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P1456






P1456-FUEL TANK PRESSURE SENSOR CIRCUIT LOW

Special Tools:






For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
Ignition Key on. Battery voltage greater than 10.38V

- Set Condition:
The Powertrain Control Module (PCM) detects that the Fuel Tank Pressure Sensor (FTP) input voltage is below the minimum acceptable value. One Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

NOTE: Diagnose and repair any system voltage or sensor supply voltage DTCs before continuing with this test.

2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. (F856) 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Disconnect the FTP Sensor harness connector.
3. Ignition on, engine not running.
4. Measure the voltage on the (F856) 5-volt Supply circuit in the FTP Sensor harness connector.

Is the voltage between 4.5 to 5.2 Volts?

Yes

- Go To 3

No

- Go To 7

3. FTP SENSOR
1. With the scan tool, monitor the FTP Sensor voltage with the Sensor harness connector disconnected.

NOTE: The sensor voltage should be approximately 5.0 Volts (plus or minus.1 volt) with the connector disconnected.

Does the scan tool display the voltage as described above?

Yes

- Verify that there is good pin to terminal contact in the FTP Sensor and Powertrain Control Module connectors. Replace the FTP Sensor if no problems were found with the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. (N7) FTP SIGNAL CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the C4 PCM harness connector.
3. Measure the resistance between ground and the (N7) FTP Signal circuit in the FTP Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the (N7) FTP Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. (N7) FTP SIGNAL CIRCUIT SHORTED TO THE (K917) SENSOR GROUND CIRCUIT




1. Measure the resistance between the (N7) FTP Signal circuit and the (K917) Sensor ground circuit in the FTP Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the (K917) Sensor ground circuit and the (N7) FTP Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. EXCESSIVE RESISTANCE IN THE (N7) FTP SIGNAL CIRCUIT

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install the PCM Pinout Box (8815A) to perform diagnosis.





1. Measure the resistance of the (N7) FTP Signal circuit between the FTP Sensor harness connector and the appropriate terminal of the PCM Pinout Box 8815.

Is the resistance below 5.0 Ohms?

Yes

- Go To 9

No

- Repair the excessive resistance in the (N7) FTP Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

7. (F856) 5-VOLT SUPPLY CIRCUIT OPEN




1. Turn the ignition off.
2. Disconnect the C1 PCM harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the PCM Pinout Box (8815A) to perform diagnosis.

3. Measure the resistance of the (F856) 5-volt Supply circuit from the FTP Sensor harness connector to the appropriate terminal of the Pinout Box 8815.

Is the resistance below 5.0 Ohms?

Yes

- Go To 8

No

- Repair the open in the (F856) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

8. (F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (F856) 5-volt Supply circuit in the FTP Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the (F856) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 9

9. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the FTP Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the FTP Sensor and Powertrain Control Module connectors.
4. Search for any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

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