P0452

DTC P0452

CIRCUIT DESCRIPTION




The DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage diagnostic monitors the function of the FTP sensor circuit. The control module monitors the 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 control module detects the FTP sensor signal voltage above a calibrated value, this DTC will set.




The table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.

DTC DESCRIPTOR
This diagnostic supports the following DTC.
DTC P0452 Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage

CONDITIONS FOR RUNNING THE DTC
- DTC P0453 is not set.
- The ignition is ON.
- DTC P0452 runs once per drive cycle when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The FTP sensor voltage is more than 4.9 volts for more than 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.
- Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
- The FTP sensor parameter on the scan tool should read between 1.4 volts and 1.5 volts with the ignition ON, engine OFF and the fuel cap removed. This represents atmospheric pressure of 0 inches of vacuum.
- The FTP sensor 5-volt reference circuit is shared with the following sensors:
- The exhaust gas recirculation (EGR) sensor
- A/C Refrigerant Pressure Sensor
- A/T Input Shaft Speed (ISS) Sensor
- The accelerator pedal position (APP) sensor 2
- Inaccurate readings will occur if resistance measurements are taken on a FTP sensor. The FTP sensor contains an internal amplifier circuit that requires applied voltage to function properly
- To locate an intermittent problem, monitor the FTP sensor voltage with the ignition ON, engine OFF. Wiggling wires, while watching for change in the FTP sensor voltage, may help locate the area where fault may exist.
- For intermittent conditions, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-11:

Steps 12-14:

The number below refers to the step number on the diagnostic table.
2. If DTC P0651 set, the 5-volt reference circuit may be shorted to a voltage.
12. After replacing the PCM a new minimum throttle position and idle speed must also be established.