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Home >> Mitsubishi >> 2000 >> Mirage Sedan LS L4-1834cc 1.8L SOHC MFI >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0450

P0450

SYSTEM DIAGRAM:




FUEL TANK DIFFERENTIAL PRESSURE SENSOR CIRCUIT:




CONNECTORS:






CIRCUIT OPERATION
- A 5-volt voltage is supplied to the power terminal of the fuel tank differential pressure sensor (terminal 3) from the ECM (terminal 81). The ground terminal (terminal 2) is grounded with the ECM (terminal 92).
- A voltage proportional to the pressure in the fuel tank is sent from the output terminal of the fuel tank differential pressure sensor (terminal 1) to the ECM (terminal 61).

TECHNICAL DESCRIPTION
- To judge if the fuel tank differential pressure sensor is defective, the ECM monitors the fuel tank differential pressure sensor output voltage.
- There are three different sets (A, B, C) of test conditions and the judgment criteria. Based on these lest conditions and judgment criteria, the ECM judges if the fuel tank differential pressure sensor output voltage is normal.

NOTE: In rare cases, this DTC may be also set under some fuel and driving conditions regardless of the fuel pressure sensor output voltage when the fuel system is clogged.

DTC SET CONDITIONS

Test Conditions A:
Fuel tank differential pressure sensor output voltage is less than the upper limit of the predetermined value
- Intake air temperature is higher than 5 °C [41 °F].
- Engine speed is 1,600 r/min or more.
- Volumetric efficiency is between 20 and 80 percent.
- Vehicle speed is 30 km/h (18.7 mph) or more.
- Evaporative emission purge solenoid is driven at a 100 percent duty when the intake air temperature is between 5 and 45 °C (41 - 113 °F).

Judgment Criteria A
- The sensor output voltage remains 4.0 V or more for 10 seconds or more.

Test Conditions B:
Fuel tank differential pressure sensor output voltage is more than the lower limit of the predetermined value
- Intake air temperature is higher than 5 °C(41 °F).
- Engine speed is 1,600 r/min or more.
- Intake pipe pressure is between 27 kPa and 93 kPa (3.9 to 13.5 psi).
- Vehicle speed is 30 km/h (18.7 mph) or more.
- Evaporative emission purge solenoid is not driven when the intake air temperature is 5 °C (41 °F) or more.

Judgment Criteria B
- The sensor output voltage remains less than 1.0 Volt for 10 seconds or more.

Test Conditions C:
Electrical noise
- Idle switch: ON.
- Vehicle speed is 1.5 km/h (0.93 mph) or less.

Judgment Criteria C
- The ECM looks for rapid voltage changes (electrical noise) equal to 20 or more spikes of 0.2 volts or more in 25 millisecond averaged blocks.
- The ECM must see this activity during 8 consecutive idling periods from engine starting.

NOTE:. Rapid voltage occurs due to fuel sloshing during refuelling. However, when the ECM sees the activity mentioned above 8 consecutive times, it judges that an electrical noise is present.

The ECM determines that the engine is not idling if all of the following conditions are met
- Engine speed is higher than 2,500 r/min.
- Vehicle speed is 15 km/h (9.3 mph) or more.
- Volumetric efficiency is 55 percent or more.

TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Fuel tank differential pressure sensor failed.
- Open or shorted fuel tank differential pressure sensor circuit, or loose connector.
- ECM failed.
- Blockage of evaporative emission system (causing high pressure)

OVERVIEW OF TROUBLESHOOTING
- The DTC P0450 can be set if either of the following conditions occur:
1. Faulty fuel differential pressure sensor, related circuit, or ECM.
2. Faulty fuel filler neck evaporative emission ventilation solenoid or blocked vapor line.

- If the fuel filler neck evaporative emission ventilation solenoid is faulty and stays closed or the vapor line is blocked, the pressure inside the fuel tank is increased as the evaporative fuel is not purged especially at hot ambient temperatures. Once the pressure inside the fuel tank reaches 5 kPa (0.73 psi), the sensor output voltage also reaches 4.0 volts. This will set the DTC P0450.
- To check a system blockage, do a performance test which uses a mechanical vacuum gauge and the scan tool MB991502 set on the fuel tank differential pressure sensor (TANK PRS SNSR73). The mechanical gauge reading is used to verify the scan tool MB991502 reading. A comparison of the mechanical gauge to the scan tool MB991502 determines the problem in the system.




DIAGNOSIS
Required Special Tools:
MB991502: Scan Tool (MUT-II)
MB991658: Test Harness Set

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.




STEP 1. Using scan tool MB991502, check data list item 73: Fuel Tank Differential Pressure Sensor.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Remove the fuel cap.
4. Disconnect the evaporative emission ventilation solenoid side of hose D and plug.
5. Set scan tool MB991502 to the data reading mode for item 73, Fuel Tank Differential Pressure Sensor.
- The fuel tank pressures should be -1.5 to 1.5 kPa.

