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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 249 (ENGINE CONTROLS - BASIC DIAGNOSTIC PROCEDURES)FUEL SYSTEMFUEL PUMP ELECTRICAL CIRCUIT DIAGNOSISDIAGNOSTIC PROCEDURE
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Diagnostic Procedure

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Diagnostic Procedure
WARNING: This page is about a different car, the 2003 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For terminal and circuit identification, see WIRING DIAGRAMS  .
  1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.0L AURORA article.
  2. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump relay turns on and off as commanded, no problem is indicated at this time. Fault may be intermittent. If fuel pump relay does not turn on and off as commanded, go to next step.
  3. Using scan tool, command fuel pump relay on and off. Listen for fuel pump relay operating click noise. Fuel pump relay is located in rear fuse block. Rear fuse block is located underneath driver's side rear seat. See Fig 1 . If fuel pump relay operating noise is heard as relay is commanded on and off, go to step  9 . If fuel pump relay operating noise is not heard as relay is commanded on and off, go to next step.
  4. Turn ignition off. Remove fuel pump relay. See Fig 1 . Turn ignition on. Using a test light connected to ground, probe fuel pump relay control circuit at fuel pump relay connector in rear fuse block. Using scan tool, command fuel pump relay on and off. If test light turns on and off as commanded, disconnect test light and go to next step. If test light does not turn on and off as commanded, go to step  6 .
  5. Turn ignition off. Connect a test light between fuel pump relay control circuit and fuel pump relay ground circuit at fuel pump relay connector in rear fuse block. Turn ignition on. Using scan tool, command fuel pump relay on and off. If test light turns on and off as commanded, go to step  21 . If test light does not turn on and off as commanded, go to step  24 .
  6. If test light is always on, go to next step. If test light is always off, go to step  8 .
  7. Test the fuel pump relay control circuit 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 the fuel pump relay control circuit 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. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step  11 .
  10. Turn ignition off. Remove fuel pump relay. If fuel pump still runs continuously, go to step  23 . If fuel pump does not run continuously, go to step  27 .
  11. Inspect F/PMP fuse (20-amp). See Fig 1 . If fuse is blown, go to next step. If fuse is okay, go to step  14 .
  12. Disconnect the fuel pump harness in-line connector located near the fuel tank. Test the supply voltage circuit of the fuel pump for a grounded circuit. See Fig 2 . Replace the 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. Check for damaged or shorted fuel pump wiring harness. Fuel pump can be accessed through an inspection panel in trunk. To inspect complete wiring harness, if may be necessary to lower fuel tank. 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. Remove fuel pump relay. See Fig 1 . Turn ignition on. Using a test light connected to ground, probe voltage supply circuit at fuel pump relay connector in rear fuse block. If test light illuminates, go to next step. If test light does not illuminate, go to step  25 .
  15. Connect a 20-amp fused jumper wire between the switch voltage circuit and the fuel pump supply circuit in the fuel pump cavity. If fuel pump operates, go to step  21 . If fuel pump does not operate, go to next step.
  16. Disconnect fuel pump harness in-line connector located near right side of fuel tank. Check for an open or high resistance between fuel pump relay connector in rear fuse block and fuel pump harness in-line connector. Did you find and correct the condition? If yes, go to step  29 . If no, go to next step.
    17. NOTE: Inspect the ground circuit for being tight, corrosion on the terminals, or damage to the wiring harness.
  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. Test for an intermittent and a poor connection 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. Check for damaged or open fuel pump wiring harness. Fuel pump can be accessed through an inspection panel in trunk. To inspect complete wiring harness, if may be necessary to lower fuel tank. Did you find and correct the condition? If yes, go to step  29 . If no, go to step  26 .
  20. Reconnect all components. Install a new F/PMP fuse. Using scan tool, command fuel pump on. Recheck F/PMP fuse. If fuse is blown, go to step  26 . If fuse is okay, no problem is indicated at this time. Fault may be intermittent.
  21. Check fuel pump relay connector for poor connections. Did you find and correct the condition? If yes, go to step  29 . If connector is okay, go to step  27 .
  22. Check PCM connectors for poor connections. PCM is located in engine compartment, inside air filter housing. Did you find and correct the condition? If yes, go to step  29 . If connectors are okay, go to step  28 .
  23. Repair short to voltage in fuel pump supply circuit between fuel pump and fuel pump relay. After repairs, go to step  29 .
  24. Repair open in fuel pump relay ground circuit. After repairs, go to step  29 .
  25. Repair open in voltage supply circuit to fuel pump relay. After repairs, go to step  29 .
  26. Check fuel pump connector for poor connections. Repair connector as necessary. If connector is okay, replace fuel pump. After repairs, go to step  29 . Replace F/PMP fuse, if necessary.
  27. Replace fuel pump relay. After repairs, go to step  29 .
  28. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - AURORA article. After repairs, go to next step.
  29. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. If engine starts and continues to idle, system is okay. If engine does not start or continue to idle, go to step  2 .
Fig 1: Locating Fuel Pump Relay
G00232263Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

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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.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • 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.