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 P0450: Fuel Tank Pressure (FTP) Sensor CircuitDTC 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 | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
5-Volt Reference | * | -- | P0120, P0122, P0450, P0453 | ** | -- |
FTP Sensor Signal | P0452 | P0451 | P0453 | P0453** | P0451 |
Low Reference | -- | P0451 | P0110, P0113, P0115, P0118, P0120, P0123, P0220, P0223, P0450, P0453 | -- | -- |
*Engine cranks but won't start **Internal PCM or FTP sensor damage may occur if the circuit is shorted to B+ | |||||
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: The engine coolant temperature is greater than 70°C (158°F) and the ignition is ON with the engine is OFF. Parameter Normal Range: FTP Sensor 3.5-3.8 volts | |||
5-Volt Reference | * | 5.0 volts | ** |
FTP Sensor 1 Signal | 0.1 volts | 5.0 volts | 5.0 volts |
Low Reference | -- | 5.0 volts | -- |
*No scan tool communication with control module **Internal PCM or FTP sensor damage may occur if the circuit is shorted to B+ | |||
Circuit/System Description
The FTP sensor is used to detect any unexpected pressure in the EVAP system. The PCM supplies a 5-volt reference, an electrical ground, and a signal return circuit that has a 5-volt bias. The FTP sensor contains a silicon based chip that changes electrical resistance when pressure is applied. The sensor converts the positive or the negative pressure into an electrical signal and sends the signal to the PCM.
Fuel Tank Vapor Space | FTP mmHg | FTP Signal Voltage |
|---|---|---|
Pressure | Positive Value | High |
No Pressure | Near Zero | 3.0-3.6V |
Vacuum | Negative Value | Low |
Conditions for Running the DTC
| • | The engine is running. |
| • | The intake air temperature is between 4-35°C (40-95°F). |
| • | The DTC P0450, P0452 and P0453 run once per ignition cycle when the above conditions are met. |
Conditions for Setting the DTC
P0450
| • | The FTP sensor signal indicates a pressure less than -30 mm Hg (-16.32 in H2O) for 7 seconds. |
| OR |
| • | The FTP sensor signal indicates a pressure greater than 15 mm Hg (8 in H2O) for 7 seconds. |
P0452
The FTP sensor signal indicates a pressure less than -30 mm Hg (-16.32 in H2O) for 7 seconds.
P0453
The FTP sensor signal indicates a pressure greater than 15 mm Hg (8 in H2O) for 7 seconds.
Action Taken When the DTC Sets
DTC P0450, P0452, and P453 are Type A DTCs.
Conditions for Clearing the DTC
DTC P0450, P0452, and P453 are Type A DTCs.
Diagnostic Aids
| • | If a shared 5-volt reference circuit is shorted to ground the engine will not start and the PCM will not communicate with the scan tool. |
| • | The EVAP system diagnostic can be monitored on the scan tool under the I/M System Information selection. When the EVAP test displays a YES status, indicating that the system diagnostic is completed, check for DTC P0450, P0452, or P0453 in the Last Test Failed screen of the scan tool. If there is no FTP sensor DTC displayed the EVAP system diagnostic has run and passed, indicating that no malfunction was present this time. DTCs MUST be cleared in order to view the Current Status of the system diagnostics being performed. Do not forget that the I/M System Information tests only indicate that the test has run, not if the test passed or failed. The Last Test Failed screen must be checked for related DTCs in order to determine the outcome of the diagnostic test involved. |
Reference Information
Schematic Reference
Connector End View Reference
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
Circuit/System Verification
- Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0115, P0117, P0118, P0120, P0122, or P0123 are not set.
- Ignition OFF, remove the fuel tank filler cap.
- Ignition ON, observe that the FTP sensor scan tool parameter is between 3.5-3.8 volts.
- 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 you observed from the Freeze Frame/Failure Records data.
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. |
Important: The FTP sensor reading will vary slightly with atmospheric pressure. The values indicated are for pressures at sea level.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the EVAP canister assembly.
- Ignition OFF, test for 5 ohms or less of resistance between the low reference circuit terminal 4 and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.
- Observe that the FTP sensor scan tool parameter is 5.0 volts.
- Install a 3A fused jumper wire between ground and the FTP sensor signal circuit terminal 3. Verify the FTP sensor scan tool parameter is less than 0.1 volt.
- If all circuits test normal, replace the FTP sensor located in the EVAP vacuum leak pump assembly.
| ⇒ | If greater than the specified range, test the low reference circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the PCM. |
| ⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the PCM. |
| ⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the PCM. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the PCM. |
| ⇒ | If greater than the specified range, test the appropriate signal circuit for a short to voltage. If the circuit tests normal, replace the PCM. |
| ⇒ | If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the PCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for control module replacement, setup, and programming |