6. Connect an evaporative emission system pressure pump to the fuel filler neck, and apply pressure.
- The scan tool reading should increase.

If within specifications, go to Step 20.

If not within specifications, go to Step 2.




STEP 2. Check the output circuit voltage at intermediate connector E-22.
1. Remove the rear seat cushion. (Refer to Rear Seat.)
2. Remove the quarter trim <2-door models> or scuff plate <4-door models>.
3. Full up the carpet.
4. Do not disconnect intermediate connector E-22.
5. Turn the ignition switch to "ON" position.
6. Remove the fuel cap.
7. Measure the voltage between terminal 1 and ground by backprobing.
- Voltage should be between 2.0 and 3.0 volts.

8. Turn the ignition switch "LOCK" (OFF) position.

If within specifications, go to Step 10.

If not within specifications, go to Step 3.




STEP 3. Check the 5-volt supply circuit voltage at intermediate connector E-22.
1. Do not disconnect intermediate connector E-22.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 2 and ground by backprobing.
- Voltage should be between 4.8 and 5.2 volts.

4. Turn the ignition switch to "LOCK" (OFF) position.

If within specifications, go to Step 4.

If not within specifications, go to Step 11.




STEP 4. Check the ground circuit voltage at intermediate connector E-22.
1. Do not disconnect intermediate connector E-22.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 3 and ground by backprobing.
- Voltage should be 0.5 volts or less.

4. Turn the ignition switch to "LOCK" (OFF) position.

If 0.5 volts or less, go to Step 5.

If more than 0.5 volts, go to Step 15.




STEP 5. Check the output circuit voltage at fuel tank differential pressure connector E-23.
1. Remove the muffler.
2. Separate the fuel feed line, return line and evaporator purge line.
3. Loosen the left side of the fuel tank installation band, disconnect the right side, and tilt the fuel tank.
4. Do not disconnect fuel tank differential pressure sensor connector E-23.
5. Turn the ignition switch to "ON" position.
6. Remove the fuel cap.
7. Measure the voltage between terminal 1 and ground by backprobing.
- Voltage should be between 2.0 and 3.0 volts.

8. Turn the ignition switch to "LOCK" (OFF) position.

If within specifications, go to Step 17.

If not within specifications, go to Step 6.




STEP 6. Check the 5-volt supply circuit voltage at fuel tank differential pressure sensor connector E-23.
1. Do not disconnect fuel tank differential pressure sensor connector E-23.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 3 and ground by backprobing.
- Voltage should be between 4.8 and 5.2 volts.

4. Turn the ignition switch to "LOCK" (OFF) position.

If within specifications, go to Step 7.

If not within specifications, go to Step 17.




STEP 7. Check the ground circuit voltage at fuel tank differential pressure sensor connector E-23.
1. Do not disconnect fuel tank differential pressure sensor connector E-23.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 2 and ground by backprobing.
- Voltage should be 0.5 volts or less.

4. Turn the ignition switch to "LOCK" (OFF) position.

If 0.5 volts or less, go to Step 8.

If more than 0.5 volts, go to Step 17.




STEP 8. Check fuel tank differential pressure sensor connector E-23 for damage.

If fuel tank differential pressure sensor connector E-23 is in good condition, go to Step 9.

If fuel tank differential pressure sensor connector E-23 is damaged, repair or replace it.

Refer to Harness Connector Inspection. Then go to Step 30.




STEP 9. Check the output voltage at fuel tank differential pressure sensor connector E-23.
1. Disconnect the fuel tank differential pressure sensor connector E-23.
2. Use special tool (MB991658) to connect terminals 2 and 3 of the harness side connector to those of the sensor side connector, respectively.
3. Turn the ignition switch to "ON" position.
4. Remove the fuel cap.
5. Measure the voltage between sensor side connector terminal 1 and ground.
- Voltage should be between 2.0 and 3.0 volts.

6. Turn the ignition switch 10 "LOCK" (OFF) position. If within specifications, check connectors E-22, B-36, B-38 and repair or replace as required.

Refer to Harness Connector Inspection. If connectors E-22, B-36, B-38 are in good condition, check the harness between fuel tank pressure sensor connector E-23 and ECM connector B-38 for short circuit to ground, and then repair if necessary. Then go to Step 30.

If not within specifications, replace the fuel tank differential pressure sensor. Then go to Step 30.




STEP 10. Check the output circuit voltage at ECM connector B-38.
1. Do not disconnect the ECM connector B-38.
2. Turn the ignition switch to "ON" position.
3. Remove the fuel cap.
4. Measure the voltage between terminal 61 and ground by backprobing.
- Voltage should be between 2.0 and 3.0 volts.

