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Home >> Mitsubishi >> 2001 >> Montero Limited >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0450: EVAP System Pressure Sensor Malfunction >> Diagnostic Procedure

Diagnostic Procedure

  1. Remove fuel cap. Turn ignition on. Using scan tool, check data list item No. 73 (fuel tank pressure differential sensor). Scan tool pressure reading should be -1.5-1.5 kPa. Connect Miller EVAP System Pressure Pump (6872A) to fuel filler neck and apply pressure. Scan tool reading should increase. If readings are not as specified, go to next step. If readings are as specified, go to step  13.
  2. Turn ignition off. Tilt up second seat and access service hole in floor. Remove service hole upper and lower covers and packing. Disconnect FTDP sensor 3-pin connector. Check FTDP sensor connector for loose, damaged, or corroded terminals. If problem exists, repair connector, then go to step  22. If problem does not exist, go to next step.
  3. Turn ignition on. Measure voltage between ground and FTDP sensor connector terminal No. 3 (Green/Red wire). See Figure. Voltage should be 4.8-5.2 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step  8.
  4. Turn ignition off. Check for continuity between ground and FTDP sensor connector terminal No. 2 (Black wire). If continuity exists, go to next step. If continuity does not exist, go to step  11.
    NOTE: For next step, manufacturer recommends using Special Tool (MB991658) test harness connected between FTDP sensor connector halves instead of jumper wires.
  5. Using jumper wires, connect terminals No. 2 and 3 on harness side of FTDP sensor connector to respective terminals on sensor side of FTDP sensor connector. Turn ignition on. Ensure fuel cap is removed. Check voltage between ground and FTDP sensor connector terminal No. 1 (component side). Voltage should be 2-3 volts. If voltage is not as specified, replace FTDP sensor, then go to step  22. If voltage is as specified, go to next step.
  6. Turn ignition off. Remove jumper wires and reconnect FTDP sensor connector. Measure voltage between ground and PCM connector D-109 terminal No. 92 (Blue/Yellow wire) by backprobing. See Figure. Voltage should be 2-3 volts. If voltage is as specified, go to next step. If voltage is not as specified, repair open in Blue/Yellow wire between FTDP sensor and PCM, then go to step  22.
  7. Check PCM connector D-109 for loose, damaged, or corroded terminals. If problem exists, repair connector, then go to step  22. If problem does not exist, replace PCM, then go to step  22.
  8. Measure voltage between ground and PCM connector D-108 terminal No. 46 (Green/Yellow wire) by backprobing. See Figure. Voltage should be 4.8-5.2 volts. If voltage is as specified, repair open in Green/Yellow wire or Green/Red wire between PCM and FTDP sensor, then go to step  22. If voltage is not as specified, go to next step.
  9. Turn ignition off. Disconnect PCM connector D-108. Check PCM connector D-108 for loose, damaged, or corroded terminals. If problem exists, repair connector, then go to step  22. If problem does not exist, go to next step.
  10. Check for continuity between ground and PCM connector D-108 terminal No. 46 (Green/Yellow wire). If continuity exists, repair short to ground in sensor power feed circuit (Green/Yellow wire) between PCM and Manifold Differential Pressure (MDP) sensor, Throttle Position (TP) sensor, Volume Airflow (VAF) sensor, or FTDP sensor, then go to step  22. See WIRING DIAGRAMS. If continuity does not exist, replace PCM, then go to step  22.
  11. Reconnect FTDP sensor connector. Turn ignition on. Measure voltage between ground and PCM connector D-108 terminal No. 57 (Black wire) by backprobing. See Figure. Voltage should be 0.5 volt or less. If voltage is as specified, repair Black wire between PCM and FTDP sensor, then go to step  22. If voltage is not as specified, go to next step.
  12. Turn ignition off. Check PCM connector D-108 for loose, damaged, or corroded terminals. If problem exists, repair connector, then go to step  22. If problem does not exist, replace PCM, then go to step  22.
  13. Turn ignition off. Push in flapper door on fuel filler neck to operate fuel overflow limiter valve. Fuel overflow limiter valve plunger should move toward top. Reinstall and tighten fuel cap 3 clicks. Remove fuel cap and check if fuel overflow limiter valve plunger was pushed back. Distance between tip of fuel overflow limiter valve plunger and top of fuel filler neck should be 1.1" (28 mm) or more. If fuel overflow limiter valve plunger does not return, replace fuel filler neck, install fuel cap and go to step  22. If fuel overflow limiter valve plunger is okay, install fuel cap and go to next step.
  14. Disconnect hoses "U" and "V" from ventilation solenoid. See Figure. Connect hand vacuum pump to ventilation solenoid port from which hose "U" was removed. Using hand vacuum pump, apply vacuum. Vacuum should leak. Turn ignition on. Using scan tool, perform actuator test No. 29 (ventilation solenoid) and turn on (close) ventilation solenoid. Using hand vacuum pump, apply vacuum. Vacuum should hold. If ventilation solenoid operates normally and holds vacuum when actuated, go to next step. If ventilation solenoid operates normally, but does not hold vacuum when actuated, replace ventilation solenoid, then go to step  22. If ventilation solenoid does not operate properly, diagnose ventilation solenoid problem. See DTC P0446: EVAPORATIVE EMISSION (EVAP) SYSTEM VENT CONTROL MALFUNCTION .
  15. Disconnect hose "E" from EVAP canister. See Figure. Using EVAP system pressure pump connected to fuel filler neck, pressurize system. Air should pass through end of hose "E". If air passes through hose "E", go to next step. If air does not pass through hose "E", go to step  19.
  16. Remove EVAP canister. Using hand vacuum pump, check hoses "U", "V", and "W" for clogging. See Figure. If clogging exists, replace appropriate hose, install EVAP canister, then go to step  22. If clogging does not exist, go to next step.
  17. Connect hand vacuum pump to EVAP canister port from which hose "E" was removed. Plug other 2 ports. Using hand vacuum pump, apply vacuum. Remove plug from each port in turn. When each plug is removed, vacuum should leak. If vacuum leaks as specified, go to next step. If vacuum does not leak as specified, replace EVAP canister, then go to step  22.
  18. Check air filter for clogging. See Figure. If clogging exists, replace air filter, then go to step  22. If clogging does not exist, go to step  22.
  19. Using hand vacuum pump, check hose "E" for clogging. If clogging exists, replace hose, then go to step  22. If clogging does not exist, go to next step.
  20. Remove fuel filler neck assembly. Using hand vacuum pump, check hoses "H" and "I" for clogging. See Figure. If clogging exists, replace appropriate hose, install fuel filler neck assembly, then go to step  22. If clogging does not exist, go to next step.
  21. Remove fuel tank. Using hand vacuum pump, check hoses "F" and "G" for clogging. See Figure and Figure. If clogging exists, replace appropriate hose, install fuel tank and fuel filler neck, then go to next step. If clogging does not exist, go to next step.
  22. Reconnect all connectors and install all removed components. Test drive vehicle following OBD-II drive cycle EVAP system leak monitor pattern. See EVAP SYSTEM LEAK MONITOR  under OBD-II DRIVE CYCLES under VERIFYING REPAIRS. Check for DTCs. If DTC P0450 is output, replace PCM. If DTC P0450 is not output, inspection is complete.
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