P0450
CIRCUIT DESCRIPTIONThe Fuel Tank Pressure (FTP) sensor is mounted to the sending unit at the top of the fuel tank. The FTP sensor measures the pressure changes within the Evaporative Emissions (EVAP) system. The fuel tank pressure sensor has a 5-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 between 2-10 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 control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the 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. Intermittent Conditions
TEST DESCRIPTION
Steps 1-8:
Steps 9-15:
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 (MAF) sensor and Accelerator Pedal Position (APP) sensor 1. A short to ground or to voltage on the 5-volt reference circuit will set a DTC P0100 along with the DTC P0450. These circuit conditions are diagnosed in the table for DTC 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 DTC P0100.