P0453

Diagnostic Chart:

Schematics:

CIRCUIT DESCRIPTION
The Fuel Tank Pressure (FTP) sensor responds to changes in the Fuel Tank Pressure or vacuum. This information is used in order to detect vacuum decay or an excessive vacuum during the EVAP diagnostic routing. The FTP sensor signal voltage to the VCM varies from a minimum of about 0.1 volts with pressure in the fuel tank to more than 4.0 volts with a high vacuum in the fuel tank.

The FTP sensor display on the scan tool has an auto-zero feature which occurs at each ignition cycle and is corrected according to the barometric pressure. Because of this, the FTP sensor display may not accurately reflect the actual output of the sensor or the conditions within the fuel tank. The FTP sensor diagnosis table is intended to isolate and diagnose the electrical problems in the sensor wiring or in the sensor.

CONDITIONS FOR RUNNING THE DTC
The ignition switch is in the RUN position.

CONDITIONS FOR SETTING THE DTC
The FTP sensor voltage is more than 4.98 volts for more than 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
The VCM turns ON the Malfunction Indicator Lamp (MIL) after 2 consecutive driving cycles with the fault active.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
^ A scan tool can clear the DTCs.

DIAGNOSTIC AIDS
1. Inspect the control module harness connectors for the following conditions:
^ Backed-out terminals
^ Improper mating
^ Broken locks
^ Improperly formed or damaged terminals
^ Faulty terminal-to-wire connection
2. Inspect the wiring harness for damage. If the harness appears to be OK, observe the FTP sensor display on the scan tool while moving the connectors and the wiring harnesses related to the sensor. A change in the display will indicate the location of the fault. Refer to Wiring Repairs in Diagrams.

TEST DESCRIPTION
The numbers below refer to the Step numbers on the diagnostic table.
2. If the FTP sensor value is less than -16.50 inches H2O, an FTP sensor circuit problem or an internally shorted FTP sensor may be present. Note that -17.32 inches H2O is less than -16.50 inches H2O.
3. It the FTP sensor value is more than 7.4 inches H2O, the fault is the FTP sensor or the reference voltage is more than 5.00 volts. With good circuits, a disconnected FTP sensor should indicate 7.4 inches H2O.
7. A high voltage reading on the 5 volt reference circuit could be caused by a short to voltage on another 5 volt reference circuit, some 5 volt reference circuits are shared inside and outside the VCM. A defective linear EGR valve may bleed battery voltage onto the 5 volt reference circuit.