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Home >> Pontiac >> 2001 >> Aztek Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Fuel System (CNG) >> Fuel Gauge Selector Switch/Fuel Indicator Light
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Fuel Gauge Selector Switch/Fuel Indicator Light

  1. Perform OBD system check. See ON BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. Go to next step.
  2. Turn ignition off for 30 seconds. Turn ignition on. Fuel Indicator Light (FIL), located on fuel gauge select switch should illuminate for 2 seconds (bulb check), then turn off. If FIL does not operate as specified, go to next step. If FIL operates as specified, go to step  9.
  3. If FIL stays on, go to next step. If FIL does not illuminate, go to step  6.
  4. Using scan tool, command AF ECU to turn FIL off. If FIL turns off, go to next step. If FIL does not turn off, go to step  8.
  5. Find cause of gasoline operation. Check for empty CNG tank, inaccurate fuel pressure sensor or AF ECU DTC. Repair as necessary. After repairs, go to step  22.
  6. Turn on instrument panel lights. Check fuel gauge select switch illumination. If illumination is okay, go to next step. If switch illumination does not work, go to step  11.
  7. Turn off instrument panel lights. Remove fuel gauge select switch. Disconnect 6-pin switch connector C239. Connect test light between harness connector terminals "D" (Purple wire) and "E" (Black wire). Turn ignition off for 30 seconds. Turn ignition on. If test light does not illuminate, go to step  12. If test light illuminates, go to step  20.
  8. Turn ignition off for 30 seconds. Disconnect AF ECU connectors. Turn ignition on. If FIL illuminates, go to step  16. If FIL does not illuminate, go to step  21.
  9. Connect scan tool. Using scan tool, monitor fuel gauge select switch input data. Press and release fuel gauge select switch. If scan tool data changed, go to next step. If scan tool data did not change, go to step  13.
  10. If fuel gauge is okay, test is complete. If fuel gauge is inaccurate or inoperative, check fuel gauge relay. See FUEL GAUGE RELAY .
  11. Remove fuel gauge select switch. Disconnect 6-pin switch connector C239. Connect test light between battery voltage and harness connector terminal "E" (Black wire). Turn ignition on. If test light does not illuminate, go to step  17. If test light illuminates, go to step  20.
  12. Turn ignition off for 30 seconds. Disconnect AF ECU connectors. Check for open on Brown wire between fuel gauge select switch harness connector C239 terminal "C" and AF ECU connector C002 terminal No. 14. If open exists, go to step  18. If circuit is okay, go to step  21.
  13. Remove fuel gauge select switch. Disconnect 6-pin switch connector C239. Connect test light between harness connector C239 terminal "A" (Red wire) and ground. Turn ignition on. If test light illuminates, go to next step. If test light does not illuminate, go to step  19.
  14. Using scan tool, monitor fuel gauge select switch input data. Connect a fused jumper wire between harness connector C239 "A" (Red wire) and "C" (Brown wire). If scan tool data did not change, go to next step. If scan tool data changed, go to step  20.
  15. Turn ignition off for 30 seconds. Disconnect AF ECU connectors. Check for open, short to voltage or poor contact on Brown wire between fuel gauge select switch harness connector C239 terminal "C" and AF ECU connector C002 terminal No. 14. If no problem is found, go to step  21. If any problem is found, repair as necessary. After repairs, go to step  22.
  16. Replace internally shorted switch or repair short to power on Brown wire between fuel gauge select switch harness connector C239 terminal "C" and AF ECU connector C002 terminal No. 14. After repairs, go to step  22.
  17. Repair open circuit on Black wire between fuel gauge select switch harness connector C239 terminal "E" and ground. After repairs, go to step  22.
  18. Repair open or poor contact on Purple wire between fuel gauge select switch harness connector C239 terminal "D" and AF ECU connector C001 terminal No. 31. After repairs, go to step  22.
  19. Repair open on Red wire (power supply) at fuel gauge select switch harness connector C239 terminal "A". See WIRING DIAGRAMS article. After repairs, go to step  22.
  20. Replace fuel gauge select switch. After repairs, go to step  22.
  21. Replace AF ECU. After repairs, go to next step.
  22. Reconnect all components and connectors. Using scan tool, clear all DTCs. Turn ignition off for 30 seconds. Start engine. Test drive vehicle. If no problems are found, MIL operates properly and no DTCs are set, test is complete. If any problems are found, MIL does not operate properly or DTCs are set, perform OBD system check. See ON BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.
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