The evaporative emission (EVAP) system is used to store fuel vapors in order to reduce the amount of fuel vapors into the atmosphere. The fuel tank pressure (FTP) sensor is only used for EVAP system diagnostics. The FTP sensor is a transducer that varies resistance according to changes in the fuel tank pressure. The engine control module (ECM) monitors the FTP sensor signal in order to detect vacuum decay and excess vacuum during the EVAP system diagnostic test. The ECM supplies a 5-volt reference and a low reference circuit to the FTP sensor.

The engine is operating.

P0452

The ECM detects the FTP sensor signal voltage is less than 0.13 volts for 4 seconds or for a cumulative of 50 seconds.

P0453

The ECM detects the FTP sensor signal voltage is greater than 4.6 volts for 4 seconds or for a cumulative of 50 seconds.

DTC P0452 and P0453 are Type B DTCs.

DTC P0452 and P0453 are Type B DTCs.

The following table illustrates the ECM connector locations:

If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Evaporative Emission Control System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool FTP Sensor voltage parameter. The FTP sensor voltage parameter should be between 0.1-4 volts.
2. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

1. Ignition OFF, remove the fuse that supplies B+ to terminal X2-36 of the ECM.
2. Disconnect the C405 harness connector at the rear of the fuel tank.
3. Test for less than 5 ohms of resistance between the low reference circuit terminal H and ground, at the ECM side of the connector.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

4. Install the fuse that supplies B+ to terminal X2-36 of the ECM.
5. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal F and ground, at the ECM side of connector C405.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground, or an open/high resistance. If the circuit/connections test normal, replace the ECM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

6. Verify the scan tool FTP Sensor parameter is less than 4.8 volts

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.

7. At the ECM side of C405, install a 3A fused jumper wire between the signal circuit terminal G and the 5-volt reference circuit terminal F. Verify the scan tool FTP Sensor parameter is greater than 4.8 volts.

⇒	If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.

8. Remove the fuel tank. Refer to Fuel Tank Replacement .
9. Disconnect the harness connector at the FTP sensor.
10. Inspect the FTP sensor circuits in the fuel tank harness, between the FTP sensor connector and C405 for the following conditions:

•	Damaged wiring or terminals

•	Open circuits

•	Short to ground

•	Wire to wire short

⇒	If a condition is located, repair as necessary.

11. If all circuits/connections test normal, replace the FTP sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.