step  14 .
  12. Disconnect the fuel pump harness in-line connector, located near fuel tank. Test the fuel pump supply voltage circuit for a short to ground. See Figure . Replace fuel pump fuse, if necessary. Did you find and correct the condition? If yes, go to step  29 . If no, go to next step.
  13. Lower fuel tank, if necessary. Test or inspect the fuel tank electrical harness for damage or grounded circuit. Replace the fuel pump fuse, if necessary. Did you find and correct the condition? If yes, go to step  29 . If no, go to step  20 .
  14. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the battery positive voltage circuit of the fuel pump relay with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  25 .
  15. Connect a 10-amp fused jumper wire between the battery positive voltage circuit and fuel pump supply voltage circuit in the fuel pump cavity. Does the fuel pump operate? If yes, go to step  21 . If no, go to next step.
  16. Disconnect the fuel pump harness in-line connector located near the fuel tank. Test the fuel pump supply voltage circuit for an open or high resistance between the fuel pump relay and the in-line connector. Did you find and correct the condition? If yes, go to step  29 . If no, go to next step.
  17. Test the ground circuit of the fuel pump for an open or high resistance between the body pass-through connector and the ground. Did you find and correct the condition? If yes, go to step  29 . If no, go to next step.
  18. Inspect for poor connections at the fuel pump in-line connector to the body pass-through connector. Did you find and correct the condition? If yes, go to step  29 . If no, go to next step.
  19. Lower fuel tank. Test or inspect the fuel tank electrical harness for damage or open circuit. Did you find and correct the condition? If yes, go to step  29 . If no, go to step 26.
  20. Connect all disconnected components. Install a new fuel pump fuse. With a scan tool, command the fuel pump ON. Is the fuel pump fuse open? If yes, go to step  26 . If no, problem is intermittent.
  21. Inspect for poor connections at the fuel pump relay. Did you find and correct the condition? If yes, go to step  29 . If no, go to step  27 .
  22. Inspect for poor connections at PCM harness. Did you find and correct the condition? If yes, go to step  29 . If no, go to step  28 .
  23. Repair fuel pump supply voltage circuit for a short to voltage. After repairs, go to step  29 .
  24. Repair fuel pump relay ground circuit for an open ground. After repairs, go to step  29 .
  25. Repair battery positive voltage circuit of the fuel pump relay for an open. After repairs, go to step  29 .
  26. Replace fuel pump. After replacing fuel pump, go to step  29 .
  27. Replace fuel pump relay. After replacing relay, go to step  29 .
  28. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM programing. After replacing PCM, go to next step.
  29. 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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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.