P0450

Schematic:

CIRCUIT DESCRIPTION
The Fuel Tank Pressure (FTP) sensor is mounted to the sending unit at the' top of the fuel tank. The fuel tank pressure sensor measures the pressure changes within the Evaporative Emissions (EVAP) system. The fuel tank pressure sensor has a 5.0 volt reference circuit, a ground circuit, and a signal circuit.

The fuel tank pressure sensor contains a diaphragm that changes resistance as the pressure in the EVAP system changes. When the EVAP system pressure is low or in a vacuum during purge, the sensor output voltage is low. When the system pressure is high, the sensor output voltage is high.

CONDITIONS FOR RUNNING THE DTC

Part 1:
Test continuously.

Part 2:
^ The engine is at idle.
^ The Engine Coolant Temperature (ECT) at start is less than 33°C (91°F).
^ The engine is running between2 to 10 seconds.

CONDITIONS FOR SETTING THE DTC

Part 1:
^ The tank pressure is more than 22.50 mm Hg (12.05 in H2O).
^ The above condition is met for at least 5 seconds.

OR

^ The tank vacuum is more than -22.03 mm Hg (-11.80 in H2O).
^ The above condition is met for at least 5 seconds.

Part 2:
^ The tank pressure is more than 7 mm Hg (3.76 in H2O).
^ The above condition is met for at least 3 seconds.

ACTION TAKEN WHEN THE DTC SETS
The ECM illuminates the Malfunction Indicator Lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes.
^ A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.
^ The scan tool clears the MIL/DTC.

DIAGNOSTIC AIDS
^ Use the J 35616-A connector test adapter kit for any test that requires probing the ECM harness connector or a component harness connector.
^ Inspect for a condition that may cause excess pressure in the fuel tank such as a restricted vent or sticking EVAP vent solenoid.
^ Refer to Intermittent Conditions if the condition is not present at this time.

TEST DESCRIPTION

Steps 1 - 7:

Steps 8 - 15:

Steps 16 - 25:

The numbers below refer to the step numbers on the diagnostic table.
2. The FTP sensor shares the 5 volt reference with the mass air flow sensor and accelerator pedal position sensor 1. A short to ground or to voltage on the 5 volt reference circuit will set a P0100 along with the P0450. These circuit conditions are diagnosed in the table for P0100.
8. The FTP sensor signal circuit is pulled up to 5 volts in the ECM.
11. The ECM provides the reference ground for the FTP sensor. A small amount of voltage will appear on this circuit when the ECM is operational. The measured resistance of the circuit will increase when the ECM is operational. This is considered normal.
16. Disconnecting the ECM C2 connector will prevent the engine controls power relay from operating. When testing for a short to voltage on an ECM circuit, this relay should be energized.
17. The only circuit fault that should be present at this point is an open circuit. A short to ground or voltage on the 5 volt reference circuit should set a P0100.