DTC P0181: Fuel Tank Temperature Sensor Circuit Range/Performance

CIRCUIT OPERATION

• 5-volt voltage is applied to the fuel tank temperature sensor output terminal (terminal No. 3) from the ECM (terminal No. 115) via the resistor in the ECM.
  
• The fuel tank temperature sensor output voltage increases when the resistance increases and decreases when the resistance decreases. The ground terminal (terminal No. 1) is grounded to the vehicle body.
  

TECHNICAL DESCRIPTION

• The fuel tank temperature sensor converts the fuel tank temperature to a voltage.
  
• The ECM detects the fuel tank temperature with this output voltage.
  

DESCRIPTIONS OF MONITOR METHODS

Fuel tank temperature at engine start is higher than engine coolant temperature at engine start by specified value when engine is cold start condition.

MONITOR EXECUTION

Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

• Not applicable
  

• Engine coolant temperature sensor
  
• Intake air temperature sensor
  

DTC SET CONDITIONS

• The engine coolant temperature - intake air temperature is 5°C (9°F) or less when the engine is started.
  
• The engine coolant temperature is between
  -10°C (14°F) and 36°C (97°F) when the engine is started.
  
• The engine coolant temperature is higher than 60°C (140°F).
  
• Maximum vehicle speed is higher than 30 km/h (19 mph) after the engine starting sequence has been completed.
  

• The fuel tank temperature - engine coolant temperature is 15°C (27°F) or more when the engine is started.
  

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 14 .

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

• Fuel tank temperature sensor failed.
  
• Open or shorted fuel tank temperature sensor circuit, harness damage, or connector damage.
  
• ECM failed.
  

caution To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. (1)Connect scan tool MB991958 to the data link connector. (2)Turn the ignition switch to the "ON" position. (3)Set scan tool MB991958 to the data reading mode for item 53, Fuel Tank Temperature Sensor. Approximately the same as the ambient air temperature when the engine is cooled. (4)Turn the ignition switch to the "LOCK" (OFF) position. Q. Is the sensor operating properly? It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions . Go to Step 2.

	Go to Step 3.

	Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

(2)Measure the resistance between terminal No. 1 and No. 3 of the fuel tank temperature sensor. Standard value: 0.5 - 12.0 kΩ Q. Is the measured resistance between 0.5 and 12.0 kΩ? Go to Step 4. Replace the fuel tank temperature sensor. Then go to Step 11.

(2)Check for the continuity between terminal No. 1 and ground. Continuity (2 Ω or less) Q. Does continuity exist? Go to Step 5. Repair harness wire between fuel tank temperature sensor connector D-18 (terminal No. 1) and ground because of open circuit or harness damage. Then go to Step 11.

(3)Measure the voltage between terminal No. 3 and ground. Voltage should be between 4.5 and 4.9 volts (4)Turn the ignition switch to the "LOCK" (OFF) position. Q. Is the measured voltage between 4.5 and 4.9 volts? Go to Step 9. Go to Step 6.

	Go to Step 7.

	Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

(1)Disconnect all ECM connectors. Connect the power plant ECU check harness special tool MB992110 between the separated connectors. (2)Turn the ignition switch to the "ON" position.

(3)Measure the voltage between terminal No. 115 and ground. When fuel tank temperature is 0°C (32°F), voltage should be between 2.7 and 3.1 volts. When fuel tank temperature is 20°C (68°F), voltage should be between 2.1 and 2.5 volts. When fuel tank temperature is 40°C (104°F), voltage should be between 1.6 and 2.0 volts. When fuel tank temperature is 80°C (176°F), voltage should be between 0.8 and 1.2 volts. (4)Turn the ignition switch to the "LOCK" (OFF) position. Q. Is the measured voltage normal? Check harness connector C-39 at intermediate connector for damage, and repair or replace as required. Refer to GROUP 00E, Harness Connector Inspection . If intermediate connector is in good condition, repair harness wire between fuel tank temperature sensor connector D-18 (terminal No. 3) and ECM connector B-109 (terminal No. 115) because of open circuit. Then go to Step 11. Go to Step 8.

note Check harness after checking intermediate connector C-39. If intermediate connector is damaged, repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

	Replace the ECM. When the ECM is replaced, register the ID code. Refer to GROUP 42B, Diagnosis - ID Code Registration Judgment Table <Vehicles with KOS> or GROUP 42C, Diagnosis - ID Codes Registration Judgment Table <Vehicles with WCM> . Then go to Step 11.

	Repair it. Then go to Step 11.

	Go to Step 10.

	Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

note Check harness after checking intermediate connector C-39. If intermediate connector is damaged, repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

	Replace the ECM. When the ECM is replaced, register the ID code. Refer to GROUP 42B, Diagnosis - ID Code Registration Judgment Table <Vehicles with KOS> or GROUP 42C, Diagnosis - ID Codes Registration Judgment Table <Vehicles with WCM> . Then go to Step 11.

	Repair it. Then go to Step 11.

(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 14 .

	Retry the troubleshooting.

	The inspection is complete.