P0450

Diagram Chart:

Electrical:

CIRCUIT DESCRIPTION

The Fuel Tank Pressure 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 EVAP system. The Fuel Tank Pressure sensor has a 5.0 volt reference, a ground and a signal circuit.

The Fuel Tank Pressure sensor contains a diaphragm which changes the resistance based on the pressure. When the EVAP system pressure is low (during the purge) the sensor output voltage is low. When the system pressure is high, the sensor output voltage is high.

When the ECM senses the Fuel Tank Pressure sensor signal voltage outside the normal operating range of the sensor, this DTC will set.

CONDITIONS FOR RUNNING THE DTC

Part 1:

Test continuously.

Part 2:

^ The engine is at idle.

^ The ECT is at start less than 33°C (91°F).

^ The engine is running between 2 to 10 seconds.

CONDITIONS FOR SETTING THE DTC

Part 1:

^ The tank pressure is greater than 27.6 kPa (1.1 in H2O).

^ The above condition met for at least 5 seconds

OR

^ The tank pressure is less than -28 kPa (1.1 in H2O).

^ The above condition met for at least 5 seconds.

Part 2:

^ The tank pressure is greater than 10 kPa (0.4 in H2O).

^ The above condition 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 does not fail.

^ A History DTC clears after forty consecutive warm-up cycles if no failures report by this diagnostic or any other emission related diagnostic.

^ The ECM battery voltage is interrupted.

^ The scan tool clears the MIL/DTC.

DIAGNOSTIC AIDS

Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check for the following conditions:

^ Poor connections at the ECM or at the component. Inspect the harness connectors for any backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Overall Vehicle Information / Diagrams / Diagnostic Aids for Checking Terminal Contact procedure.

^ Misrouted harness. Inspect the harness in order to ensure that the harness is not routed too close to any high voltage wires such as spark plug leads, or too close to any high current devices such as the alternator, the motors, the solenoids, etc.

^ Damaged harness. Inspect the wiring harness for any damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault.

If the sensor signal is only affected when the harness is moved at a component, and there is no problem with the harness or connections, the component may be damaged.

Refer to Symptoms / Intermittents. Testing and Inspection

TEST DESCRIPTION

The number(s) below refer to the step number(s) on the Diagnostic Table.

5. Using the Freeze Frame data may aid in locating an intermittent condition. If the DTC cannot be duplicated, review the information in the Freeze Frame. Try to operate the vehicle within the same freeze frame conditions (the RPM, the MAF, the vehicle speed, the temperature, etc.) that were noted. This process may help in order to recreate the malfunction.