5. Turn the ignition switch to "LOCK" (OFF) position. If within specifications, go to Step 18.

If not within specifications, check connectors E-22, B-36, B-38 and repair or replace as required.

Refer to Harness Connector Inspection. If connectors E-22, B-36, B-38 are in good condition, check the harness between intermediate connector E-22 and ECM connector B-38 for open circuit or damage. Then repair if necessary. Then go to Step 30.




STEP 11. Check the 5-volt supply circuit voltage at ECM connector B-37.
1. Do not disconnect ECM connector B-37.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 81 and ground by backprobing.
- Voltage should be between 4.8 and 5.2 volts.

4. Turn the ignition switch to "LOCK" (OFF) position.

If within specifications, check connectors E-22, B-36, B-37, and repair or replace as required.

Refer to Harness Connector Inspection.

If connectors E-22, B-36, B-37 are in good condition, check the harness between intermediate connector E-22 and ECM connector B-37 for open circuit or damage. Then repair if necessary. Then go to Step 30.

If not within specifications, go to Step 12.




STEP 12. Check ECM connector B-37 for damage.
If connector B-37 is in good condition, go to Step 13.

If connector B-37 is damaged, repair or replace it.

Refer to Harness Connector Inspection. Then go to Step 30.




STEP 13. Check the sensor power supply line for short circuit to ground at ECM connector B-37.
1. Disconnect ECM connector B-37 and measure at the harness side.
2. Check for the continuity between terminal 81 and ground.
- There should be 2 Ohms or more.

If 2 Ohms or more, replace ECM. Then go to Step 30.

If less than 2 Ohms, go to Step 14.

STEP 14. Check the sensor power supply lines.
Check all the sensor power supply lines, which flow through the harness ECM connector (terminal 81) and then repair if necessary. (Refer to Circuit Diagrams). Then go to Step 30.




STEP 15. Check the ground circuit voltage at ECM connector B-37.
1. Do not disconnect ECM connector B-37.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 92 and ground by backprobing.
- Voltage should be 0.5 volts or less.

4. Turn the ignition switch to "LOCK" (OFF) position. If 0.5 volts or less, check connectors E-22, B-36, B-37 and repair or replace as required.

Refer to Harness Connector Inspection.

If connectors E-22, B-36, B-37 are in good condition, check the harness between intermediate connector E-22 and ECM connector B-37 for open circuit or damage, and then repair if necessary. Then go to Step 30.

If more than 0.5 volts, go to Step 16.




STEP 16. Check ECM connector B-37 for damage.
If connector B-37 is in good condition, replace the ECM.
Then go to Step 30.

If connector B-37 is damaged, repair or replace it.

Refer to Harness Connector Inspection. Then go to Step 30.







STEP 17. Check the harness between fuel tank differential pressure sensor connector D-18 and intermediate connector E-22 for open circuit or damage.
If the harness between fuel tank differential pressure sensor connector E-23 and intermediate connector E-22 is not damaged, check connectors E-23, E-22 and repair or replace as required.

Refer to Harness connector Inspection. Then go to Step 30.

If the harness between fuel tank differential pressure sensor connector E-23 and intermediate connector E-22 is damaged, repair it.
Then go to Step 30.




STEP 18. Check ECM connector B-38 for damage.
If connector B-38 is in good condition, go to Step 19.

If connector B-38 is damaged, repair or replace it.

Refer to Harness Connector Inspection. Then go to step 30.






CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.




STEP 19. Using scan tool MB991502, check data list item 73: Fuel Tank Differential Pressure Sensor.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Remove the fuel cap.
4. Disconnect the evaporative emission ventilation solenoid side of hose D and plug.
5. Set scan tool MB991502 to the data reading mode for item 73, Fuel Tank Differential Pressure Sensor.
- The fuel tank pressure should be -1.5 to 1.5 kPa.

6. Connect an evaporative emission system pressure pump to the fuel filler neck, and apply pressure.
- The scan tool reading should increase.

If within specifications, go to Step 30.

If not within specifications, replace the ECM. Then go to Step 30.




STEP 20. Check the fuel overflow limiter valve plunger and flapper door operation.

NOTE: The fuel overflow limiter valve plunger opens and closes in sequence with the flapper door and fuel overflow limiter valve plunger.

When the fuel gun is inserted in the fuel filler neck and the flapper door is opened, the fuel overflow limiter valve plunger will close. (The fuel overflow limiter valve plunger will move to the top of the neck.)

When the fuel cap is closed, the fuel cap pushes the fuel overflow limiter valve plunger and the fuel overflow limiter valve plunger opens.

If the flapper door or fuel overflow limiter valve plunger does not operate correctly, the fuel overflow limiter valve plunger will remain closed even if the fuel cap is closed (same state as when the evaporator line is clogged).

This can cause DTC P0450 to occur.

