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Fuel Gauge Inoperative/Inaccurate

  1. Fuel level is displayed as a "filtered" fuel level measured in whole gallons (or liters). When IPC reads more than 18.9 gallons, it displays "F". All readings between 18.9 and 2 gallons will display in whole gallon numbers only. When IPC reads fuel level of 2.0 gallons, fuel gauge will display "E". When IPC reads fuel level of 1.0 gallon, "E" will flash and FUEL LEVEL VERY LOW message will display on DIC.
  2. If display is operating in DISPLAY OFF mode and fuel level falls to less than 4 gallons, all displays will illuminate and become active again. DIC will display CHECK FUEL GAUGE.
  3. Enter self-diagnostics and record all codes. See ENTERING SELF-DIAGNOSTICS  under SELF-DIAGNOSTICS. If Code I041 is set, see CODE I041 OR I042 - BATTERY VOLTAGE TOO LOW OR TOO HIGH. If Code I041 is not set and fuel gauge operation is nonlinear or erratic, go to next step. If Code I041 is not set and fuel gauge always reads full, go to step 5). If Code I041 is not set and fuel gauge always reads empty, go to step 8).
  4. Ensure all related terminal connections are good. Exit self-diagnostics. Remove fuel tank sending unit. If connector was disconnected during removal, reconnect sending unit to its harness connector, near filler tube on top of tank. Enter diagnostics to observe ID40 data value. Hand operate fuel sending unit float through full range of travel, watching for jumps or erratic data values. If sending unit does not move freely and/or data values jump, replace sending unit.
  5. Note data value of ID40 (fuel level). If data value reading is of actual gallons in tank and is much different than IPC fuel gauge display, replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION. If data value reading is 16 or more gallons, disconnect fuel tank sending unit connector.
  6. If data value reading is now less than 2 gallons, go to next step. If data value reading is now 2 gallons or more, repair short to voltage in Purple wire circuit. If a short is not found, replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION.
  7. Use DVOM to measure voltage at fuel sending unit harness connector between terminals "D" (Pink wire) and "F" (Black/White wire). If voltage is 10 volts or greater, replace sending unit. If voltage is less than 10 volts, repair open in Black/White wire from terminal "F" to ground.
  8. Note data value of ID50 (ignition voltage to IPC reading). If voltage is less than 2 volts, repair open or short to ground in Pink wire from White IPC connector terminal C13 to engine compartment fuse block fuse A3. See Fig 1 . If voltage is 2-10 volts, ensure good terminal connections at IPC connector C1 terminal C13 and repair charging system problem.
    Fig 1: Identifying IPC Harness Connector Terminals
    G92D05240Courtesy of GENERAL MOTORS CORP.
  9. If voltage is 10 volts or more, note data value of ID40 (fuel level). If value is same as actual fuel level in tank (with more than 3 gallons in tank), replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION. If value is less than 3 gallons, go to next step.
  10. Turn ignition on, close all doors and turn radio on. With doors still closed, turn off ignition. If radio continues to play, go to step 12). If radio turns off, go to next step.
  11. Repair open in power feed circuit (Pink wire) to Retained Accessory Power (RAP) module and fuel tank sending unit between splice S402 and trunk fuse block fuse A11. Splice S402 is located vertically behind left side of rear seat back, inside black tape wrapped harness, about 10 inches below top of cross panel. This is not "flat" type harness cover going into trunk. Splice S402 wire color is Pink.
  12. Turn ignition on. Using DVOM, measure voltage between fuel sending unit harness connector terminals "D" (Pink wire) and "F" (Black/White wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, repair open in Pink wire from splice S402 to fuel sending unit connector. See previous step for location of splice S402.
  13. Use a jumper wire to connect fuel sending unit harness connector terminals "D" (Pink wire) and "E" (Purple wire). Note data value of ID40. If value is greater than 3 gallons, replace fuel sending unit. If value is less than 3 gallons, go to next step.
  14. Measure voltage between IPC connector terminal C8 and ground. See Fig 1 . If voltage is less than 10 volts, repair open or short to ground in Purple wire between IPC and fuel sending unit harness connector terminal "E". If voltage is 10 volts or greater, check terminal contact. If contact is okay, replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION.
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