GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0452: Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage

DTC P0453: Fuel Tank Pressure (FTP) Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

5-Volt Reference

P0107, P0405, P0452, P0651, P2077

P0452

P0107, P0651, P2106, P2138

--

FTP Sensor Signal

P0452

P0452

P0446, P0453

--

Low Reference

--

P0446

--

--

Typical Scan Tool Data

FTP Sensor

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine operating in Closed Loop at idle.

Parameter Normal Range: 02 V-4.8 V

5-Volt Reference Voltage

0 V

0 V

0.7 V

FTP Sensor Signal

0 V

0 V

5 V

Low Reference

--

4.2 V

--

Circuit/System Description

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.

FTP Sensor Signal Voltage

Fuel Tank Pressure

High, Approximately 1.5 Volts or More

Negative Pressure/Vacuum

Low, Approximately 1.5 Volts or Less

Positive Pressure

Conditions for Running the DTC

    • The ignition is ON or the engine is operating.
    • The DTCs run continuously once the above condition is met.

Conditions for Setting the DTC

P0452

The ECM detects the FTP sensor voltage is less than 0.2 volt.

P0453

The ECM detects the FTP sensor voltage is more than 4.8 volts.

Action Taken When the DTC Sets

DTC P0452 and P0453 are Type B DTCs.

Conditions for Clearing the DTC

DTC P0452 and P0453 are Type B DTCs.

Diagnostic Aids

    • If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.
    • The scan tool 5 volt reference parameter should display between 4.8-5.2 volts.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification

  1. Ignition ON, observe the DTC information with a scan tool. Verify DTC P0651 is not set.
  2. If DTC P0651 is set, refer to DTC P0641 or P0651 .
  3. Observe the scan tool FTP Sensor voltage parameter. The FTP sensor voltage should be between 0.2-4.0 volts.
  4. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector of the FTP sensor.
  2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit and ground.
  3. If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

    Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.

  4. Ignition ON, load test for 4.8-5.2 volts between the 5-volt reference circuit and ground.
  5. If less than the specified range, test the 5-volt reference circuit for a short to ground or 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. Ignition ON, verify that the scan tool FTP Sensor voltage parameter is less than 4.8 volts
  7. If greater than the specified value, test the signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
  8. Install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit. Verify that the scan tool FTP Sensor voltage parameter is greater than 4.8 volts.
  9. 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.
  10. If all circuits/connections test normal, replace the FTP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Tank Pressure Sensor Replacement
    •  Control Module References for engine control module replacement, setup, and programming