1. Remove the fuel cap.




2. Push the flapper with an ornament remover, etc., to activate the valve.

NOTE: The fuel overflow limiter valve plunger moves upward when the flapper is pushed.

3. Tighten the fuel cap until three clicks are heard.




4. Remove the fuel cap again, and with the fuel overflow limiter valve plunger pushed in, measure the projection amount.
5. Confirm that the distance from the end of the fuel tank filler neck to the end of the fuel overflow limiter valve plunger is 28 mm (1.1 inches) or more.

If the fuel overflow limiter valve plunger does not return completely [when less than 28 mm (1.1 inches)], replace the fuel tank filler neck, completely tighten the fuel cap and go to Step 30.

If the fuel overflow limiter valve plunger has completely returned [when 28 mm (1.1 inches) or more], completely tighten the fuel cap and go to Step 21.

STEP 21. Check for clogging in the evaporator line from hose H to J and from K to N and O, R.
1. Install the EVAP pressure pump outlet hose to the fuel tank filler neck as described in the pump manufacturer's instructions.




2. On the EVAP pressure pump, set the pressure/hold valve to OPEN, and set the vent valve to CLOSED. Turn the pump timer to ON. You can reset the timer as required. These settings are listed under "Leak Test" in the pump instructions.)




3. Air should pass through the air filter.

If the air passes, go to Step 28.

If the air does not pass, go to Step 22.

STEP 22. Check for clogging air filter.
Check the air filter for clogging.

If the air filter is clogged, replace the air filter. Then go to Step 30.

If the air filter is not clogged, go to Step 23.




STEP 23. Check the vent valve unit for clogging.
Check the vent valve unit for clogging.

If the vent valve unit is clogged, replace the vent valve unit. Then go to Step 30.

If the vent valve unit is not clogged, go to Step 24.




STEP 24. Check for clogging in the evaporator lines I, S and hose T.
The clogging test with a hand vacuum pump on each hose from hose I, S and hose T

If the clogging section is pinpointed, replace that hose, and go to Step 30.

If the location of the leak cannot be pinpointed, go to Step 25.




STEP 25. Check for clogging in the evaporator line hose H and hose J.
1. Remove the evaporative emission canister assembly. (Refer to Emission Control System)
2. The leakage test with a hand vacuum pump on each hose H and hose

If the location of the leak or clog is pinpointed, replace that hose, install the evaporative emission canister assembly. Then go to Step 30.

If the location of the leak or clog cannot be pinpointed, go to Step 26.

STEP 26. Check the evaporative emission ventilation solenoid using the scan tool MB991502. (Actuator test item 29)




1. Turn the ignition switch to "ON" position, and disconnect the hose J from the evaporative emission ventilation solenoid side.




2. Connect the hand vacuum pump to the nipple of the evaporative emission ventilation solenoid from which the hoses have been disconnected.
3. Drive the evaporative emission ventilation solenoid with the scan tool MB991502 actuator test, and confirm that the vacuum does not fluctuate when the vacuum is applied with the hand vacuum pump.

If the evaporative emission ventilation solenoid operates correctly and the applied vacuum does not fluctuate, go to Step 27.

If the evaporative emission ventilation solenoid operates correctly, but the vacuum is not maintained, replace the evaporative emission ventilation solenoid, and then go to Step 30.

If the evaporative emission ventilation solenoid does not operate, refer to the evaporative emission ventilation solenoid trouble code DTC P0446.




STEP 27. Check for clogging in the evaporative emission canister.
1. Connect a hand vacuum pump to the vent nipple of the evaporative emission canister.
2. Plug the other two nipples or loop a hose between the other nipples.
3. Apply vacuum. When each nipple is unplugged, the vacuum should fluctuate.

If the applied vacuum fluctuates, and install the evaporative emission canister assembly. Then go to Step 30.

If the vacuum does not fluctuate, replace the evaporative emission canister assembly, install the evaporative emission canister assembly. Then go to Step 30.




STEP 28. Check for clogging in the evaporator lines hoses O and hose R.

The clogging lest with a hand vacuum pump on each hose from hose Q and hose R.

If the clogging section is pinpointed, replace that hose, and go to Step 30.

If the clogging section cannot be pinpointed, go to Step 29.




STEP 29. Check for clogging in the evaporator line from hose K.
1. Remove the fuel tank.
2. Carry out the clogging test with a hand vacuum pump on each hose from hose K.

If the location of the leak or clog is pinpointed, replace that hose, reinstall the fuel tank, and go to Step 30.

If the location of the leak or clog cannot be pinpointed, and install the fuel tank. Then go to Step 30.

STEP 30. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 1 - Evaporative Emission Control system Leak Monitor.
2. Read the diagnostic trouble code, and confirm that diagnostic trouble code P0450 does not reset.
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