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Fuel Gauge Inaccurate Or Inoperative: Testing

  1. If instrument cluster diagnostic system check was performed, go to next step. If instrument cluster diagnostic system check was not performed, go to INSTRUMENT CLUSTER DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Disconnect 7-pin connector C420. C420 is located under right rear of vehicle, near wheelwell. See Figure . Connect Signal Generator (J33431-C) and Instrument Panel Tester between connector C420 terminals "A" (Purple wire) and "D" (Black/White wire). See Figure . Turn ignition on. Vary resistance on Signal Generator from 40-250 ohms. See FUEL LEVEL SPECIFICATIONS  table to convert from resistance to fuel gauge reading. If fuel gauge does not display correct fuel level, go to next step. If fuel gauge displays correct fuel level, go to step  4 .
  3. Turn ignition off. Connect scan tool to Data Link Connector (DLC). See Figure . Turn ignition on. Vary resistance on Signal Generator from 40-250 ohms. See FUEL LEVEL SPECIFICATIONS  table to convert from resistance to fuel level in percent. Turn ignition off between resistance settings to update scan tool display. Using scan tool, select PCM ENHANCED EVAP data list. Monitor FUEL LEVEL % status. If FUEL LEVEL % status does not match conversion, go to step  5 . If FUEL LEVEL % status matches conversion, go to step  11 .
  4. Check for poor connection at fuel level sender connector, high resistance in Purple or Black/White wire between fuel level sender and C420, misaligned fuel level sender or a deformed fuel tank. If connections, circuits and components are okay, go to step  7 . If fault was found and repaired, go to step  13 .
  5. Check for high resistance in Purple wire between connector C420 and Powertrain Control Module (PCM) connector C2 terminal No. 72. See Figure . If circuit is okay, go to next step. If faulty circuit is found and repaired, go to step  13 .
  6. Check for high resistance in Black/White wire between connector C420 and PCM connector C2 terminal No. 13. If circuit is okay, go to step  9 . If faulty circuit is found and repaired, go to step  13 .
  7. Remove fuel level sender. See FUEL LEVEL SENDER  under REMOVAL & INSTALLATION. Check for stuck fuel level sender, fuel strainer interfering with sender float arm or foreign material in fuel tank. If sending unit and fuel tank are okay, go to next step. If fault was found and repaired, go to step  13 .
  8. Using DVOM, measure resistance between connector C420 terminals "A" (Purple wire) and "D" (Black/White wire) while moving the float arm. Monitor DVOM reading. If resistance changes smoothly from 40-250 ohms, go to DIAGNOSTIC AIDS  . If resistance does not change smoothly from 40-250 ohms, go to step  10 .
  9. Check for poor connections at PCM connector. If connections are okay, go to step  12 . If faulty connections are found and repaired, go to step  13 .
  10. Replace fuel level sender. See FUEL LEVEL SENDER  under REMOVAL & INSTALLATION. After repairs, go to step  13 .
  11. Replace Instrument Panel Cluster (IPC). See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION. After repairs, go to step  13 .
  12. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After repairs, go to step  13 .
  13. After repairs, recheck operation of gauge. If gauge operates properly, repair is complete. If gauge does not operate properly, go to step  2 .
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