Diagnostic Procedures

1999 Chevrolet Cutaway 7.4 JSECTION Diagnostic Procedures
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, check for DTCs. If DTCs P0462 or P0463 are set, diagnose these DTCs first. If DTCs P0462 and P0463 are not set, go to next step.
  3. Turn ignition off. Disconnect fuel level sensor harness connector. Turn ignition on, with engine off. Using scan tool, monitor fuel level. If value is 100 percent, go to next step. If value is not 100 percent, go to step  5.
  4. Using a fused jumper wire, jumper fuel level sensor signal and ground circuits together at harness connector. Using scan tool, monitor fuel level sensor. If value is zero percent, go to step  10. If value is not zero percent, go to step  6.
  5. Check fuel level sensor circuit for a short to ground. Repair as necessary. After repairs, go to step  12. If circuit is okay, go to step  9.
  6. Using a test light connected to battery positive, probe ground circuit at fuel level sensor harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  8.
  7. Check fuel level sensor signal circuit for an open or poor connection. Repair as necessary. After repairs, go to step  12. If circuit is okay, go to step  9.
  8. Check fuel level sensor ground circuit at PCM harness connector for an open or poor connection. Repair as necessary. After repairs, go to step  12. If circuit is okay, go to next step.
  9. Replace PCM. Program replacement PCM using required equipment. After repairs, go to step  12.
  10. Check for faulty fuel level sensor harness connection. Repair as necessary. After repairs, go to step  12. If connections are okay, go to next step.
  11. Replace fuel level sensor. After repairs, go to next step.
  12. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step  2.
  13. Using scan tool, display CAPTURE and REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no additional DTCs are displayed, system is okay.
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When to See a Mechanic

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.