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Fuel Gauge Inaccurate Or Inoperative

  1. Perform SYSTEM CHECK  . Go to next step.
  2. If fuel gauge is inoperative, go to next step. If fuel gauge works, go to step  4 .
  3. Install scan tool to DLC. See COMPONENT LOCATIONS  . Select SPECIAL FUNCTIONS from the INSTRUMENT PANEL CLUSTER MENU. Command fuel gauge from empty to full and back. If gauge responds as specified, go to step  5 . If gauge does not respond as specified, go to step  6 .
  4. If fuel gauge is inaccurate, go to step  7 . If fuel gauge is accurate, test is complete.
  5. Disconnect C400 connector. C400 is located under car near front of fuel tank. See Figure . Turn ignition switch to ON position. Use DVOM and measure voltage between ground and C400 terminal "C" (Blue/Black wire). If battery voltage is indicated, go to step  8 . If battery voltage is not indicated, go to step  9 .
  6. Replace and program the instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Go to SYSTEM CHECK  .
  7. Install scan tool to DLC. See COMPONENT LOCATIONS  . Select FUEL LEVEL GAUGE and ACTUAL FUEL LEVEL from data list. Wait for a minimum of 5 minutes for readings to stabilize. If both readings are approximately the same, go to SYSTEM CHECK  . If readings are different, go to step  10 .
  8. Turn ignition switch to OFF position. Use DVOM and measure resistance between ground and C400 terminal "B" (Black wire). If reading is 5 ohms or less, go to step  6 . If reading is greater than 5 ohms, go to step  11 .
  9. Locate and repair open in Blue/Black wire between C400 terminal "C" and instrument cluster terminal No. 20. See WIRING DIAGRAMS  . If circuit was repaired, go to SYSTEM CHECK  . If circuit is okay, go to step  6 .
  10. Connect a signal generator tool, an appropriate resistor or a potentiometer between C400 terminal "C" (Blue/Black wire) and ground. Ignition switch will need to be cycled off and on when a new resistance is value is used. Compare readings on scan tool and gauge with values in FUEL GAUGE VALUES  . If values are approximately the same, go to step  12 . If values are not even close, go to step  6 .
  11. Locate and repair excessive resistance in ground circuit for sending unit. After repair, go to SYSTEM CHECK  .
  12. Replace fuel sending unit. See FUEL TANK SENSOR under REMOVAL & INSTALLATION. Go to SYSTEM CHECK  .
FUEL GAUGE VALUES

Actual Gauge Reading Ohms Value Used (1) Scan Tool Display (Volts) Scan Tool Display (Gallons)
Full 42.7 1.7 18
3/4 82 3 12.5
1/2 116.5 3.9 9
1/4 176.8 5.1 4.5
Empty 272.4 6.2 0
(1) Approximate resistance value.
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