P0181
P0181 FTT Sensor
Component Description
The fuel tank temperature sensor is used to detect the fuel temperature inside the fuel tank. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the fuel temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.
[Reference data]
*: This data is reference value and is measured between ECM terminal 107 (fuel tank temperature sensor) and 116 (ECM ground).
CAUTION:
Never use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
On Board Diagnosis Logic
DTC Confirmation Procedure
1. INSPECTION START
Is it necessary to erase permanent DTC?
YES
GO TO 7.
NO
GO TO 2.
2. PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next test.
1 Turn ignition switch OFF and wait at least 10 seconds.
2 Turn ignition switch ON.
3 Turn ignition switch OFF and wait at least 10 seconds.
GO TO 3.
3. PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A-I
1 Turn ignition switch ON and wait at least 10 seconds.
2 Check 1st trip DTC.
Is 1st trip DTC detected?
YES
Go to "Diagnosis Procedure".
NO
GO TO 4.
4. CHECK ENGINE COOLANT TEMPERATURE
With SDT
1 Select "COOLAN TEMP/S" in "Data list" mode with SDT.
2 Check "COOLAN TEMP/S" indication.
With GST
Follow the procedure "With SDT" above.
Is "COOLAN TEMP/S" indication less than 60 °C (140 °F)?
YES
INSPECTION END
NO
GO TO 5.
5. PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A-II
With SDT
1 Cool engine down until "COOLAN TEMP/S" indication is less than 60 °C (140 °F).
2 Wait at least 10 seconds.
3 Check 1st trip DTC.
With GST
Follow the procedure "With SDT" above.
Is 1st trip DTC detected?
YES
Go to "Diagnosis Procedure".
NO
GO TO 6.
6. PERFORM COMPONENT FUNCTION CHECK (FOR MALFUNCTION B)
Perform component function check. Refer to "Component Function Check".
NOTE:
Use the component function check to check the overall function of the FTT sensor circuit. During this check, a 1st trip DTC might not be confirmed.
Is the inspection result normal?
YES
INSPECTION END
NO
Proceed to "Diagnosis Procedure".
7. PRECONDITIONING
If DTC CONFIRMATION PROCEDURE has been previously conducted, always perform the following procedure before conducting the next test.
1 Turn ignition switch OFF and wait at least 10 seconds.
2 Turn ignition switch ON.
3 Turn ignition switch OFF and wait at least 10 seconds.
TESTING CONDITION:
- Before performing the following procedure, do not add fuel.
- Before performing the following procedure, check that fuel level is between 1/4 and 4/4.
- Before performing the following procedure, confirm that battery voltage is 11 V or more at idle.
GO TO 8.
8. PERFORM DTC CONFIRMATION PROCEDURE B
1 Start engine and let it idle for 60 minutes.
2 Move the vehicle to a cool place.
NOTE:
Cool the vehicle in an environment of ambient air temperature between -10 °C (14 °F) and 35 °C (95 °F).
3 Turn ignition switch OFF and soak the vehicle for 12 hours.
CAUTION:
Never turn ignition switch ON during soaking.
NOTE:
The vehicle must be cooled with the food open.
4 Start engine and let it idle for 5 minutes or more.
CAUTION:
Never turn ignition switch OFF during idling.
5 Check 1st trip DTC.
Is 1st trip DTC detected?
YES
Proceed to "Diagnosis Procedure".
NO
INSPECTION END
Component Function Check
1. CHECK FUEL TANK TEMPERATURE (FTT) SENSOR
1 Turn ignition switch OFF.
2 Disconnect fuel level sensor unit and fuel pump harness connector.
3 Remove fuel level sensor unit. Refer to [Fuel Level Sensor Unit, Fuel Filter and Fuel Pump Assembly: Removal and Installation] Removal and Replacement.
4 Check resistance between fuel level sensor unit and fuel pump terminals by heating with hot water as shown in the figure.
Is the inspection result normal?
YES
GO TO 2.
NO
Proceed to "Diagnosis Procedure".
2. CHECK INTERMITTENT INCIDENT
Check intermittent incident. Refer to [Service Information for Electrical Incident: Intermittent Incident] Service Information for Electrical Incident: Intermittent Incident.
Is the inspection result normal?
YES
INSPECTION END
NO
Proceed to "Diagnosis Procedure".
Diagnosis Procedure
1. INSPECTION START
Confirm the detected malfunction (A or B). Refer to "On Board Diagnosis Logic".
Which malfunction is detected?
A
GO TO 2.
B
GO TO 7.
2. CHECK COMBINATION METER FUNCTION
Refer to [Diagnosis and Repair Workflow: Meter, Warning Lamp and Indicator] Diagnosis and Repair Workflow Meter, Warning Lamp and Indicator.
OK or NG
OK
GO TO 3.
NG
Go to [Fuel Level Sensor Signal Circuit Check] Testing and Inspection.
3. CHECK FUEL TANK TEMPERATURE SENSOR POWER SUPPLY CIRCUIT
1 Turn ignition switch OFF.
2 Disconnect "fuel level sensor unit and fuel pump" harness connector.
3 Turn ignition switch ON.
4 Check voltage between "fuel level sensor unit and fuel pump" terminal 4 and ground with SDT or tester.
OK or NG
OK
GO TO 5.
NG
GO TO 4.
4. DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors E41, C1
- Harness for open or short between ECM and "fuel level sensor unit and fuel pump"
Repair harness or connector.
5. CHECK FUEL TANK TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
1 Turn ignition switch OFF.
2 Check harness continuity between "fuel level sensor unit and fuel pump" terminal 3 and ground. Refer to Wiring Diagram.
3 Also check harness for short to power.
OK or NG
OK
GO TO 7.
NG
GO TO 6.
6. DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors E41, C1
- Harness for open or short between "fuel level sensor unit and fuel pump" ground
Repair open circuit or short to power in harness or connector.
7. CHECK FUEL TANK TEMPERATURE SENSOR
Refer to "Component Inspection".
OK or NG
OK
GO TO 8.
NG
Replace fuel level sensor unit. Refer to [Fuel Level Sensor Unit, Fuel Filter and Fuel Pump Assembly: Removal and Installation] Removal and Replacement.
8. CHECK INTERMITTENT INCIDENT
Refer to [Service Information for Electrical Incident: Intermittent Incident] Service Information for Electrical Incident: Intermittent Incident.
INSPECTION END
Component Inspection
Fuel Tank Temperature Sensor
1) Remove fuel level sensor unit. Refer to [Fuel Level Sensor Unit, Fuel Filter and Fuel Pump Assembly: Removal and Installation] Removal and Replacement.
2) Check resistance between "fuel level sensor unit and fuel pump" terminals 3 and 4 by heating with hot water or heat gun as shown in the figure.
