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P1446






P1446-FUEL TANK CONTROL SYSTEM PERFORMANCE - HEV





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

Theory of Operation

The intent of the Fuel Tank Control System is to check for proper operation of the Fuel Tank Isolation Valve (FTIV) and the Fuel Tank Pressure Sensor (FTPS). The FTPS is used as feedback control for the FTIV. When pressure or vacuum exceeds preset limits for the tank, purge is shut off and the FTIV is opened to relieve pressure/vacuum from the tank. Once pressure/vacuum has been relieved and back within normal operating values, the FTIV is closed and purge is resumed. The FTPS confirms that the FTIV has been engaged and the fuel tank is isolated. The Fuel Tank Control System (FTCS) rationality indicates that the feedback loop is not working, in other words the FTPS does not indicate the tank is isolated.

- When Monitored:
Ambient Temp -6.7° C (20° F) Fuel level between 80% and 12% system voltage greater than 10.4V

- Set Condition:
This DTC will set if: Rationality shows that FTIV is stuck or open, the FTPS signal is valid but stuck or the FTPS signal is erratic.





WARNING: On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury

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.

NOTE: It is possible that other evaporative emission DTCs to set this DTC. Diagnose and repair any evaporative emission DTCs before continuing with this test.

2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 4

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. FTPS SIGNAL VALID BUT STUCK
1. With the scan tool monitor the FTPS voltage.
2. Remove the gas cap.

Did the voltage change?

Yes

- Go To 3

No

- Follow the diagnostic procedure for P1457- FUEL TANK PRESSURE SENSOR CIRCUIT HIGH P1457.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. FUEL TANK ISOLATION VALVE (FTIV) STUCK OR OPEN
1. With the scan tool, actuate the FTIV.

Did FTIV state change?

Yes

- Go To 4

No

- Follow the diagnostic procedure for P2450- FUEL TANK ISOLATION VALVE CIRCUIT OPEN. P2450.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. (F856) 5-VOLT SUPPLY CIRCUIT




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

Is the voltage between 4.5 to 5.2 Volts?

Yes

- Go To 5

No

- Go To 9

5. FTPS SENSOR
1. With a scan tool, monitor the FTPS Sensor voltage with the Sensor harness connector disconnected.

NOTE: The sensor voltage should be approximately 5.0 volts (plus or minus.1 of a 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 FTPS Sensor and Powertrain Control Module connectors. Replace the FTPS Sensor if no problems were found with the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. (N7) FTPS 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) FTPS Signal circuit in the FTPS Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

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

No

- Go To 7

7. (N7) FTPS SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT




1. Measure the resistance between the (N7) FTPS Signal circuit and the (K900) Sensor ground circuit in the FTPS Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the (K900) Sensor ground circuit and the (N7) FTPS Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

8. EXCESSIVE RESISTANCE IN THE (N7) FTPS 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 PCM Pinout Box 8815 to perform diagnosis.

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

Is the resistance below 5.0 Ohms?

Yes

- Go To 11

No

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

9. (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 PCM Pinout Box 8815 to perform diagnosis.

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

Is the resistance below 5.0 Ohms?

Yes

- Go To 10

No

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

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




1. Measure the resistance between ground and the (F856) 5-volt Supply circuit in the FTPS 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 11

11. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the FTPS 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 FTPS Sensor and Powertrain Control Module connectors.
4. Perform 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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