Circuit Description
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The control module monitors the Fuel Tank Pressure (FTP) sensor signal in order to detect vacuum decay and excess vacuum during the Evaporative Emission (EVAP) diagnostic test. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. If the FTP sensor signal voltage is not within a calibrated value range during a cold engine start, this DTC sets.
The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum. See FTP SENSOR SIGNAL VOLTAGE-TO-FUEL TANK PRESSURE RELATIONSHIP table.
FTP SENSOR SIGNAL VOLTAGE-TO-FUEL TANK PRESSURE RELATIONSHIP
| FTP Sensor Signal Voltage | Fuel Tank Pressure |
|---|---|
| High - About 1.5 Volts Or Greater | Negative Pressure/Vacuum |
| Low - About 1.5 Volts Or Less | Positive Pressure |