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Home >> Chevrolet >> 2000 >> Tracker 4D Utility, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0450: Fuel Tank Pressure Sensor Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Turn ignition off. Remove fuel filler cap. Turn ignition on, with engine off. Observe fuel tank pressure sensor parameter on scan tool. If scan tool displays 0.0-0.5 in. H2 O (0.0-0.9 mm Hg), go to step  11. If scan tool does not display 0.0-0.5 in. H2 O (0.0-0.9 mm Hg), go to next step.
  3. Remove fuel tank. Remove fuel tank pressure sensor from fuel tank. Visually inspect fuel tank pressure sensor air vent hole and air pressure inlet passage for blockage. If blockage exists, go to step  13. If blockage does not exist, go to next step.
  4. Turn ignition on, with engine off. Disconnect fuel tank pressure sensor harness connector. Using DVOM, check voltage at fuel tank pressure sensor harness connector terminal No. 3 (reference voltage circuit). If voltage reading is 5 volts, go to step  6. If voltage reading is not 5 volts, go to next step.
  5. Check for an open in reference voltage circuit between fuel tank pressure sensor and PCM. Repair as necessary. After repairs, go to step  18. If circuit is okay, go to step  14.
  6. Using a test light connected to battery voltage, probe fuel tank pressure sensor harness connector terminal No. 2 (sensor ground circuit). If test light illuminates, go to step  8. If test light does not illuminate, go to next step.
  7. Check for an open in sensor ground circuit between fuel tank pressure sensor and PCM. Repair as necessary. After repairs, go to step  18. If circuit is okay, go to step  14.
  8. Select DC voltage scale on DVOM. Reconnect fuel tank pressure sensor harness connector. Using DVOM connected to ground, backprobe fuel tank pressure sensor harness connector terminal No. 1 (pressure input circuit). If voltage reading is 2.0-2.5 volts, leave DVOM connected and go to next step. If voltage reading is not 2.0-2.5 volts, go to step  15.
  9. Apply a small amount of vacuum to fuel tank pressure sensor while observing DVOM. If voltage drops, go to next step. If voltage does not drop, go to step  16.
  10. Check for an open in pressure input circuit between fuel tank pressure sensor and PCM. Repair as necessary. After repairs, go to step  18. If circuit is okay, go to step  14.
    11. WARNING: DO NOT breathe air through EVAP component tubes and hoses. Fuel vapors inside EVAP components may cause personal injury.
  11. Remove fuel tank pressure control valve. Blow air through valve from canister port (some resistance should be present). If air escapes from fuel tank port, go to next step. If air does not escape from tank port, go to step  17.
    12. NOTE: Fuel tank pressure control valve will not allow air to flow from tank side port to canister side port until pressure on tank side port exceeds.5 psi (.04 kg/cm2 ).
  12. Blow hard through fuel tank port of fuel tank pressure control valve. Air should escape from canister port. Apply 15 in. Hg of vacuum to vacuum port of fuel tank pressure control valve. With vacuum applied, blow gently through fuel tank port. Air should escape easily through canister port. If fuel tank pressure control valve operates as described, see DIAGNOSTIC AIDS . If fuel tank pressure control valve does not operate as described, go to step  17.
  13. Clean fuel tank pressure sensor air passages. After repairs, go to step  18.
  14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step  18.
  15. Check for a short in pressure input circuit between fuel tank pressure sensor and PCM. Repair as necessary. After repairs, go to step  18. If circuit is okay, go to next step.
  16. Replace fuel tank pressure sensor. After replacing fuel tank pressure sensor, go to step  18.
  17. Replace fuel tank pressure control valve. After replacing fuel tank pressure control valve, go to next step.
  18. After repairs, clear DTCs. Operate vehicle within FREEZE FRAME conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose DTC(s).
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