Note. For circuit reference, see ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. For component locations, see COMPONENT LOCATIONS . For connector identification, see CONNECTOR IDENTIFICATION .
Circuit Description
The DTC P0450 Fuel Tank Pressure (FTP) Sensor Circuit diagnostic monitors FTP sensor voltage. Evaporative Emission (EVAP) control system prevents emission of fuel vapors. Fuel vapor generated in fuel tank while driving or idling enters EVAP canister where a charcoal element absorbs and stores fuel vapor. When certain engine operating conditions are met, Powertrain Control Module (PCM) purges EVAP canister of stored vapors by turning ON EVAP canister purge valve.
Emissions laws require that PCM detect any leakage within EVAP system. PCM monitors EVAP system for leaks by controlling and observing vapor pressures in EVAP system. FTP sensor is used to detect any unexpected pressure in EVAP system. PCM supplies a 5-volt reference and an electrical ground to FTP sensor. FTP sensor contains a silicone based chip that changes electrical resistance when pressure is applied. The sensor converts positive or negative pressure into an electrical signal and sends the signal to the PCM. See FUEL TANK PRESSURE SENSOR OPERATION table.
| Fuel Tank Vapor Space | FTP - In. Hg | FTP Signal Voltage |
|---|---|---|
| Pressure | Positive Value | High |
| No Pressure | Near Zero | 3.0-3.6 Volts |
| Vacuum | Negative Value | Low |
FUEL TANK PRESSURE SENSOR OPERATION